Help with static vs apparent mass of rotating wheel [Archive]

Ben C

01-03-1970, 08:26 PM

On 2007-11-23, bicycle_disciple <1.crazyboy.only@gmail.com> wrote:
> I have a question for someone good in Physics of wheels,
>
> The apparent mass of an accelarating wheel is higher (certainly
> higher, but the magnitude is debatable) than that of a constant-speed
> wheel.
>
> How can one calculate that apparent mass?
>
>
> Is it : Apparent Mass = Static Mass + [MOI/(RADIUS^2)]
>
>
> MOI being the moment of inertia about the center of the wheel
> RADIUS = radius of a 700 C wheel in meters (measured at the center of
> the inside of the bare rim)
>
> Am I right here? That would make sense because Ratio of Apparent Mass
> to Static Mass would lie anywhere from 1.4 to 1.8. A value tending
> more towards 2.0 means that all the mass is concentrated on the rim on
> the wheel. For the high quality wheels we all ride and race on, this
> can't be really possible, and so the difference between top wheels are
> probably negligable.
>
> Please correct me here.

Not really sure what you mean by "apparent mass".

One way to approach these calculations is to consider the amount of
rotational kinetic energy and linear kinetic energy in the wheel.

If a wheel is travelling at 30kph (which is 8.33m/s), then its linear ke
is given by mv^2 / 2 (m is mass and v is linear velocity). So if its
mass is 0.4kg, then that's 13.9J of linear ke.

Its rotational ke is given by Iw^2 / 2 where I is its moment of inertia
and w is its angular velocity, which is equal to v / r.

Now you've just been doing some tests to measure MOI, but there are
formulas on Wikipedia for working out the MOI of a cylinder.

For a thin-walled cylinder, I = mr^2 [1].

With a bit of juggling of equations, you can see that the rotational ke
R is:

R = Iw^2 / 2
R = (mr^2 * w^2) / 2
R = (mr^2 * v^2) / (2 * r^2)
R = mv^2 / 2

i.e. equal to the linear ke (which is also mv^2 / 2, see above). That
means that at a given speed, the wheel stores the same amount of energy
_again_ as rotational ke as it does as linear ke.

This I think is where the value 2.0 comes from for a wheel with all the
mass around the outside, and is why people sometimes say saving weight
on your rims is worth nearly twice saving it anywhere else. Only nearly
twice because of course the weight isn't all right on the outside (but
fairly close).

You have to put all that energy in, and the rate at which you can put it
in is limited by your power, so you will get a bigger improvement in
acceleration with lighter wheels than if you saved the same amount of
actual weight on say the handlebars.

But having said that, the weight of a rim (400g) is only a very small
percentage of the weight of the whole bike and rider, and the difference
in weight between say a cheap road rim and a top of the range road rim
is an even smaller percentage. All the same, if it's between spending
those $200 to save 40g off the rims or the same $200 to save 40g off the
handlebars, then you might as well spend it on the rims.

Note also that even with heavy wheels you don't lose that energy-- it's
stored up for you and you get it back-- coasting down for longer, for
example.

In fact for two bicycles of equal overall weight, one that had more of
the weight concentrated on the rims might be the easier machine to ride
down and up hills. You'd go slower down the hills, thus dissipating less
energy to the wind. The total stored energy at the bottom of the hill
(to help carry you up the next one) would therefore be higher.

[1] If you want to take rim depth into account, then you can use the
more general formula I = 0.5 * m * (r1^2 + r2^2) where r1 and r2 are the
inside and outside radii of the cylinder-- i.e. r2 = r1 - rim depth. It
doesn't make much difference though. You will find that rotational ke is
a little bit less than linear: I make them 12.8J and 13.9J for a 400g
rim at 30kph.

But it would be interesting to see how your measurements of MOI for
wheels with your pendulum test compare to predicted MOIs based on 0.5 *
m * (r1^2 + r2^2).

M-gineering

01-03-1970, 08:26 PM

A Muzi wrote:
> bicycle_disciple wrote:
>> I have a question for someone good in Physics of wheels,
>> The apparent mass of an accelarating wheel is higher (certainly
>> higher, but the magnitude is debatable) than that of a constant-speed
>> wheel.
>> How can one calculate that apparent mass?
>>
>> Is it : Apparent Mass = Static Mass + [MOI/(RADIUS^2)]
>>
>> MOI being the moment of inertia about the center of the wheel
>> RADIUS = radius of a 700 C wheel in meters (measured at the center of
>> the inside of the bare rim)
>> Am I right here? That would make sense because Ratio of Apparent Mass
>> to Static Mass would lie anywhere from 1.4 to 1.8. A value tending
>> more towards 2.0 means that all the mass is concentrated on the rim on
>> the wheel. For the high quality wheels we all ride and race on, this
>> can't be really possible, and so the difference between top wheels are
>> probably negligable.
>> Please correct me here.
>
> A rim is about 400g, a tire 200-ish, tube 65g rim liner 12g. Feeling
> lucky on this? Add 30g of brass nipples. Compare to a bike+rider weight
> a hundred thousand grams and what does it matter??
>
> p.s. negligible

It is wrong to compare wheelweight with total bodymass. Comparing it
with 1400 grams of brain is more realistic!

--
/Marten

info(apestaartje)m-gineering(punt)nl

carlfogel@comcast.net

01-03-1970, 08:26 PM

On Fri, 23 Nov 2007 17:41:23 -0600, Ben C <spamspam@spam.eggs> wrote:

[snip]

>You have to put all that energy in, and the rate at which you can put it
>in is limited by your power, so you will get a bigger improvement in
>acceleration with lighter wheels than if you saved the same amount of
>actual weight on say the handlebars.
>
>But having said that, the weight of a rim (400g) is only a very small
>percentage of the weight of the whole bike and rider, and the difference
>in weight between say a cheap road rim and a top of the range road rim
>is an even smaller percentage. All the same, if it's between spending
>those $200 to save 40g off the rims or the same $200 to save 40g off the
>handlebars, then you might as well spend it on the rims.
>
>Note also that even with heavy wheels you don't lose that energy-- it's
>stored up for you and you get it back-- coasting down for longer, for
>example.
>
>In fact for two bicycles of equal overall weight, one that had more of
>the weight concentrated on the rims might be the easier machine to ride
>down and up hills. You'd go slower down the hills, thus dissipating less
>energy to the wind. The total stored energy at the bottom of the hill
>(to help carry you up the next one) would therefore be higher.

[snip]

Dear Ben,

In practical riding, however, the heavier wheels are likely to be
worse because bicyclists accelerate like snails, but brake like
demons.

In other words, we slowly pedal up to top speed and then throw most of
our painfully gained and stored momentum when we hit the brakes at the
first turn.

As Andrew points out, the difference in realistic wheels is
negligible, requiring considerable calculation to arrive at tiny
numbers.

You can use the Analytic Cycling wind page to calculate some wheel
effects--leave the wind alone, use identical wheels, and then reduce
the weight of one wheel set:

http://www.analyticcycling.com/DiffEqWindCourse_Page.html

I tried a pair of G36 wheels, changing the weight to match, and the
calculator predicted 466.98 seconds for both.

Take 200 grams off each wheel on one bike, and the time drops to
466.29 seconds, about 7/10ths of a second faster for the slightly
lighter bike that accelerates slightly faster on a theoretical 4 km TT
course with no theoretical braking.

In contrast, slightly heavier wheels with better aerodynamics (the
default for the right-hand bike) can take about 12 seconds off the
same time.

Time trial bikes are typically heavier because they're trying to
reduce wind drag through delicate fairing effects, not because they're
hoping to store more momentum in their deep section rims for hills.

Cheers,

Carl Fogel

Tom Ace

01-03-1970, 08:26 PM

On Nov 23, 6:41 pm, Ben C <spams...@spam.eggs> wrote:

> [ various calculations omitted ]
> i.e. equal to the linear ke (which is also mv^2 / 2, see above). That
> means that at a given speed, the wheel stores the same amount of energy
> _again_ as rotational ke as it does as linear ke.

Yes-- and even more simply demonstrated by noting that a point on the
edge
of a wheel has a tangential speed equal to the forward speed of the
vehicle.

Tom Ace

Ben C

01-03-1970, 08:27 PM

On 2007-11-24, carlfogel@comcast.net <carlfogel@comcast.net> wrote:
> On Fri, 23 Nov 2007 17:41:23 -0600, Ben C <spamspam@spam.eggs> wrote:
[...]
>>In fact for two bicycles of equal overall weight, one that had more of
>>the weight concentrated on the rims might be the easier machine to ride
>>down and up hills. You'd go slower down the hills, thus dissipating less
>>energy to the wind. The total stored energy at the bottom of the hill
>>(to help carry you up the next one) would therefore be higher.
>
[...]
> Time trial bikes are typically heavier because they're trying to
> reduce wind drag through delicate fairing effects, not because they're
> hoping to store more momentum in their deep section rims for hills.

Yes of course. I'm not really making the case for flywheels here. Some
way to store energy down hills (or some kind of regenerative braking)
would be useful. But the problem is how to achieve that without adding
much weight.

I was comparing two bicycles _of the same overall weight_ one of which
had more of the weight on the rims. In other words the bike with the
heavier rims had a lighter frame to make up for it. I suspect that in
almost all conditions you'd still be better off with the lighter wheels
on the lighter frame because it's less overall weight to carry up the
hills.

I'm also working on the assumption that you don't care too much how
slowly you go down the hill. The idea is you coast down the hill without
braking or pedalling. The heavy wheeled bike is going slower at the
bottom but is slightly easier to ride up the other side. This is because
it lost less energy on the way down to wind resistance since it was
moving more slowly. This might be good if you're riding to the shops
but is no use to a time trial rider who wants to go fast down hills as
well as up them.

SocSecTrainWreck@earthlink.net

01-03-1970, 08:27 PM

carlfo...@comcast.net wrote:
> Take 200 grams off each wheel on one bike, and the time drops to
> 466.29 seconds, about 7/10ths of a second faster for the slightly
> lighter bike that accelerates slightly faster on a theoretical 4 km TT
> course with no theoretical braking.
>
> In contrast, slightly heavier wheels with better aerodynamics (the
> default for the right-hand bike) can take about 12 seconds off the
> same time.

Sometime it might be worth it to consider the effect of rotating mass
on a massed start race or a sprint, instead of using the unrealistic
example of a 4km tt with no braking, which could only happen in a
velodrome. Even the .7 seconds there (which can be quite significant
on the track) becomes much larger on a 50 km individual road tt,
before even accounting for the effects of braking. This is not to say
that weight is more important than aerodynamics in a road tt, but the
difference is more important than breakfast and should not be
discounted. (Breakfast is usually a constant, BTW. Even for me as a
non-racing cyclist I am pretty consistent about what I eat before any
ride of more than about 20 miles.You can screw up your ride or race by
eating poorly, but you are not likely to gain 10 seconds by having an
especially perfect breakfast before a 50 mile ride. ) Obviously, in
massed start racing, particularly for criteriums where acceleration is
constant, and for sprinting, rotating mass is even more important. The
tradeoff between rotating mass and aerodynamics is complex, not
something where you can automatically dismiss one of the two variables
as insignificant. As I have commented repeatedly, the problem with
this ng seems to be everyone's desire to express their opinions in
absolutes instead of considering the complexity of an issue.

Always use the lightest, most aerodynamic, most reliable wheels you
can afford.

carlfogel@comcast.net

01-03-1970, 08:33 PM

On Sun, 25 Nov 2007 08:17:45 -0800 (PST),
SocSecTrainWreck@earthlink.net wrote:

>
>
>carlfo...@comcast.net wrote:
>> Take 200 grams off each wheel on one bike, and the time drops to
>> 466.29 seconds, about 7/10ths of a second faster for the slightly
>> lighter bike that accelerates slightly faster on a theoretical 4 km TT
>> course with no theoretical braking.
>>
>> In contrast, slightly heavier wheels with better aerodynamics (the
>> default for the right-hand bike) can take about 12 seconds off the
>> same time.
>
>Sometime it might be worth it to consider the effect of rotating mass
>on a massed start race or a sprint, instead of using the unrealistic
>example of a 4km tt with no braking, which could only happen in a
>velodrome. Even the .7 seconds there (which can be quite significant
>on the track) becomes much larger on a 50 km individual road tt,
>before even accounting for the effects of braking. This is not to say
>that weight is more important than aerodynamics in a road tt, but the
>difference is more important than breakfast and should not be
>discounted. (Breakfast is usually a constant, BTW. Even for me as a
>non-racing cyclist I am pretty consistent about what I eat before any
>ride of more than about 20 miles.You can screw up your ride or race by
>eating poorly, but you are not likely to gain 10 seconds by having an
>especially perfect breakfast before a 50 mile ride. ) Obviously, in
>massed start racing, particularly for criteriums where acceleration is
>constant, and for sprinting, rotating mass is even more important. The
>tradeoff between rotating mass and aerodynamics is complex, not
>something where you can automatically dismiss one of the two variables
>as insignificant. As I have commented repeatedly, the problem with
>this ng seems to be everyone's desire to express their opinions in
>absolutes instead of considering the complexity of an issue.
>
>Always use the lightest, most aerodynamic, most reliable wheels you
>can afford.

Dear SSTW,

Okay, I'll consider the complexities.

You mention a ten-second advantage in a 50 mile ride.

At 25 mph, a 50-mile ride takes about two hours.

10 seconds / 7200 seconds = 0.14% change

Please weigh your breakfasts, especially perfect or otherwise, for the
next week and let us know how much they vary.

A scale like this will be necessary for accuracy:

http://groups.google.com/group/rec.bicycles.tech/msg/452a28c1aa384c7d

:-)

Alternatively, you could time the same 50-mile ride for the next 7
days and let us know the variation in performance, especially perfect
or otherwise.

More practically, we could use this calculator for easy comparisons:

http://austinimage.com/bp/velocity/velocity.html

Using the defaults and a 50 mile distance, we want to reduce the
131.78 minutes ten seconds, or ~0.17 minutes, to 131.61.

Raising the temperature from 70F to 72F drops the time to ~131.61.

A tailwind blowing 0.045 mph also does the trick.

Raising power from 300 to 301 watts works, too.

Cheers,

Carl Fogel

frkrygow@gmail.com

01-03-1970, 08:33 PM

On Nov 25, 11:17 am, SocSecTrainWr...@earthlink.net wrote:
>
> As I have commented repeatedly, the problem with
> this ng seems to be everyone's desire to express their opinions in
> absolutes instead of considering the complexity of an issue.
>
> Always use the lightest, most aerodynamic, most reliable wheels you
> can afford.

"Always"? Sounds like someone just expressed their opinion as an
absolute! ;-)

I think you're overstating the case for low inertia (i.e. light) rims,
especially for road riding.

First, I admit I've done only a few time trials. But the ones I've
done involved very little braking. The one I did most often had three
corners in ten miles. And of course, I took those as fast as I could,
minimizing braking. I wasn't worried about inertia losses from my
wheels - the inertia losses from my slightly overweight body made
those negligible.

What about a road race? The tiny percentage lost to differences in
wheel inertia is again probably negligible. What effect would it
have? That someone gets the jump on you and you have to draft him,
saving maybe 30% of your energy? No problem!

The only time it really matters is in a final sprint, and then the
difference between two slightly different wheels is once again
undetectable.

And for touring, day rides, commuting, or any non-competitive riding,
it matters even less.

If the tradeoff is between slightly better aerodynamics vs slightly
less inertia, other things being equal, I'd go with better aero. Aero
pays off constantly. Less inertia barely pays off at all.

- Frank Krygowski

Ben C

01-03-1970, 08:33 PM

On 2007-11-25, Tom Ace <tom239@gmail.com> wrote:
> On Nov 23, 6:41 pm, Ben C <spams...@spam.eggs> wrote:
>
>> [ various calculations omitted ]
>> i.e. equal to the linear ke (which is also mv^2 / 2, see above). That
>> means that at a given speed, the wheel stores the same amount of energy
>> _again_ as rotational ke as it does as linear ke.
>
> Yes-- and even more simply demonstrated by noting that a point on the
> edge
> of a wheel has a tangential speed equal to the forward speed of the
> vehicle.

Good point, that's a nice simple way of looking at it.

SocSecTrainWreck@earthlink.net

01-03-1970, 08:33 PM

On Nov 25, 1:38 pm, carlfo...@comcast.net wrote:
> On Sun, 25 Nov 2007 08:17:45 -0800 (PST),
>
> SocSecTrainWr...@earthlink.net wrote:
> >Sometime it might be worth it to consider the effect of rotating mass
> >on a massed start race or a sprint, instead of using the unrealistic
> >example of a 4km tt with no braking, which could only happen in a
> >velodrome. Even the .7 seconds there (which can be quite significant
> >on the track) becomes much larger on a 50 km individual road tt,
> >before even accounting for the effects of braking. This is not to say
> >that weight is more important than aerodynamics in a road tt, but the
> >difference is more important than breakfast and should not be
> >discounted. (Breakfast is usually a constant, BTW. Even for me as a
> >non-racing cyclist I am pretty consistent about what I eat before any
> >ride of more than about 20 miles.You can screw up your ride or race by
> >eating poorly, but you are not likely to gain 10 seconds by having an
> >especially perfect breakfast before a 50 mile ride. ) Obviously, in
> >massed start racing, particularly for criteriums where acceleration is
> >constant, and for sprinting, rotating mass is even more important. The
> >tradeoff between rotating mass and aerodynamics is complex, not
> >something where you can automatically dismiss one of the two variables
> >as insignificant. As I have commented repeatedly, the problem with
> >this ng seems to be everyone's desire to express their opinions in
> >absolutes instead of considering the complexity of an issue.
>
> >Always use the lightest, most aerodynamic, most reliable wheels you
> >can afford.
>
> Dear SSTW,
>
> Okay, I'll consider the complexities.
>
> You mention a ten-second advantage in a 50 mile ride.
>
> At 25 mph, a 50-mile ride takes about two hours.
>
> 10 seconds / 7200 seconds = 0.14% change
>
> Please weigh your breakfasts, especially perfect or otherwise, for the
> next week and let us know how much they vary.

I don't need to weigh them because the difference of a few tiny grams
will not make any difference; my homemade sports drinks are already
precisely measured. The reality is that the weight of my wheels is
going to have more effect on how my breakfast is metabolized than +- a
few grams of carbs.

> Alternatively, you could time the same 50-mile ride for the next 7
> days and let us know the variation in performance, especially perfect
> or otherwise.

But this is completely beside the point; what's at issue is not the
variance among rides, it is the variance in the same ride, and the
lighter wheel always beats the heavier wheel on the same ride with all
other things being equal. And what this means is a 10+ second
advantage over 50km to the TTer with those lighter wheels. Of course,
in a massed start race the advantage of lighter wheels is much greater
unless you are planning to solo off the front (or back) for a
significant amount of time.

> Using the defaults and a 50 mile distance, we want to reduce the
> 131.78 minutes ten seconds, or ~0.17 minutes, to 131.61.
>
> Raising the temperature from 70F to 72F drops the time to ~131.61.
>
> A tailwind blowing 0.045 mph also does the trick.
>
> Raising power from 300 to 301 watts works, too.

I'll take the tailwind (which would be quite a piece of luck if the
course were a circle), raise my output by 1 watt, maybe take the
higher temperature, AND- I'll take the lighter wheels.

joseph.santaniello@gmail.com

01-03-1970, 08:34 PM

On Nov 26, 1:18 am, SocSecTrainWr...@earthlink.net wrote:
> On Nov 25, 1:38 pm, carlfo...@comcast.net wrote:
>
>
>
> > On Sun, 25 Nov 2007 08:17:45 -0800 (PST),
>
> > SocSecTrainWr...@earthlink.net wrote:
> > >Sometime it might be worth it to consider the effect of rotating mass
> > >on a massed start race or a sprint, instead of using the unrealistic
> > >example of a 4km tt with no braking, which could only happen in a
> > >velodrome. Even the .7 seconds there (which can be quite significant
> > >on the track) becomes much larger on a 50 km individual road tt,
> > >before even accounting for the effects of braking. This is not to say
> > >that weight is more important than aerodynamics in a road tt, but the
> > >difference is more important than breakfast and should not be
> > >discounted. (Breakfast is usually a constant, BTW. Even for me as a
> > >non-racing cyclist I am pretty consistent about what I eat before any
> > >ride of more than about 20 miles.You can screw up your ride or race by
> > >eating poorly, but you are not likely to gain 10 seconds by having an
> > >especially perfect breakfast before a 50 mile ride. ) Obviously, in
> > >massed start racing, particularly for criteriums where acceleration is
> > >constant, and for sprinting, rotating mass is even more important. The
> > >tradeoff between rotating mass and aerodynamics is complex, not
> > >something where you can automatically dismiss one of the two variables
> > >as insignificant. As I have commented repeatedly, the problem with
> > >this ng seems to be everyone's desire to express their opinions in
> > >absolutes instead of considering the complexity of an issue.
>
> > >Always use the lightest, most aerodynamic, most reliable wheels you
> > >can afford.
>
> > Dear SSTW,
>
> > Okay, I'll consider the complexities.
>
> > You mention a ten-second advantage in a 50 mile ride.
>
> > At 25 mph, a 50-mile ride takes about two hours.
>
> > 10 seconds / 7200 seconds = 0.14% change
>
> > Please weigh your breakfasts, especially perfect or otherwise, for the
> > next week and let us know how much they vary.
>
> I don't need to weigh them because the difference of a few tiny grams
> will not make any difference; my homemade sports drinks are already
> precisely measured. The reality is that the weight of my wheels is
> going to have more effect on how my breakfast is metabolized than +- a
> few grams of carbs.
>
> > Alternatively, you could time the same 50-mile ride for the next 7
> > days and let us know the variation in performance, especially perfect
> > or otherwise.
>
> But this is completely beside the point; what's at issue is not the
> variance among rides, it is the variance in the same ride, and the
> lighter wheel always beats the heavier wheel on the same ride with all
> other things being equal. And what this means is a 10+ second
> advantage over 50km to the TTer with those lighter wheels. Of course,
> in a massed start race the advantage of lighter wheels is much greater
> unless you are planning to solo off the front (or back) for a
> significant amount of time.
>
> > Using the defaults and a 50 mile distance, we want to reduce the
> > 131.78 minutes ten seconds, or ~0.17 minutes, to 131.61.
>
> > Raising the temperature from 70F to 72F drops the time to ~131.61.
>
> > A tailwind blowing 0.045 mph also does the trick.
>
> > Raising power from 300 to 301 watts works, too.
>
> I'll take the tailwind (which would be quite a piece of luck if the
> course were a circle), raise my output by 1 watt, maybe take the
> higher temperature, AND- I'll take the lighter wheels.

My last 3 outings at our club 10km TT have all had finish times within
a 2 second range. Where do I place an order for this additional 1W?

Joseph

dustoyevsky@mac.com

01-03-1970, 08:35 PM

On Nov 25, 10:11 pm, frkry...@gmail.com wrote:

> I think you're overstating the case for low inertia (i.e. light) rims,
> especially for road riding.

Giving an estimated by calculation difference is not overstating a
case.

Moreover, given the negative (to use the word in a narrow sense here,
please) mindset of folks who offer up these calculations, the preface
to any estimate of time gains might well be "at least".

Seven seconds in a 40k TT is kinda huge. Like having another States
medal in the palmares (ahem), or even just knowing you have some
advantage, which is not a trifle for a fifty-mile road race or hundred-
mile Sunday ride, over someone else not running "light" (or aero).

> First, I admit I've done only a few time trials.

Racing is not a life assignment.

> But the ones I've
> done involved very little braking. The one I did most often had three
> corners in ten miles. And of course, I took those as fast as I could,
> minimizing braking. I wasn't worried about inertia losses from my
> wheels - the inertia losses from my slightly overweight body made
> those negligible.

Seven seconds for the example given is not negligible. A tenth, given
the vagaries of timing at amateur events, might be in that class. Any
gain in accelerating less mass is gravy. Your training and breakfast
choice are apart.

> What about a road race? The tiny percentage lost to differences in
> wheel inertia is again probably negligible. What effect would it
> have? That someone gets the jump on you and you have to draft him,
> saving maybe 30% of your energy? No problem!

Seven seconds at the end of a short 40k mass start race, plus whatever
is gained, no matter how small, for every jump. In a crit, jumping out
of every corner (esp. in the V's <g>), "that would be more".

If "someone gets the jump on you", you have to cover the move. At some
point, an attack might (or will) succeed. That's what goes on, perhaps
most notably, at the end of many pro events, whether going uphill at a
mountaintop GT finish, or on the "flat" cobbles of Paris-Roubaix. You
can watch the films of the pros or go to the local parking lot crit,
the same thing goes on-- attacking to gain an advantage, then pressing
the advantage home for the W.

>The only time it really matters is in a final sprint, and then the
>difference between two slightly different wheels is once again
>undetectable.

As above, there might ("will be") be many "sprints" in an event, often
starting right from the gun, even in a road race at the amateur level.
And you want to be as fresh as possible for that all-out final lunge
to the line. Perhaps the most important goal of race tactics, there.

>And for touring, day rides, commuting, or any non-competitive riding,
>it matters even less.

Touring, you don't do on light equipment. At least I didn't, although
I did see one or two with tubular tire woes who tried it in the 70's.
(Finding a sewup tire in a small town bikeshop was even more difficult
than finding one of those newfangled 700c clinchers back then).

Commuting? You wanna be late for work with that "I had a flat" excuse
again?

Non-competitive probably exists <g> but every group ride I've ever
been on involved some sort of competition at some level. Weight
consciousness is prevalent, both bike and body (not to mention
comparing bling factor).

> If the tradeoff is between slightly better aerodynamics vs slightly
> less inertia, other things being equal, I'd go with better aero. Aero
> pays off constantly.

But aero becomes effective at higher (bicyclingly speaking) speeds. If
you're not concerned with "competition", why worry in the first place?
Again, lighter = faster; but there's a point at which aero gains
overtake lightness gains. Where is that? Not under 15mph or so, while
weight is always there.

> Less inertia barely pays off at all.

Seven free seconds in 40k can be huge by whatever pay scale applies.

There's a problem in many of the "arguments" here, because the case
against high-dollar stuff (which is maybe the real discussion),
especially light or aero (or most expensive/worst of all light *and*
aero!) wheels, is not well served by saying "(at least <g>) seven
seconds at the end of a 40k ITT is neglible", when even non-racers can
plainly see this to be false. "One million one, one million two..."

FWIW, I've enjoyed telling my friend who is on his third Neuvation
rear hub (lucky he didn't get hurt IMHO after the flanges broke on the
first two), that my Muzi/Chisholm pattern rear wheel (Aerohead OC,
36h, Campy hub, 3x, db DT spokes, brass nipples, handbuilt) is trick
because it *didn't* break. But, the Neuvations were cheap, the
warranty service was great, he's got two spare front wheels now, and
his wheels are faster!

I guess we're both happy? --D-y

>
> The only time it really matters is in a final sprint, and then the
> difference between two slightly different wheels is once again
> undetectable.
>
> And for touring, day rides, commuting, or any non-competitive riding,
> it matters even less.
>
> If the tradeoff is between slightly better aerodynamics vs slightly
> less inertia, other things being equal, I'd go with better aero. Aero
> pays off constantly. Less inertia barely pays off at all.
>
> - Frank Krygowski

carlfogel@comcast.net

01-03-1970, 08:36 PM

On Mon, 26 Nov 2007 00:57:09 -0800 (PST),
"joseph.santaniello@gmail.com" <joseph.santaniello@gmail.com> wrote:

>On Nov 26, 1:18 am, SocSecTrainWr...@earthlink.net wrote:
>> On Nov 25, 1:38 pm, carlfo...@comcast.net wrote:
>>
>>
>>
>> > On Sun, 25 Nov 2007 08:17:45 -0800 (PST),
>>
>> > SocSecTrainWr...@earthlink.net wrote:
>> > >Sometime it might be worth it to consider the effect of rotating mass
>> > >on a massed start race or a sprint, instead of using the unrealistic
>> > >example of a 4km tt with no braking, which could only happen in a
>> > >velodrome. Even the .7 seconds there (which can be quite significant
>> > >on the track) becomes much larger on a 50 km individual road tt,
>> > >before even accounting for the effects of braking. This is not to say
>> > >that weight is more important than aerodynamics in a road tt, but the
>> > >difference is more important than breakfast and should not be
>> > >discounted. (Breakfast is usually a constant, BTW. Even for me as a
>> > >non-racing cyclist I am pretty consistent about what I eat before any
>> > >ride of more than about 20 miles.You can screw up your ride or race by
>> > >eating poorly, but you are not likely to gain 10 seconds by having an
>> > >especially perfect breakfast before a 50 mile ride. ) Obviously, in
>> > >massed start racing, particularly for criteriums where acceleration is
>> > >constant, and for sprinting, rotating mass is even more important. The
>> > >tradeoff between rotating mass and aerodynamics is complex, not
>> > >something where you can automatically dismiss one of the two variables
>> > >as insignificant. As I have commented repeatedly, the problem with
>> > >this ng seems to be everyone's desire to express their opinions in
>> > >absolutes instead of considering the complexity of an issue.
>>
>> > >Always use the lightest, most aerodynamic, most reliable wheels you
>> > >can afford.
>>
>> > Dear SSTW,
>>
>> > Okay, I'll consider the complexities.
>>
>> > You mention a ten-second advantage in a 50 mile ride.
>>
>> > At 25 mph, a 50-mile ride takes about two hours.
>>
>> > 10 seconds / 7200 seconds = 0.14% change
>>
>> > Please weigh your breakfasts, especially perfect or otherwise, for the
>> > next week and let us know how much they vary.
>>
>> I don't need to weigh them because the difference of a few tiny grams
>> will not make any difference; my homemade sports drinks are already
>> precisely measured. The reality is that the weight of my wheels is
>> going to have more effect on how my breakfast is metabolized than +- a
>> few grams of carbs.
>>
>> > Alternatively, you could time the same 50-mile ride for the next 7
>> > days and let us know the variation in performance, especially perfect
>> > or otherwise.
>>
>> But this is completely beside the point; what's at issue is not the
>> variance among rides, it is the variance in the same ride, and the
>> lighter wheel always beats the heavier wheel on the same ride with all
>> other things being equal. And what this means is a 10+ second
>> advantage over 50km to the TTer with those lighter wheels. Of course,
>> in a massed start race the advantage of lighter wheels is much greater
>> unless you are planning to solo off the front (or back) for a
>> significant amount of time.
>>
>> > Using the defaults and a 50 mile distance, we want to reduce the
>> > 131.78 minutes ten seconds, or ~0.17 minutes, to 131.61.
>>
>> > Raising the temperature from 70F to 72F drops the time to ~131.61.
>>
>> > A tailwind blowing 0.045 mph also does the trick.
>>
>> > Raising power from 300 to 301 watts works, too.
>>
>> I'll take the tailwind (which would be quite a piece of luck if the
>> course were a circle), raise my output by 1 watt, maybe take the
>> higher temperature, AND- I'll take the lighter wheels.
>
>My last 3 outings at our club 10km TT have all had finish times within
>a 2 second range. Where do I place an order for this additional 1W?
>
>Joseph

Dear Joseph,

You can get it either from your parents or else from harder practice.

Just a wild guess, but does the same guy usually somehow win your club
events by that same small margin?

Kinda like the Tour de France from 1999 to 2005?

Here's the victory margin for 80 to 90 hours of bicycle racing, with
total time expressed as percentages:

1st 2nd
place place
1999 100.00% 100.1387%
2000 100.00% 100.1086%
2001 100.00% 100.1301%
2002 100.00% 100.1479%
2003 100.00% 100.0202%
2004 100.00% 100.1259%
2005 100.00% 100.0942%

Armstrong never won by more than 0.15%. But I doubt that his string of
victories was due to his choice of wheels.

The belief that a tiny mechanical edge will turn also-rans into
winners is what keeps the more absurd, exotic, and expensive bicycle
accessory market thriving.

I sympathize.

Over thirty years ago, I shared similar beliefs in the power of
equipment modifications with a lot of enthusiastic Colorado trials
riders.

We all thought that if we spent hours squaring the edges of slightly
worn trials tires with razor blades to improve traction, we'd have a
chance to beat the guy who used to be champion of California.

But we never beat him.

He didn't seem to rely on tricks like that to keep his feet off the
ground. In fact, he began developing a silly little 125cc Honda trials
bike and started stomping us with that inadequate equipment.

The guy who did finally beat him took a year off from work and
practiced like a demon. And he didn't ride a good machine like a
Bultaco, Ossa, or Montesa. Instead, he rode to the state championship
on a Kawasaki, which had no known advantages, other than being cheap.

It was almost as if the rider mattered more than the equipment.

There are indeed advantages to be found in sacrificing light weight
for aerodynamics (and vice-versa) in bicycles, but the guy ahead of us
probably isn't getting there by that route.

Cheers,

Carl Fogel

frkrygow@gmail.com

01-03-1970, 08:37 PM

On Nov 26, 9:41 am, "dustoyev...@mac.com" <dustoyev...@mac.com> wrote:
> On Nov 25, 10:11 pm, frkry...@gmail.com wrote:
>
>
> > If the tradeoff is between slightly better aerodynamics vs slightly
> > less inertia, other things being equal, I'd go with better aero. Aero
> > pays off constantly.
>
> But aero becomes effective at higher (bicyclingly speaking) speeds. If
> you're not concerned with "competition", why worry in the first place?
> Again, lighter = faster; but there's a point at which aero gains
> overtake lightness gains. Where is that? Not under 15mph or so, while
> weight is always there.
>
> > Less inertia barely pays off at all.
>
> Seven free seconds in 40k can be huge by whatever pay scale applies.

You'd better decide whether you're talking about racing or not. If
you're not, neither a small reduction in wheel inertia nor a small
reduction in wheel aero drag matter, so the tradeoff between the two
is moot.

If you are talking about racing, you'd _better_ be riding over "15mph
or so." And then, that tradeoff goes in favor of aero, not less
inertia.

We also need to review the concept of "negligible." Do you shave off
your arm hair before a road race? I never did, even though I know it
would have "helped" at some level. Some effects really do disappear
in the noise.

- Frank Krygowski

Ron Ruff

01-03-1970, 08:37 PM

On Nov 26, 7:41 am, "dustoyev...@mac.com" <dustoyev...@mac.com> wrote:
> In a crit, jumping out
> of every corner (esp. in the V's <g>), "that would be more".

I'm amazed at how often I see this. If you are in a crit and "jumping
out of corners" then you are not in the race... and have much more
important issues to address than getting lighter wheels. If you are
near the front, you don't slow down for corners at all. If you need to
*get* to the front then better aerodynamics is what you need since you
will have your nose in the wind. If someone attacks then you need to
accelerate to get on their wheel, but in nearly all circumstances
better aerodynamics will help you there more than lower inertia.

dustoyevsky@mac.com

01-03-1970, 08:38 PM

On Nov 26, 11:45 am, frkry...@gmail.com wrote:

> You'd better decide whether you're talking about racing or not.

YOU'RE the one who brought racing into the discussion.

(In reaction to the typical snotty Frank Krygowski-style "you'd
better blah blah blah).

We're not in class, and I'm not one of your (poor) students, bub.

> If
> you're

HOW ABOUT *WE*!?!?!?

(there, are you awake and paying attention yet??)

> not, neither a small reduction in wheel inertia nor a small
> reduction in wheel aero drag matter, so the tradeoff between the two
> is moot.

Moot? You seem to want to think so. Other people might not, for
obvious reasons.

> If you are talking about racing, you'd _better_ be riding over "15mph
> or so." And then, that tradeoff goes in favor of aero, not less
> inertia.

Unless we're going up a long, steep climb. That's why people who can
spend a comparatively large sum on the lightest wheel they can get
with the most aero in it.

> We also need to review the concept of "negligible."

You need to "review" and be more careful about what you type, too.

> Do you shave off
> your arm hair before a road race? I never did, even though I know it
> would have "helped" at some level. Some effects really do disappear
> in the noise.

Typical Krygowsky rhetoric. Attempt to ridicule, set up a straw man.

You still didn't make that seven seconds for 40k go away, Frank.

Here's the problem (opinion). People ask a question ("What/how much is
gained from x grams weight loss"), and get an answer. You can't show
such a large gain for simple weight reduction and then say it doesn't
matter out of the other side of your mouth.

There's something else going on here. Maybe the discussion needs to be
a little more detailed? There's a problem with expensive bike gear?
And lycra jersies with writing all over them?

One figure, a very rough and word-of-mouth estimate went around during
the 80's, when disc and deep section wheels and aero bars and
"enclosed" cables came into use: difference for a 40k ITT? Two and a
half minutes.

That's why you see all those "civilians" (riders not licensed for
racing) out there with the fancy wheels and the aero bars. It's not
all ad hype by any means. --D-y

frkrygow@gmail.com

01-03-1970, 08:39 PM

On Nov 26, 2:47 pm, carlfo...@comcast.net wrote:
> On Mon, 26 Nov 2007 00:57:09 -0800 (PST),
>
>
>
> "joseph.santanie...@gmail.com" <joseph.santanie...@gmail.com> wrote:
> > Where do I place an order for this additional 1W?
>
> Dear Joseph,
>
> You can get it either from your parents or else from harder practice.

Hmm. I think it's too late to get even one more watt from my
parents! What they gave me seems to be what I'm stuck with.

> It was almost as if the rider mattered more than the equipment.

Whoa! Don't let that out, or a whole industry is going to tank. Not
to mention several dozen topics of r.b.tech conversation!

- Frank Krygowski

M-gineering

01-03-1970, 08:39 PM

carlfogel@comcast.net wrote:

>
> Just a wild guess, but does the same guy usually somehow win your club
> events by that same small margin?
>
> Kinda like the Tour de France from 1999 to 2005?
>
> Here's the victory margin for 80 to 90 hours of bicycle racing, with
> total time expressed as percentages:
>
> 1st 2nd
> place place
> 1999 100.00% 100.1387%
> 2000 100.00% 100.1086%
> 2001 100.00% 100.1301%
> 2002 100.00% 100.1479%
> 2003 100.00% 100.0202%
> 2004 100.00% 100.1259%
> 2005 100.00% 100.0942%
>

total times of a massed start race are meaningless, except as a way to
win races. The last guy in the pack gets the same finishing time as the
winner (provided the gaps are small enough), there are penalties,
bonifications, teammates, tactics......

/Marten

info(apestaartje)m-gineering(punt)nl

carlfogel@comcast.net

01-03-1970, 08:39 PM

On Mon, 26 Nov 2007 14:03:27 -0800 (PST), frkrygow@gmail.com wrote:

>On Nov 26, 2:47 pm, carlfo...@comcast.net wrote:
>> On Mon, 26 Nov 2007 00:57:09 -0800 (PST),
>>
>>
>>
>> "joseph.santanie...@gmail.com" <joseph.santanie...@gmail.com> wrote:
>> > Where do I place an order for this additional 1W?
>>
>> Dear Joseph,
>>
>> You can get it either from your parents or else from harder practice.
>
>Hmm. I think it's too late to get even one more watt from my
>parents! What they gave me seems to be what I'm stuck with.
>
>> It was almost as if the rider mattered more than the equipment.
>
>Whoa! Don't let that out, or a whole industry is going to tank. Not
>to mention several dozen topics of r.b.tech conversation!
>
>- Frank Krygowski

Dear Frank,

I suspect that embracing reincarnation or using a time machine to
rearrange my family tree would be easier than the kind of hard
practice that a lot of impressive performers use instead of equipment:

"My training as a contortionist was, of course, the first step toward
my present occupation of escaping from strait-jackets and chains, for
it is chiefly through my ability to twist my body and dislocate my
joints, together with abnormal expansion and contraction powers, which
renders me independent of the tightest bonds. Thus, to any young man
who has in mind a career similar to mine, I would say: 'First try
bending over backward and picking up a pin with your teeth from the
floor.' . . . That was _my_ first stunt."

--Harry Houdini

http://books.google.com/books?id=mIV7qFYpRNcC&pg=PA11&lpg=PA11&dq=houdini+pin+floor+teeth&source=web&ots=3LK3lSyySF&sig=0xOr1cIg8SuZjuqba-iMxsMTH0E

***

John Scarne, aged 19, explained his card-sharping trick to a group of
puzzled professional gamblers that included Arnold Rothstein:

I later learned the real reason that Rothstein and his friends went to
all the trouble they did. Two men in the group were professional card
sharks and they had told Rothstein if they saw me do the trick several
times they could detect my method and do it themselves. They felt that
I might reject any proposition they offered for an explanation, and
this was their method of finding out how the trick was accomplished.
It was also a matter of professional pride with these men who were
supposed to know all the angles of gambling, crooked or otherwise. For
these gamblers to admit that a young kid from New Jersey was fooling
the daylights out of them was just too much. However, being fooled six
nights in a row and paying twelve hundred bucks for the privilege was
the final blow to their pride.

Finally, on the sixth night Rothstein said, "O.K., Professor, give.
How do you do it?"

George McManus then interrupted, saying, "When Rothstein told us about
this we thought at first you were using slick aces [an ace treated
with a wax that permits the waxed card to be cut easily]. Then, when
we gave you our own deck and you did it again we thought you were
using a fine crimp [a card bent during a shuffle]. But, we have to
admit, kid, we don't know what it's all about."

"Well," I said, "I always give the deck one or more riffle shuffles
and hold the cards in such a manner that I can glimpse the indices on
the cards as they fly past during the shuffle. When I sight an ace I
count by feel the number of cards which fall on top of it. Then I
calculate the number of cards a player cuts, and I cut down to this
total and there is the ace." (At that early stage of my career I could
cut any number of cards called for in the deck; otherwise I would
never have given these racket men such an answer.)

With that reply McManus put the deck of cards on the table and said,
"O.K., now cut me twenty-five cards." I realized he was testing the
veracity of my statement. I squared off the deck and made a cut which
I then handed to McManus. He counted the cards aloud and reached
exactly twenty-five.

They had me repeat this feat about twenty times and I finally said to
Rothstein, "If you do the same thing for three or four hours a day
you'll be able to do it too, in about twenty years." I wasn't trying
to be smart but they had asked me a question and I was trying to give
them an answer as best I could.

"And how old are you?" someone asked rather skeptically.

"I'm nineteen," I replied matter-of-factly.

His rejoinder was quick in coming as he said, "You're nineteen and you
practiced twenty years!"

"No," I replied. "But I practice ten hours a day."

http://scarne.freeservers.com/sharks.html

***

I heard somewhere that Armstrong tended to train a little harder and a
little more carefully than Ulrich did, rather than relying just on
buying better equipment at Nashbar's spring sale and paying to ship it
to France.

Cheers,

Carl Fogel

carlfogel@comcast.net

01-03-1970, 08:39 PM

On Mon, 26 Nov 2007 23:12:59 +0100, M-gineering
<ikmotgeenspam@m-gineering.nl> wrote:

>carlfogel@comcast.net wrote:
>
>>
>> Just a wild guess, but does the same guy usually somehow win your club
>> events by that same small margin?
>>
>> Kinda like the Tour de France from 1999 to 2005?
>>
>> Here's the victory margin for 80 to 90 hours of bicycle racing, with
>> total time expressed as percentages:
>>
>> 1st 2nd
>> place place
>> 1999 100.00% 100.1387%
>> 2000 100.00% 100.1086%
>> 2001 100.00% 100.1301%
>> 2002 100.00% 100.1479%
>> 2003 100.00% 100.0202%
>> 2004 100.00% 100.1259%
>> 2005 100.00% 100.0942%
>>
>
>
>total times of a massed start race are meaningless, except as a way to
>win races. The last guy in the pack gets the same finishing time as the
>winner (provided the gaps are small enough), there are penalties,
>bonifications, teammates, tactics......
>
>
>/Marten
>
>info(apestaartje)m-gineering(punt)nl

Dear Marten,

Er, "meaningless, except as a way to win races" probably needs some
explanation.

In any case, it's funny how the same guy kept staying 0.02% or so
ahead of whoever ended up in second place after three weeks.

It's almost as if none of the other guys could quite get ahead of him
overall under the same rules in the same race, year after year, no
matter how many kinds of wheels, tires, frames, helmets, gear
clusters, brake pads, seats, spokes, tactics, drugs, and so forth that
they tried.

Armstrong certainly had good bikes, but I don't think that anyone
claimed that his rivals lost because they rode inferior bikes.

The trouble with most of the extreme equipment claims is that they
ignore the inevitable trade-offs. We'd all like to have ultra-light,
ultra-aero wheels, but at any reasonable level the rider ends up
choosing between weight and wind drag.

Carve weight off a wheel, and the wind drag goes up.

Reduce the wheel's wind drag, and the weight rises.

As Frank points out, the aero advantage tends to be much larger and
more practical than the weight advantage.

Cheers,

Carl Fogel

joseph.santaniello@gmail.com

01-03-1970, 08:39 PM

On Nov 27, 12:58 am, carlfo...@comcast.net wrote:

> Carve weight off a wheel, and the wind drag goes up.
>
> Reduce the wheel's wind drag, and the weight rises.
>
> As Frank points out, the aero advantage tends to be much larger and
> more practical than the weight advantage.

The initial argument was aero vs inertia. In that case aero always
wins. But in aero vs weight it's not so clear cut.

Joseph

carlfogel@comcast.net

01-03-1970, 08:42 PM

On Tue, 27 Nov 2007 00:41:47 -0800 (PST),
"joseph.santaniello@gmail.com" <joseph.santaniello@gmail.com> wrote:

>On Nov 27, 12:58 am, carlfo...@comcast.net wrote:
>
>> Carve weight off a wheel, and the wind drag goes up.
>>
>> Reduce the wheel's wind drag, and the weight rises.
>>
>> As Frank points out, the aero advantage tends to be much larger and
>> more practical than the weight advantage.
>
>The initial argument was aero vs inertia. In that case aero always
>wins. But in aero vs weight it's not so clear cut.
>
>Joseph

Dear Joseph,

Can you think of a reasonably normal example in which trading
aerodynamics for lighter wheels will not produce slower times?

Climbing the Alp d'Huez should favor the lighter wheel.

A short sprint may favor the lighter wheel.

But just about any normal paved course should favor aero.

Of course, there are light aero wheels. But you can use less of the
same material to shape an even lighter wheel. Since it won't be as
aerodynamic, it should be slower for most courses.

In broad terms, that's why the Varna Diablo weighs as much as four
normal bicycles, but can exceed 80 mph. In practical terms, wind drag
trumps weight on just about anything but a steep climb.

Cheers,

Carl Fogel

SocSecTrainWreck@earthlink.net

01-03-1970, 08:42 PM

On Nov 27, 3:41 am, "joseph.santanie...@gmail.com"
<joseph.santanie...@gmail.com> wrote:
> On Nov 27, 12:58 am, carlfo...@comcast.net wrote:
>
> > Carve weight off a wheel, and the wind drag goes up.
>
> > Reduce the wheel's wind drag, and the weight rises.
>
> > As Frank points out, the aero advantage tends to be much larger and
> > more practical than the weight advantage.
>
> The initial argument was aero vs inertia. In that case aero always
> wins. But in aero vs weight it's not so clear cut.

Not exactly. Aero doesn't always win; the model is difficult, but in
some situations where there is a lot of acceleration, rotating mass
could be more important. I don't think that aero beats rotating mass
in a criterium. In the first place, with most massed start races aero
loses much of its advantage because you are frequently riding in
someone's slipstream. But, regardless, the amount of acceleration is
essentially many, many times what it is in Fogel's pursuit race that
showed an aero advantage. You can even see how it could be affected by
racing tactics- two racers of the same fitness, one with lighter
wheels, one with more aero wheels get the same leadout. The person
with the more aero wheels wants to try to come off the leadout sooner,
the one with the lighter, less aero wheels wants to sprint later and
build up enough of a lead that it can't be overcome by the aero rider
before the finish line. Personally, for a criterium, given the choice
of alloy 500g aero rims or 320g classic box section rims, I would take
the latter.

This is why people buy carbon wheels- you get aero and you get low
rotating mass. My point is not that low rotating mass is better than
aero, it's that low rotating mass in not so unimportant that it can be
ignored for competition; it seemed to be suggested that it was
essentially insignificant. If you're looking for one more watt so that
you can win your TT, get some carbon aero wheels.

joseph.santaniello@gmail.com

01-03-1970, 08:42 PM

On Nov 27, 10:34 am, carlfo...@comcast.net wrote:
> On Tue, 27 Nov 2007 00:41:47 -0800 (PST),
>
> "joseph.santanie...@gmail.com" <joseph.santanie...@gmail.com> wrote:
> >On Nov 27, 12:58 am, carlfo...@comcast.net wrote:
>
> >> Carve weight off a wheel, and the wind drag goes up.
>
> >> Reduce the wheel's wind drag, and the weight rises.
>
> >> As Frank points out, the aero advantage tends to be much larger and
> >> more practical than the weight advantage.
>
> >The initial argument was aero vs inertia. In that case aero always
> >wins. But in aero vs weight it's not so clear cut.
>
> >Joseph
>
> Dear Joseph,
>
> Can you think of a reasonably normal example in which trading
> aerodynamics for lighter wheels will not produce slower times?
>
> Climbing the Alp d'Huez should favor the lighter wheel.
>
> A short sprint may favor the lighter wheel.
>
> But just about any normal paved course should favor aero.
>
> Of course, there are light aero wheels. But you can use less of the
> same material to shape an even lighter wheel. Since it won't be as
> aerodynamic, it should be slower for most courses.
>
> In broad terms, that's why the Varna Diablo weighs as much as four
> normal bicycles, but can exceed 80 mph. In practical terms, wind drag
> trumps weight on just about anything but a steep climb.
>
> Cheers,
>
> Carl Fogel

In a mass start race, light can be more important that aero, even on
just a rolling course.

I race (or at least participate in...) races that usually are 5 laps
of about 15km with usually 2 semi-difficult hills per lap. Standard
operating procedure is for me to get dropped on hill 2 of lap 2. My
buddies email me their GPS plots after the races and invariably the
pace calms down (at least for a while) somewhat shortly after I get
dropped. I always finish the races, but the last few laps are just an
exercise to see how much I can limit the gap. Aero would help here,
but at this point, who cares?

If I crest the hill 20m back from the group and I've got hydrogen ions
coming out of my ears, and I've been at max hr for the last 30 seconds
or so, no amount of aero is going to allow me to pull them back. If my
bike/body is a shade lighter, I may be able to crest the hill with the
group. Then I'm sitting pretty until the next hill. If I get all the
way to the finish, I'm ready to administer some serious punishment to
those who made me suffer on the hills.

Joseph

dustoyevsky@mac.com

01-03-1970, 08:42 PM

On Nov 27, 3:34 am, carlfo...@comcast.net wrote:

> Dear Joseph,
>
> Can you think of a reasonably normal example in which trading
> aerodynamics for lighter wheels will not produce slower times?
>
> Climbing the Alp d'Huez should favor the lighter wheel.
>
> A short sprint may favor the lighter wheel.
>
> But just about any normal paved course should favor aero.
>
> Of course, there are light aero wheels. But you can use less of the
> same material to shape an even lighter wheel. Since it won't be as
> aerodynamic, it should be slower for most courses.

(butting in to propose an answer)

Do I have "numbers"? No. Just a guess for your question: Riding a
tight crit, being very good (and a little lucky) at sitting tight on
the right wheels, where you're only bucking the wind for maybe 200
yards while you storm to a crushing victory. (real answer: pack
riding) --D-y

carlfogel@comcast.net

01-03-1970, 08:42 PM

On Tue, 27 Nov 2007 03:23:05 -0800 (PST),
"joseph.santaniello@gmail.com" <joseph.santaniello@gmail.com> wrote:

>On Nov 27, 10:34 am, carlfo...@comcast.net wrote:
>> On Tue, 27 Nov 2007 00:41:47 -0800 (PST),
>>
>> "joseph.santanie...@gmail.com" <joseph.santanie...@gmail.com> wrote:
>> >On Nov 27, 12:58 am, carlfo...@comcast.net wrote:
>>
>> >> Carve weight off a wheel, and the wind drag goes up.
>>
>> >> Reduce the wheel's wind drag, and the weight rises.
>>
>> >> As Frank points out, the aero advantage tends to be much larger and
>> >> more practical than the weight advantage.
>>
>> >The initial argument was aero vs inertia. In that case aero always
>> >wins. But in aero vs weight it's not so clear cut.
>>
>> >Joseph
>>
>> Dear Joseph,
>>
>> Can you think of a reasonably normal example in which trading
>> aerodynamics for lighter wheels will not produce slower times?
>>
>> Climbing the Alp d'Huez should favor the lighter wheel.
>>
>> A short sprint may favor the lighter wheel.
>>
>> But just about any normal paved course should favor aero.
>>
>> Of course, there are light aero wheels. But you can use less of the
>> same material to shape an even lighter wheel. Since it won't be as
>> aerodynamic, it should be slower for most courses.
>>
>> In broad terms, that's why the Varna Diablo weighs as much as four
>> normal bicycles, but can exceed 80 mph. In practical terms, wind drag
>> trumps weight on just about anything but a steep climb.
>>
>> Cheers,
>>
>> Carl Fogel
>
>In a mass start race, light can be more important that aero, even on
>just a rolling course.
>
>I race (or at least participate in...) races that usually are 5 laps
>of about 15km with usually 2 semi-difficult hills per lap. Standard
>operating procedure is for me to get dropped on hill 2 of lap 2. My
>buddies email me their GPS plots after the races and invariably the
>pace calms down (at least for a while) somewhat shortly after I get
>dropped. I always finish the races, but the last few laps are just an
>exercise to see how much I can limit the gap. Aero would help here,
>but at this point, who cares?
>
>If I crest the hill 20m back from the group and I've got hydrogen ions
>coming out of my ears, and I've been at max hr for the last 30 seconds
>or so, no amount of aero is going to allow me to pull them back. If my
>bike/body is a shade lighter, I may be able to crest the hill with the
>group. Then I'm sitting pretty until the next hill. If I get all the
>way to the finish, I'm ready to administer some serious punishment to
>those who made me suffer on the hills.
>
>Joseph

Dear Joseph,

Sorry, but I got lost in the first sentence about mass starts somehow
favoring lighter wheels over aero wheels. They favor it for about the
length of time it takes the rider to get up to racing speed.

Calculators predict that reasonable aero will be roughly an order of
magnitude more important than reasonable light, with aero saving 12
seconds in a 4 km TT versus 0.7 seconds for light. What follows is
what I posted earlier in this thread.

You can use the Analytic Cycling wind page to calculate some wheel
effects--leave the wind alone, use identical wheels, and then reduce
the weight of one wheel set:

http://www.analyticcycling.com/DiffEqWindCourse_Page.html

I tried a pair of G36 wheels, changing the weight to match, and the
calculator predicted 466.98 seconds for both.

Take 200 grams off each wheel on one bike, and the time drops to
466.29 seconds, about 7/10ths of a second faster for the slightly
lighter bike that accelerates slightly faster on a theoretical 4 km TT
course with no theoretical braking.

In contrast, slightly heavier wheels with better aerodynamics (the
default for the right-hand bike) can take about 12 seconds off the
same time.

As for your convoluted description of getting dropped on lap 2 on the
hill of a 5 lap 15 km course, I'm sorry, but I suspect that you're
going to get dropped no matter what your equipment is. They're just
faster. If they can drop you on lap 2 of a 5 lap race, it's probably
not because you forgot and left your water bottle on the bike.

In any case, pursuing 400 gram lighter wheels for 0.7 seconds in 4 km
is not likely to be as helpful as pursuing 12 seconds improvement
through aero.

As Frank points out, aero is likely to help for almost the entire
race, while shaving grams off wheels helps only when accelerating,
which isn't something that bicycles do for much of a typical race, or
when climbing, which isn't most of your race.

I wish that taking a pound off your wheels would let you keep up with
your friends on the climb, but take a look at a calculator, plug in
some figures that describe your weight, the slope, and the distance,
and see if

For fun, you could ask your friends to carry a 1 kg weight (or
whatever difference you _might_ get with amazingly lighter wheels),
but they'll probably keep dropping you.

Cheers,

Carl Fogel

frkrygow@gmail.com

01-03-1970, 08:42 PM

On Nov 27, 8:22 am, "dustoyev...@mac.com" <dustoyev...@mac.com> wrote:
> On Nov 26, 11:45 am, frkry...@gmail.com wrote:
>
> > You'd better decide whether you're talking about racing or not.
>
> YOU'RE the one who brought racing into the discussion.

Nope. Not so. Both Carl Fogel and SocSecTrainWreck mentioned it
earlier than I did. Check the posts. I was merely following the
course of the conversation.

>
> (In reaction to the typical snotty Frank Krygowski-style "you'd
> better blah blah blah).

<sigh> D-y, you've got a knack for misinterpreting my tone, plus an
incredible chip on your shoulder! I had nothing "snotty" in mind when
I replied to you, and nothing in my tone was intended to sound that
way.

If you can't stand even mild disagreement, you shouldn't be posting to
Usenet.

No, wait! Strike that! Replace it with:

In my humble and respectful opinion, if mild disagreement disturbs and/
or distresses you, you might want to consider finding another way to
pass your time. Your interpretation of Usenet posts may possibly
induce unpleasant negative emotions, and I certainly wouldn't want any
unpleasantness at all to befall such a nice guy! ;-)

> > If you're
> > not, neither a small reduction in wheel inertia nor a small
> > reduction in wheel aero drag matter, so the tradeoff between the two
> > is moot.
>
> Moot? You seem to want to think so. Other people might not, for
> obvious reasons.

Of course others may think differently. And, for a given set of
criteria, one side might be right and the other side wrong. So why
not deal with the facts, instead of taking offense at any
disagreement?

>
> > If you are talking about racing, you'd _better_ be riding over "15mph
> > or so." And then, that tradeoff goes in favor of aero, not less
> > inertia.
>
> Unless we're going up a long, steep climb. That's why people who can
> spend a comparatively large sum on the lightest wheel they can get
> with the most aero in it.

Sorry, but "the lightest wheel with the most aero" is not what I was
talking about - because it doesn't exist. I was discussing the
tradeoff between two conflicting benefits.

>
> > We also need to review the concept of "negligible." Do you shave off
> > your arm hair before a road race? I never did, even though I know it
> > would have "helped" at some level. Some effects really do disappear
> > in the noise.
>
> Typical Krygowsky rhetoric. Attempt to ridicule, set up a straw man.

Nope, attempt to illustrate. Failed attempt, I see.

The point is, small theoretical performance benefits are not reliable,
and are often negligible. That includes minor aerodynamic
advantages. (Remember Shimano Aero groups, or whatever they were
called? Where are they now? Why didn't they stick around?)

And in most riding done with an objective of even moderate speed or
distance, inertia changes are less valuable than aerodynamic changes
of equal magnitude.

>
> You still didn't make that seven seconds for 40k go away, Frank.

If you want to theoretically "prove" the seven second benefit in the
context of what I've been saying, here's what you do: You spec two
wheelsets, one with a bit less inertia and a bit more aero drag
compared to the other wheelset. Ideally, make the differences of
equal percentage magnitude (i.e. 5% less inertia, 5% more drag). And
since we're talking inertia (vs weight), adjust the weight of the bike
+rider to keep it constant.

Put those two bikes into one of the bike performance calculators.
Report back on which is faster over the 40k time trial.

I think you'll find the seven seconds goes away very nicely. The aero
advantage on the bike with more slippery wheels will more than consume
the inertia disadvantage.

If that were not so, these guys http://en.wikipedia.org/wiki/Individual_time_trial
would be stripping off those high-inertia rear disks.

- Frank Krygowski

carlfogel@comcast.net

01-03-1970, 08:42 PM

On Tue, 27 Nov 2007 05:48:45 -0800 (PST), "dustoyevsky@mac.com"
<dustoyevsky@mac.com> wrote:

>On Nov 27, 3:34 am, carlfo...@comcast.net wrote:
>
>> Dear Joseph,
>>
>> Can you think of a reasonably normal example in which trading
>> aerodynamics for lighter wheels will not produce slower times?
>>
>> Climbing the Alp d'Huez should favor the lighter wheel.
>>
>> A short sprint may favor the lighter wheel.
>>
>> But just about any normal paved course should favor aero.
>>
>> Of course, there are light aero wheels. But you can use less of the
>> same material to shape an even lighter wheel. Since it won't be as
>> aerodynamic, it should be slower for most courses.
>
>(butting in to propose an answer)
>
>Do I have "numbers"? No. Just a guess for your question: Riding a
>tight crit, being very good (and a little lucky) at sitting tight on
>the right wheels, where you're only bucking the wind for maybe 200
>yards while you storm to a crushing victory. (real answer: pack
>riding) --D-y

Dear D,

I sympathize, but it still sounds like wishful thinking.

"If only I'd drained my bladder right there at the starting line and
gotten rid of those extra few drops, I'd have been light enough to
pass those guys who somehow stayed ahead of me for the first 14,800
meters. It can't be that they're faster than I am."

"Hmmm . . . maybe if I ride without socks, the reduction in rotating
mass at the pedals will give me the acceleration that I need?"

I wonder how much people think that they're accelerating in that last
200 yards?

Cheers,

Carl Fogel

dustoyevsky@mac.com

01-03-1970, 08:43 PM

On Nov 27, 2:34 pm, frkry...@gmail.com wrote:

> Nope. Not so. Both Carl Fogel and SocSecTrainWreck mentioned it
> earlier than I did. Check the posts. I was merely following the
> course of the conversation.

Right. My bad. I apologize.

> <sigh> D-y, you've got a knack for misinterpreting my tone,

No.

> plus an
> incredible chip on your shoulder!

That's one of my good qualities.

> I had nothing "snotty" in mind when
> I replied to you, and nothing in my tone was intended to sound that
> way.

Thank you, Frank.

> If you can't stand even mild disagreement, you shouldn't be posting to
> Usenet.

I can stand it just fine.

> No, wait! Strike that! Replace it with:
>
> In my humble and respectful opinion, if mild disagreement disturbs and/
> or distresses you, you might want to consider finding another way to
> pass your time. Your interpretation of Usenet posts may possibly
> induce unpleasant negative emotions, and I certainly wouldn't want any
> unpleasantness at all to befall such a nice guy! ;-)

Good one, Frank. I'm sure it was unpleasant to be yelled at, so to
speak. I apologized for the misattribution, but not for the comments
(or delivery volume) about the tenor of your posts, for all your
assurances of intent. Sue me? (Dang, there's that foreign object on my
shoulder-- nope, it's not an epaulette! Way too much wood grain!)

> Of course others may think differently. And, for a given set of
> criteria, one side might be right and the other side wrong. So why
> not deal with the facts, instead of taking offense at any
> disagreement?

Fire away. There isn't any "wrong" about the seven seconds, unless the
math is faulty. I expect it's a minimum, did I say?

> > > If you are talking about racing, you'd _better_ be riding over "15mph
> > > or so." And then, that tradeoff goes in favor of aero, not less
> > > inertia.
>
> > Unless we're going up a long, steep climb. That's why people who can
> > spend a comparatively large sum on the lightest wheel they can get
> > with the most aero in it.

> Sorry, but "the lightest wheel with the most aero" is not what I was
> talking about - because it doesn't exist. I was discussing the
> tradeoff between two conflicting benefits.

Obviously (but I'll explain) meant to say "the best compromise between
aero and weight they can get".

Here's a pic of wheels that have had obvious attention paid to light
and aero:

<http://www.cyclingnews.com/photos/2007/tech/features/
tour_lance_bikes07/Armstrong_Trek_1999_closeup.jpg>

Looks like "light" won out, there. I'd say that's at a sharp point of
spending money to go fast uphill-- maybe not the best solution, but
from reports, we could expect some fussy picking and choosing has
occurred here.

> The point is, small theoretical performance benefits are not reliable,

That is the point (finally). No, if you keep the lighter wheels on,
that advantage is always there. Breakfast is elsewhere.

> and are often negligible.

Seven seconds every 40k? Real. Then there's the value judgement, which
you're reaching for with "negligible".

> That includes minor aerodynamic
> advantages. (Remember Shimano Aero groups, or whatever they were
> called? Where are they now? Why didn't they stick around?)

Because the brakes sucked. That and "New! Improved!" marketing for
following years.

> And in most riding done with an objective of even moderate speed or
> distance, inertia changes are less valuable than aerodynamic changes
> of equal magnitude.

We know, Frank.

(I adjusted the chip on my shoulder and stated):
> > You still didn't make that seven seconds for 40k go away, Frank.

(reply):
> If you want to theoretically "prove" the seven second benefit in the
> context of what I've been saying, here's what you do:

(Excuse me):
Send someone else on your errands, Frank.

> You spec two
> wheelsets, one with a bit less inertia and a bit more aero drag
> compared to the other wheelset. Ideally, make the differences of
> equal percentage magnitude (i.e. 5% less inertia, 5% more drag). And
> since we're talking inertia (vs weight), adjust the weight of the bike
> +rider to keep it constant.
>
> Put those two bikes into one of the bike performance calculators.
> Report back on which is faster over the 40k time trial.

> I think you'll find the seven seconds goes away very nicely. The aero
> advantage on the bike with more slippery wheels will more than consume
> the inertia disadvantage.

I already said that in a lot fewer words, and everybody already knows
in the first place.

The seven seconds for the first comparison, between two sets of
wheels, one a certain amount lighter than the other, is still there
and will never, ever "go away". You want to drag one more or a
thousand more wheels into the comparison, fine. The numbers are still
there.

There's something that really bugs you about that seven seconds,
besides the fact that they won't go away.

Think about that and report back, will you, Frank? (That's what I'm
waiting for here.)

> If that were not so, these guyshttp://en.wikipedia.org/wiki/Individual_time_trial
> would be stripping off those high-inertia rear disks.

That's just being silly. No, really.

I'm not going to lead you any further. What's wrong with the lighter
wheels, in plain talk? Come on, you can do it! --D-y

joseph.santaniello@gmail.com

01-03-1970, 08:43 PM

On Nov 27, 9:34 pm, carlfo...@comcast.net wrote:
> On Tue, 27 Nov 2007 03:23:05 -0800 (PST),
>
>
>
> "joseph.santanie...@gmail.com" <joseph.santanie...@gmail.com> wrote:
> >On Nov 27, 10:34 am, carlfo...@comcast.net wrote:
> >> On Tue, 27 Nov 2007 00:41:47 -0800 (PST),
>
> >> "joseph.santanie...@gmail.com" <joseph.santanie...@gmail.com> wrote:
> >> >On Nov 27, 12:58 am, carlfo...@comcast.net wrote:
>
> >> >> Carve weight off a wheel, and the wind drag goes up.
>
> >> >> Reduce the wheel's wind drag, and the weight rises.
>
> >> >> As Frank points out, the aero advantage tends to be much larger and
> >> >> more practical than the weight advantage.
>
> >> >The initial argument was aero vs inertia. In that case aero always
> >> >wins. But in aero vs weight it's not so clear cut.
>
> >> >Joseph
>
> >> Dear Joseph,
>
> >> Can you think of a reasonably normal example in which trading
> >> aerodynamics for lighter wheels will not produce slower times?
>
> >> Climbing the Alp d'Huez should favor the lighter wheel.
>
> >> A short sprint may favor the lighter wheel.
>
> >> But just about any normal paved course should favor aero.
>
> >> Of course, there are light aero wheels. But you can use less of the
> >> same material to shape an even lighter wheel. Since it won't be as
> >> aerodynamic, it should be slower for most courses.
>
> >> In broad terms, that's why the Varna Diablo weighs as much as four
> >> normal bicycles, but can exceed 80 mph. In practical terms, wind drag
> >> trumps weight on just about anything but a steep climb.
>
> >> Cheers,
>
> >> Carl Fogel
>
> >In a mass start race, light can be more important that aero, even on
> >just a rolling course.
>
> >I race (or at least participate in...) races that usually are 5 laps
> >of about 15km with usually 2 semi-difficult hills per lap. Standard
> >operating procedure is for me to get dropped on hill 2 of lap 2. My
> >buddies email me their GPS plots after the races and invariably the
> >pace calms down (at least for a while) somewhat shortly after I get
> >dropped. I always finish the races, but the last few laps are just an
> >exercise to see how much I can limit the gap. Aero would help here,
> >but at this point, who cares?
>
> >If I crest the hill 20m back from the group and I've got hydrogen ions
> >coming out of my ears, and I've been at max hr for the last 30 seconds
> >or so, no amount of aero is going to allow me to pull them back. If my
> >bike/body is a shade lighter, I may be able to crest the hill with the
> >group. Then I'm sitting pretty until the next hill. If I get all the
> >way to the finish, I'm ready to administer some serious punishment to
> >those who made me suffer on the hills.
>
> >Joseph
>
> Dear Joseph,
>
> Sorry, but I got lost in the first sentence about mass starts somehow
> favoring lighter wheels over aero wheels. They favor it for about the
> length of time it takes the rider to get up to racing speed.

> Calculators predict that reasonable aero will be roughly an order of
> magnitude more important than reasonable light, with aero saving 12
> seconds in a 4 km TT versus 0.7 seconds for light. What follows is
> what I posted earlier in this thread.
>
> You can use the Analytic Cycling wind page to calculate some wheel
> effects--leave the wind alone, use identical wheels, and then reduce
> the weight of one wheel set:
>
> http://www.analyticcycling.com/DiffEqWindCourse_Page.html
>
> I tried a pair of G36 wheels, changing the weight to match, and the
> calculator predicted 466.98 seconds for both.
>
> Take 200 grams off each wheel on one bike, and the time drops to
> 466.29 seconds, about 7/10ths of a second faster for the slightly
> lighter bike that accelerates slightly faster on a theoretical 4 km TT
> course with no theoretical braking.
>
> In contrast, slightly heavier wheels with better aerodynamics (the
> default for the right-hand bike) can take about 12 seconds off the
> same time.
>
> As for your convoluted description of getting dropped on lap 2 on the
> hill of a 5 lap 15 km course, I'm sorry, but I suspect that you're
> going to get dropped no matter what your equipment is. They're just
> faster. If they can drop you on lap 2 of a 5 lap race, it's probably
> not because you forgot and left your water bottle on the bike.
>
> In any case, pursuing 400 gram lighter wheels for 0.7 seconds in 4 km
> is not likely to be as helpful as pursuing 12 seconds improvement
> through aero.
>
> As Frank points out, aero is likely to help for almost the entire
> race, while shaving grams off wheels helps only when accelerating,
> which isn't something that bicycles do for much of a typical race, or
> when climbing, which isn't most of your race.

I agree that aero wheels would make the total energy use in a race be
lower. But that doesn't matter. If I'm sitting on a wheel using 72% of
my capacity or 77% makes no difference. But when I am at 100% on the
verge of being dropped it makes a huge difference. On a hill if I
crest with the group, I'm still in the race, if I'm off the back it's
curtains.

If I crest 5 seconds back on a 1km or so 6% hill that I maybe averaged
400W on, how much weight would I need to lose to stay with the group?
And since I got dropped halfway, I lost drafting too. Ignoring the
drafting part I'd need to lose 2kg. With the drafting effects, it'll
be less. So in theory maybe 1.5kg _could_ tip the scales for me.

> I wish that taking a pound off your wheels would let you keep up with
> your friends on the climb, but take a look at a calculator, plug in
> some figures that describe your weight, the slope, and the distance,
> and see if

I have. It isn't any sort of gaurantee I can hang, but it makes it
somewhat more of a possibility.

> For fun, you could ask your friends to carry a 1 kg weight (or
> whatever difference you _might_ get with amazingly lighter wheels),
> but they'll probably keep dropping you.

Actually we have done this. On our hill interval hill some guys have
carried 4 full water bottles and one guy even had a backpack with
dumbells in it! The water bottles made some difference, but it's
ineviatable that I will be dropped on hills, if the hill is long
enough. With weights approaching mine using the dumbells, they all got
stomped despite having higher power output than I. They were just not
used to the weight and the type of resistance it brings (low "crank
inertia").

Joseph

> Cheers,
>
> Carl Fogel

SocSecTrainWreck@earthlink.net

01-03-1970, 08:43 PM

On Nov 27, 3:34 pm, carlfo...@comcast.net wrote:
> On Tue, 27 Nov 2007 03:23:05 -0800 (PST),
> Sorry, but I got lost in the first sentence about mass starts somehow
> favoring lighter wheels over aero wheels. They favor it for about the
> length of time it takes the rider to get up to racing speed.

You seem to be under a complete misconception about the nature of
massed start racing. In those situations where you have a constant
speed you are likely to be in someone's slipstream and going at a rate
that is not necessarily that strenuous. Even in a break the ability to
respond instantly to an attack will be more important than the
advantage of aero wheels when you are pulling. On level ground if you
lose contact with a break, your chances of getting back on thanks to
your aero wheels are nil, but you might avoid the problem if you can
respond quickly enough that you don't lose contact in the first place.
And if the pace becomes serious in the peloton, you are constantly
"getting up to racing speed". As I said before, your theoretical
example is only found in the real world on the track.

But to reiterate my earlier point: it's best to have light, aero rims.
That's why people have carbon rims. They may be fashionable, expensive
and less reliable, but they are also the fastest. Those who don't have
them may want to rationalize their deficiency by saying the weight
doesn't matter, but it does. Find another excuse, because there are
better ones.

dustoyevsky@mac.com

01-03-1970, 08:44 PM

On Nov 27, 2:45 pm, carlfo...@comcast.net wrote:

> I sympathize,

No need. I've been beaten by some pretty good riders.

> but it still sounds like wishful thinking.

> "If only I'd drained my bladder right there at the starting line and
> gotten rid of those extra few drops, I'd have been light enough to
> pass those guys who somehow stayed ahead of me for the first 14,800
> meters. It can't be that they're faster than I am."

Not ever.

> "Hmmm . . . maybe if I ride without socks, the reduction in rotating
> mass at the pedals will give me the acceleration that I need?"

Come on, CF.

> I wonder how much people think that they're accelerating in that last
> 200 yards?

Hard as they can.

How much energy did they manage to save for that blast since the race
started, is the question.

Maybe it exists, I just don't see people who are deluded about
benefits of equipment advantages-- especially when "the other guys"
all have similar stuff. --D-y

carlfogel@comcast.net

01-03-1970, 08:44 PM

On Tue, 27 Nov 2007 13:05:10 -0800 (PST),
"joseph.santaniello@gmail.com" <joseph.santaniello@gmail.com> wrote:

[snip]

>> For fun, you could ask your friends to carry a 1 kg weight (or
>> whatever difference you _might_ get with amazingly lighter wheels),
>> but they'll probably keep dropping you.
>
>Actually we have done this. On our hill interval hill some guys have
>carried 4 full water bottles and one guy even had a backpack with
>dumbells in it! The water bottles made some difference, but it's
>inevitable that I will be dropped on hills, if the hill is long
>enough. With weights approaching mine using the dumbells, they all got
>stomped despite having higher power output than I. They were just not
>used to the weight and the type of resistance it brings (low "crank
>inertia").
>
>Joseph
>
>> Cheers,
>>
>> Carl Fogel

Dear Joseph,

If you're racing on wheels that can be lightened by the equivalent of
a backpack loaded with dumbbells, you must have started with some
awfully strange wheels.

Cheers,

Carl Fogel

Jay Beattie

01-03-1970, 08:44 PM

On Nov 27, 3:28 pm, carlfo...@comcast.net wrote:
> On Tue, 27 Nov 2007 13:05:10 -0800 (PST),
>
> "joseph.santanie...@gmail.com" <joseph.santanie...@gmail.com> wrote:
>
> [snip]
>
>
>
>
>
> >> For fun, you could ask your friends to carry a 1 kg weight (or
> >> whatever difference you _might_ get with amazingly lighter wheels),
> >> but they'll probably keep dropping you.
>
> >Actually we have done this. On our hill interval hill some guys have
> >carried 4 full water bottles and one guy even had a backpack with
> >dumbells in it! The water bottles made some difference, but it's
> >inevitable that I will be dropped on hills, if the hill is long
> >enough. With weights approaching mine using the dumbells, they all got
> >stomped despite having higher power output than I. They were just not
> >used to the weight and the type of resistance it brings (low "crank
> >inertia").
>
> >Joseph
>
> >> Cheers,
>
> >> Carl Fogel
>
> Dear Joseph,
>
> If you're racing on wheels that can be lightened by the equivalent of
> a backpack loaded with dumbbells, you must have started with some
> awfully strange wheels.

Moser's hour record wheels. Great on the flats. Lousy in the hills.

I know saving weight makes a difference climbing but cannot say at
what point, i.e., a gram, a kilo, etc. Throwing Ti bits and pieces on
my SP frame back in the day made absolutely no difference. Switching
to an AL bike with a CF fork made a big difference (until everyone
changed to lighter equipment). Light wheels with sew-ups made a
difference, but that was back in the day when my training clinchers
were first generation Turbos and rode like rocks. I also know that in
the waning days of my long and ignoble racing career, I tried all
sorts of weight saving measures (ounces) to avoid being shelled on the
climbs. None worked. I had to turn to clever tactics, like avoiding
hilly road races populated by 120lb climbers who were 20 years younger
than me.

I just dropped 20lbs and find it easier to climb, but I don't feel
like my over-all speed is that much higher. Climbing is just less
taxing, and I have a sprint at the top again. I could probably dump
my old fat self by a couple of bike lengths on a 1K climb. Maybe if I
got uber-light wheels, I could dump myself by three bike lengths! No
matter what, I would still be looking at the backside of my usual
riding buddy who will always kick my ass. -- Jay Beattie.

joseph.santaniello@gmail.com

01-03-1970, 08:44 PM

On Nov 28, 12:28 am, carlfo...@comcast.net wrote:
> On Tue, 27 Nov 2007 13:05:10 -0800 (PST),
>
> "joseph.santanie...@gmail.com" <joseph.santanie...@gmail.com> wrote:
>
> [snip]
>
>
>
> >> For fun, you could ask your friends to carry a 1 kg weight (or
> >> whatever difference you _might_ get with amazingly lighter wheels),
> >> but they'll probably keep dropping you.
>
> >Actually we have done this. On our hill interval hill some guys have
> >carried 4 full water bottles and one guy even had a backpack with
> >dumbells in it! The water bottles made some difference, but it's
> >inevitable that I will be dropped on hills, if the hill is long
> >enough. With weights approaching mine using the dumbells, they all got
> >stomped despite having higher power output than I. They were just not
> >used to the weight and the type of resistance it brings (low "crank
> >inertia").
>
> >Joseph
>
> >> Cheers,
>
> >> Carl Fogel
>
> Dear Joseph,
>
> If you're racing on wheels that can be lightened by the equivalent of
> a backpack loaded with dumbbells, you must have started with some
> awfully strange wheels.
>
> Cheers,
>
> Carl Fogel

They are solid lead. Actually I was just going off on a tangent about
how smaller riders with higher power outputs under normal
circumstances, are not able to put that power to the same effect when
they have a huge weight to carry.

But as far as the weight of wheels goes, when I did the experiment on
our hill repeat day, I tried to stay with a guy I can almost stay with
up shorter hills, and as usual I couldn't. We tried with him carrying
two water bottles and me none (he took mine), and I could stay a
little longer. Not long enough, but longer.

But it still remains that very little weight can make a big difference
if it means the difference between being able to stay with the group
or not.

At the start of a climb, I am usually quite near the front. This way I
can fall through the whole peloton, and hopefully still be in contact
at the top. I lose time to the front guys, but since the peloten takes
some time to pass, I get a buffer. Since the peloton stretches out on
hills, I have maybe 5 seconds I can affort to lose to the front
runners yet still be in the pack and still be able to draft. If I lose
contact before the top I lose my draft and I start falling even
further behind so my 5 seconds further back would have been the same
as maybe 2 seconds were the peloton larger and I still had a draft. So
maybe I'm really only 2 seconds too slow up a 1km hill. That's not
much weight.

The wheels in question (not quite barbell territory, but still a big
difference):

6600 hubs, Velocity Deep-V 28 and 32, DT Competition, brass, Vittoria
Pave, Continental tubes
vs
AC hubs, Mavic Oro-10 28, DT Revolution, alloy, Veloflex Criterium

Joseph

carlfogel@comcast.net

01-03-1970, 08:44 PM

On Tue, 27 Nov 2007 16:06:08 -0800 (PST), "dustoyevsky@mac.com"
<dustoyevsky@mac.com> wrote:

[snip]

>I'm not going to lead you any further. What's wrong with the lighter
>wheels, in plain talk? Come on, you can do it! --D-y

Dear D,

Er, they're slower than heavier, more aerodynamic wheels?

Cheers,

Carl Fogel

frkrygow@gmail.com

01-03-1970, 08:44 PM

On Nov 27, 7:06 pm, "dustoyev...@mac.com" <dustoyev...@mac.com> wrote:
> On Nov 27, 2:34 pm, frkry...@gmail.com wrote:
>
> > Nope. Not so. Both Carl Fogel and SocSecTrainWreck mentioned it
> > earlier than I did. Check the posts. I was merely following the
> > course of the conversation.
>
> Right. My bad. I apologize.

Accepted.

> > <sigh> D-y, you've got a knack for misinterpreting my tone,
>
> No.

Ah. Yet, as I recall, this is not the first time you've laced into me
for what I intended as a mild post. Sorry, but I simply don't believe
you know the tone I intend better than I do.

> > I had nothing "snotty" in mind when
> > I replied to you, and nothing in my tone was intended to sound that
> > way.
>
> Thank you, Frank.

You're welcome.

> Good one, Frank. I'm sure it was unpleasant to be yelled at, so to
> speak. I apologized for the misattribution, but not for the comments
> (or delivery volume) about the tenor of your posts, for all your
> assurances of intent. Sue me?

No, just reduce my estimation of your judgment.

> > Sorry, but "the lightest wheel with the most aero" is not what I was
> > talking about - because it doesn't exist. I was discussing the
> > tradeoff between two conflicting benefits.
>
> Obviously (but I'll explain) meant to say "the best compromise between
> aero and weight they can get".

Sorry, but that was _not_ obvious. And it both sidesteps the point I
was making, and greatly exceeds the point you were making.

To explain: First, I was describing the typical tradeoff between
wheel aerodynamics and wheel inertia, and I believe I made that
clear. The extreme examples were the photos showing pro time trialers
using wheels of very high inertia. Obviously, the people betting the
most money on this are choosing an aero advantage, despite an inertia
disadvantage. They are doing exactly what I said should be done.

Second, your claim that you _really_ meant "the best compromise" is an
admission that you expressed yourself very poorly. It's also too
simplistic to be meaningful. IOW, of _course_ one should use "the
best compromise." But the "best compromise" for a time trial will be
a wheel with more inertia than the typical light wheel, and less aero
drag than that typical light wheel. The same is true for most types
of racing. (For rides other than racing, the question is moot, as I
said.)

> Here's a pic of wheels that have had obvious attention paid to light
> and aero:
>
> <http://www.cyclingnews.com/photos/2007/tech/features/
> tour_lance_bikes07/Armstrong_Trek_1999_closeup.jpg>
>
> Looks like "light" won out, there. I'd say that's at a sharp point of
> spending money to go fast uphill-- maybe not the best solution, but
> from reports, we could expect some fussy picking and choosing has
> occurred here.

And what, specifically, are you recommending? That every competitive
rider should use exactly those wheels? Even when _not_ designing a
bike specialized for steep mountain climbing competition?

Are you implying that these guys http://www.fascatcoaching.com/f_one.html
don't know what they're talking about? Note, Scott Daubert's job was
to make Lance faster in time trials.

Why didn't the article focus on wheel inertia instead? Why doesn't
the photo show light wheels?

> > And in most riding done with an objective of even moderate speed or
> > distance, inertia changes are less valuable than aerodynamic changes
> > of equal magnitude.
>
> We know, Frank.

And yet, your posts argued to the contrary. Either you didn't know,
or that chip is weighing very heavily on your shoulder.

> > > You still didn't make that seven seconds for 40k go away, Frank.
>
> > If you want to theoretically "prove" the seven second benefit in the
> > context of what I've been saying, here's what you do: You spec two
> > wheelsets, one with a bit less inertia and a bit more aero drag
> > compared to the other wheelset. Ideally, make the differences of
> > equal percentage magnitude (i.e. 5% less inertia, 5% more drag). And
> > since we're talking inertia (vs weight), adjust the weight of the bike
> > +rider to keep it constant.
>
> > Put those two bikes into one of the bike performance calculators.
> > Report back on which is faster over the 40k time trial.
>
> > I think you'll find the seven seconds goes away very nicely. The aero
> > advantage on the bike with more slippery wheels will more than consume
> > the inertia disadvantage.

>
> (Excuse me):
> Send someone else on your errands, Frank.

No need. I see Carl has already done the work. Thanks, Carl.

> I already said that in a lot fewer words, and everybody already knows
> in the first place.

If that's the case, you've spent a lot of time and energy arguing to
no purpose. Drop the chip. Its inertia is slowing you.

- Frank Krygowski

dustoyevsky@mac.com

01-03-1970, 08:45 PM

On Nov 27, 7:30 pm, frkry...@gmail.com wrote:

>[apology] Accepted.

Phew. Was it close? Did you have to think about it?

> Ah. Yet, as I recall, this is not the first time you've laced into me
> for what I intended as a mild post. Sorry, but I simply don't believe
> you know the tone I intend better than I do.

Good one, Frank.

> No, just reduce my estimation of your judgment.

Oh my God, a new low for FK.

So what about the seven seconds you couldn't make go away, despite the
attempts to obfuscate via verbiage?

The "comparison" was a "standard" wheel, to give it a name, v. a
lighter one.

Let's get at the real problem here. A plain statement, please. --D-y

Jay Beattie

01-03-1970, 08:45 PM

On Nov 27, 6:40 pm, Ron Ruff <rruffrr...@yahoo.com> wrote:
> On Nov 26, 7:41 am, "dustoyev...@mac.com" <dustoyev...@mac.com> wrote:
>
> > In a crit, jumping out
> > of every corner (esp. in the V's <g>), "that would be more".
>
> I'm amazed at how often I see this. If you are in a crit and "jumping
> out of corners" then you are not in the race... and have much more
> important issues to address than getting lighter wheels. If you are
> near the front, you don't slow down for corners at all. If you need to
> *get* to the front then better aerodynamics is what you need since you
> will have your nose in the wind. If someone attacks then you need to
> accelerate to get on their wheel, but in nearly all circumstances
> better aerodynamics will help you there more than lower inertia.

What? I have placed in crits where, at some point, I was stuck in
traffic and had to jump out of a corner or two. With twisting crits
and circuit races, jumping out of corners is sometimes the only way
you can move up because the one straight spot turns in to a five
abreast drag strip. I don't know if a light wheel versus an aero
wheel makes any difference in this situation, though. Ultimately, to
win a sprint (or to move up in a wheel on wheel crit), you have to get
in to the wind. -- Jay Beattie.

carlfogel@comcast.net

01-03-1970, 08:45 PM

On Tue, 27 Nov 2007 18:47:55 -0800 (PST),
SocSecTrainWreck@earthlink.net wrote:

>On Nov 27, 3:34 pm, carlfo...@comcast.net wrote:
>> On Tue, 27 Nov 2007 03:23:05 -0800 (PST),
>> Sorry, but I got lost in the first sentence about mass starts somehow
>> favoring lighter wheels over aero wheels. They favor it for about the
>> length of time it takes the rider to get up to racing speed.
>
>You seem to be under a complete misconception about the nature of
>massed start racing. In those situations where you have a constant
>speed you are likely to be in someone's slipstream and going at a rate
>that is not necessarily that strenuous. Even in a break the ability to
>respond instantly to an attack will be more important than the
>advantage of aero wheels when you are pulling. On level ground if you
>lose contact with a break, your chances of getting back on thanks to
>your aero wheels are nil, but you might avoid the problem if you can
>respond quickly enough that you don't lose contact in the first place.
>And if the pace becomes serious in the peloton, you are constantly
>"getting up to racing speed". As I said before, your theoretical
>example is only found in the real world on the track.
>
>But to reiterate my earlier point: it's best to have light, aero rims.
>That's why people have carbon rims. They may be fashionable, expensive
>and less reliable, but they are also the fastest. Those who don't have
>them may want to rationalize their deficiency by saying the weight
>doesn't matter, but it does. Find another excuse, because there are
>better ones.

Dear Marten,

I think that the misconception is the notion that riders will somehow
be unable to accelerate enough to stay in the draft if their wheels
weigh 200 grams more.

The rider in front is trying to accelerate into the wind.

He's not likely to out-accelerate the rider sheltered behind him,
who's using 20%~30% less power to keep up.

If the pace becomes serious, the tiny accelerations involved in the
peloton are just that--tiny. You don't accelerate a bicycle and rider
at much more than a snail's pace from 25 mph, not matter how exciting
it may be to the riders.

As I've asked elsewhere, I wonder how much people think they're
accelerating in the last 200 yards. To be specific, they're almost
certainly going 25 mph or better as the pack gets within sight of the
finish line.

Then they accelerate in 600 feet to what, 40 mph? It's mostly the wind
drag that they're fighting, not spinning the tiny mass of the already
spinning wheels up a bit further.

As for carbon rims, they'd be lighter if they were less aero, but
they'd be slower.

Cheers,

Carl Fogel