University frame-flex testing: surprising results

[Thomas Hood]

http://materials.open.ac.uk/bikeframes/bikeframe.htm

Thomas Hood

[jim beam]

jobst.brandt@stanfordalumni.org wrote:
> Chalo Colina writes:
>
>>>> or was this all that was available in 19xx? Would you build a
>>>> bike your size of the now standard steel tubeset dimensions:
>>>> (34.9mm HT, 31.8mm DT, 28.6mR?m TT & ST)
>
>>> didn't have dished rear wheels back in those days, yet jobst's
>>> frame shimmys "at will". stupid to keep riding that when a better
>>> mechanical solution is only a few hundred dollars away.
>
>> For what it's worth...
>
>> The two bikes I've been putting the most miles on these days are
>> both built on old-fashioned 68cm lugged steel frames with 25.4mm top
>> tubes and 28.6mm down tubes. One of them (a '70s Nishiki) has a
>> clunky straight gauge tubeset, but the other (a pre-index '80s Fuji
>> Sagres) is double butted and respectably light. I haven't been able
>> to induce shimmy in either one of them, even zooming downhill at
>> automotive speeds. I think the lack of shimmy is probably more
>> attributable to the rigid and robust componentry (Primo Powerbite
>> BMX cranks, hefty steel-quilled stems, dishless 48 spoke wheels with
>> 700x40 tires) than to any characteristics of the frames.
>
>> As a point of comparison, the last bike I had that shimmied was
>> built on a massive straight gauge 68cm Cannondale touring frame with
>> a 2" downtube and oval seat stays-- probably the stiffest
>> commercially available road bike frame I have ever seen, let alone
>> ridden. That bike had much more flexible parts attached to it,
>> though (aluminum quill stem, drop bars, 36 spoke wheels with 126mm 7
>> speed rear, square taper crank).
>
>> So if Jobst's bike really does shimmy chronically, my guess is that
>> it has at least as much to do with the MA2 rims he uses as with the
>> diameters of tubing in his frame.
>
> I shimmies when I let it, while riding no-hands at around 23MPH and
> up. That the wheels are not the source was determined by filling the
> front tier completely with water, which made no difference,

filling tires with water doesn't affect wheel stiffness jobst, so of
course not!!!


> and
> changing the tire and tube onto a Rolf Vector Pro, and a Bontrager
> paired spoked wheel. None of these made any difference.

see above.


> When I
> reported this to Damon Rinard, he repeated the experiment at his lab
> with instrumentation that showed that shimmy buildup was the same and
> that frequency was identical. He used an accelerometer on the side of
> the headtube, the part of the bicycle that shimmies.

of course not. see above.


>
> http://www.sheldonbrown.com/brandt/shimmy.html

yet more drivel that needs correction. when jobst? when?

[Tom_A]

On Jan 16, 10:32 am, Thomas Hood <thomas.h...@gmail.com> wrote:
> http://materials.open.ac.uk/bikeframes/bikeframe.htm
>
> Thomas Hood

Hmmm...seems to me that they should have hung the weight offset from
the BB to create a moment about the BB rather than in line with the
axle centerline and better simulate actual loading...

[carlfogel@comcast.net]

On Wed, 16 Jan 2008 10:32:04 -0800 (PST), Thomas Hood
<thomas.hood@gmail.com> wrote:

>http://materials.open.ac.uk/bikeframes/bikeframe.htm
>
>Thomas Hood

Dear Thomas,

As usual, the measured flex was undetectable by any rider.

The flex in the no-fork column was from 1.47 mm to 2.46 mm, a range of
0.99 mm. At most, the flex was less than a tenth of an inch.

The flex in the with-fork column was from 1.30 mm to 1.99 mm, a range
of 0.69 mm. At most, the flex was just over a sixteenth of an inch.

Damon Rinard found similar results when he tested dozens of wheels:
http://www.sheldonbrown.com/rinard/wheel/index.htm

For steel spokes, practically all wheels that Rinard tested deflected
about 1~3 mm, depending on spoke count and whether they were front or
rear.

Wheels with struts or carbon fiber spokes usually deflected another
millimeter, but the enormous effort of testing all those wheels
basically showed that there was no significant difference.

Cheers,

Carl Fogel

[jobst.brandt@stanfordalumni.org]

Thomas Hood writes:

http://materials.open.ac.uk/bikeframes/bikeframe.htm

Looks like another "instrument it to death" project when there are
other approaches to define frame flex. Simple mechanical design
formulas exist for assessing bending and torsion in tubes, the problem
is deciding which forces one wants to analyze and which deflections
affect performance. Classically one sales gimmick was to stand next
to the bicycle and show how far the BB moves laterally when pushing
ones foot against it.

This test is eye catching but it is not what occurs when riding. I am
not sure what parameter is best to assess frame rigidity but for my
use, pedaling while standing is the mode in which I discovered where
most of the deflection occurred. It was the Cinelli quill stem. With
a threadless steertube and tubular bar stem, nearly all the flex
vanished. That is, my handlebars no loner seemed to be attached
elastically to the bicycle.

Another parameter I find interesting is the distance between front
axle and BB when braking hard. Much of that change occurs in the the
fork steertube and hardly any in bending the downtube. Rigidity in
this mode improves rider confidence in descending because front wheel
speed is consistent with the bicycle.

Before making a complicated test fixture and instrumentation, I think
analyzing which deflections are functional is most important to
identify. This of course assumes the frame is strong enough to not
fail in hard use. That is a more difficult characteristic to assess.

Jobst Brandt

[It's Chris]

Only thing I found suprising is how picky some cyclists can be. The
results on all the frames showed a deflrction of 1.3 and 2.7 mm. A total
varience of 1.4 millmeters (insert Ben Stein's "wow" here).

One thing I remember from high school science is that, within reason, a
spring is one of the most efficient means of storing kinetic energy, and
the subsequent release of that stored energy, with a minimum of loss.

1.4 millimeters sounds pretty reasonable to me.

- -
Compliments of:
"Your Friendly Neighborhood Wheelman"

If you want to E-mail me use:
ChrisZCorner "at" webtv "dot" net

My website:
http://geocities.com/czcorner

[M-gineering]

Tom_A wrote:
> On Jan 16, 10:32 am, Thomas Hood <thomas.h...@gmail.com> wrote:
>> http://materials.open.ac.uk/bikeframes/bikeframe.htm
>>
>> Thomas Hood
>
> Hmmm...seems to me that they should have hung the weight offset from
> the BB to create a moment about the BB rather than in line with the
> axle centerline and better simulate actual loading...

bolting the dropouts to the table creates a restraint which isn't realistic

--
/Marten

info(apestaartje)m-gineering(punt)nl

[Thomas Hood]

On 16 Jan, 19:32, carlfo...@comcast.net wrote:
> On Wed, 16 Jan 2008 10:32:04 -0800 (PST), Thomas Hood
>
> <thomas.h...@gmail.com> wrote:
> >http://materials.open.ac.uk/bikeframes/bikeframe.htm
>
> >Thomas Hood
>
> Dear Thomas,
>
> As usual, the measured flex was undetectable by any rider.
>
> The flex in the no-fork column was from 1.47 mm to 2.46 mm, a range of
> 0.99 mm. At most, the flex was less than a tenth of an inch.
>
> The flex in the with-fork column was from 1.30 mm to 1.99 mm, a range
> of 0.69 mm. At most, the flex was just over a sixteenth of an inch.
>
> Damon Rinard found similar results when he tested dozens of wheels:
> http://www.sheldonbrown.com/rinard/wheel/index.htm
>
> For steel spokes, practically all wheels that Rinard tested deflected
> about 1~3 mm, depending on spoke count and whether they were front or
> rear.
>
> Wheels with struts or carbon fiber spokes usually deflected another
> millimeter, but the enormous effort of testing all those wheels
> basically showed that there was no significant difference.
>
> Cheers,
>
> Carl Fogel

Carl,

You're preaching to the choir... It was the relative placings I found
surprising, particularly the Alan/ GT.

Regards,

Thomas Hood

[John Forrest Tomlinson]

On Wed, 16 Jan 2008 12:32:51 -0700, carlfogel@comcast.net wrote:

>On Wed, 16 Jan 2008 10:32:04 -0800 (PST), Thomas Hood
><thomas.hood@gmail.com> wrote:
>
>>http://materials.open.ac.uk/bikeframes/bikeframe.htm
>>
>>Thomas Hood
>
>Dear Thomas,
>
>As usual, the measured flex was undetectable by any rider.

I'm having trouble finding where it says this.

[Thomas Hood]

On 16 Jan, 19:38, jobst.bra...@stanfordalumni.org wrote:
> This test is eye catching but it is not what occurs when riding. I am
> not sure what parameter is best to assess frame rigidity but for my
> use, pedaling while standing is the mode in which I discovered where
> most of the deflection occurred. It was the Cinelli quill stem. With
> a threadless steertube and tubular bar stem, nearly all the flex
> vanished. That is, my handlebars no loner seemed to be attached
> elastically to the bicycle.

As you've stated previously, the handlebars on your bike are narrow
steel Cinelli items from the 60's. In this respect your bike is
different to 99% of those in this group. How thick are the walls on
this bar, and how wide is it, as I'm interested in whether this bar is
dramatically stiffer than an alloy bar. The bar on my bicycle is a
relatively hefty 42cm 300 g plain-gauge (1.7mm) 3T sleeved (0.7mm)
item, and I can certainly feel the bar twist between the brake hoods
when standing.

If you had to purchase a handlebar now, you would not be able to
purchase a steel handlebar. Given this constraint, is the 31.8 mm
oversize standard ( http://tinyurl.com/28a8up ) better from a
durability point of view?


>
> Another parameter I find interesting is the distance between front
> axle and BB when braking hard. Much of that change occurs in the the
> fork steertube and hardly any in bending the downtube. Rigidity in
> this mode improves rider confidence in descending because front wheel
> speed is consistent with the bicycle.

Again, here your bike is atypical being so large. From pictures of
your bike it appears that the distance between the head bearings is
~3/4 of the length of you forks (on my bike it is ~ 1/3)

If your frame and forks are built from materials similar to these is
the flex really mainly in the steertube rather than in the blades?
http://www.reynoldscycles.co.uk/downloads/PARTLIST.pdf (see page 4)

Assuming a 2.1mm steertube and oval 0.9mm blades of 27.5 x 20 can
anyone approximate the bending stiffness of the blades vs. the
steertube?
(I'm not being idle, but I couldn't find a the formula for 'bending
stiffness of a tube' despite Googling...)

Would a 1-1/8" steertube not have been a better choice on your bike,
or was this all that was available in 19xx ? Would you build a bike
your size of the now standard steel tubeset dimensions: (34.9mm HT,
31.8mm DT, 28.6mm TT & ST)

Thanks,

Thomas Hood

[bicycle_disciple]

On Jan 16, 2:08*pm, M-gineering <ikmotgeens...@m-gineering.nl> wrote:
> Tom_A wrote:
> > On Jan 16, 10:32 am, Thomas *Hood <thomas.h...@gmail.com> wrote:
> >>http://materials.open.ac.uk/bikeframes/bikeframe.htm
>
> >> Thomas Hood
>
> > Hmmm...seems to me that they should have hung the weight offset from
> > the BB to create a moment about the BB rather than in line with the
> > axle centerline and better simulate actual loading...
>
> bolting the dropouts to the table creates a restraint which isn't realistic
>
> --
> /Marten
>
> info(apestaartje)m-gineering(punt)nl

The German Fatigue test agency have been doing this for sometime.
Cannondales frequently top the list of stiffest frames. True,
deflections are so small to characterize but the industry is making a
big issue out of it. Its a clear selling point.

B.D

http://cozybeehive.blogspot.com

[Luke]

In article
<3e866690-2c5e-43f5-bd0b-1608f94dea94@s13g2000prd.googlegroups.com>,
bicycle_disciple <1.crazyboy.only@gmail.com> wrote:

> On Jan 16, 2:08*pm, M-gineering <ikmotgeens...@m-gineering.nl> wrote:
> > Tom_A wrote:
> > > On Jan 16, 10:32 am, Thomas *Hood <thomas.h...@gmail.com> wrote:
> > >>http://materials.open.ac.uk/bikeframes/bikeframe.htm
> >
> > >> Thomas Hood
> >
> > > Hmmm...seems to me that they should have hung the weight offset from
> > > the BB to create a moment about the BB rather than in line with the
> > > axle centerline and better simulate actual loading...
> >
> > bolting the dropouts to the table creates a restraint which isn't realistic
> >

Help me to understand why the degree of BB deflection decreases when
the test frames have forks installed. I should think the opposite would
be the case with the forks adding their own degree of flex to that of
the frame.

Unfortunately the testers' photos and description do not reveal how the
forkless frames were secured to the testing jig; could the fastening
method be skewing the results?

[jobst.brandt@stanfordalumni.org]

Thomas Hood writes:

>> This test is eye catching but it is not what occurs when riding. I
>> am not sure what parameter is best to assess frame rigidity but for
>> my use, pedaling while standing is the mode in which I discovered
>> where most of the deflection occurred. It was the Cinelli quill
>> stem. With a threadless steertube and tubular bar stem, nearly all
>> the flex vanished. That is, my handlebars no loner seemed to be
>> attached elastically to the bicycle.

> As you've stated previously, the handlebars on your bike are narrow
> steel Cinelli items from the 60's. In this respect your bike is
> different to 99% of those in this group. How thick are the walls on
> this bar, and how wide is it, as I'm interested in whether this bar
> is dramatically stiffer than an alloy bar. The bar on my bicycle is
> a relatively hefty 42cm 300 g plain-gauge (1.7mm) 3T sleeved (0.7mm)
> item, and I can certainly feel the bar twist between the brake hoods
> when standing.

> If you had to purchase a handlebar now, you would not be able to
> purchase a steel handlebar. Given this constraint, is the 31.8 mm
> oversize standard ( http://tinyurl.com/28a8up ) better from a
> durability point of view?

That's not germane, the pint is that I achieved a great improvement in
rigidity, one that was entirely the quill stem replacement. If I had
ridden with wider bars, the effect would probably been greater. I
found this improvement especially good because I undertook it to get
rid of frozen stems in the steertube, something that occurred even
though there was an O-ring seal on the head bearing lock nut.

>> Another parameter I find interesting is the distance between front
>> axle and BB when braking hard. Much of that change occurs in the
>> the fork steertube and hardly any in bending the downtube.
>> Rigidity in this mode improves rider confidence in descending
>> because front wheel speed is consistent with the bicycle.

> Again, here your bike is atypical being so large. From pictures of
> your bike it appears that the distance between the head bearings is
> ~3/4 of the length of you forks (on my bike it is ~ 1/3)

> If your frame and forks are built from materials similar to these is
> the flex really mainly in the steertube rather than in the blades?

http://www.reynoldscycles.co.uk/downloads/PARTLIST.pdf (see page 4)

Probably, considering the fork blade fore and aft width compared to
the steer tube. The point is that you can rock a bicycle fore and aft
with the front brake clamped and watch that motion. Viscount bicycles
were miserable at that, and I never saw a tall frame of these.

> Assuming a 2.1mm steertube and oval 0.9mm blades of 27.5 x 20 can
> anyone approximate the bending stiffness of the blades vs. the
> steertube?

> (I'm not being idle, but I couldn't find a the formula for 'bending
> stiffness of a tube' despite Googling...)

Timoshenko has all those formulas in profusion, however for rectangular
cross sections the bending stiffness goes as the third power of the
bending height and I'm sure that oval cross sections are somewhere in
between the second and third power depending on shape.

> Would a 1-1/8" steertube not have been a better choice on your bike,
> or was this all that was available in 19xx ? Would you build a bike
> your size of the now standard steel tubeset dimensions: (34.9mm HT,
> 31.8mm DT, 28.6mm TT & ST)

I don't need not steenkin fat tube. Mine works well enough as I brake
hard enough to raise the rear wheel on my long wheelbase bicycle.

Jobst Brandt

[russellseaton1@yahoo.com]

On Jan 17, 3:25*pm, Thomas Hood <thomas.h...@gmail.com> wrote:
> On 16 Jan, 19:38, jobst.bra...@stanfordalumni.org wrote:
>
> > This test is eye catching but it is not what occurs when riding. *I am
> > not sure what parameter is best to assess frame rigidity but for my
> > use, pedaling while standing is the mode in which I discovered where
> > most of the deflection occurred. *It was the Cinelli quill stem. *With
> > a threadless steertube and tubular bar stem, nearly all the flex
> > vanished. *That is, my handlebars no loner seemed to be attached
> > elastically to the bicycle.
>
> As you've stated previously, the handlebars on your bike are narrow
> steel Cinelli items from the 60's. In this respect your bike is
> different to 99% of those in this group. How thick are the walls on
> this bar, and how wide is it, as I'm interested in whether this bar is
> dramatically stiffer than an alloy bar. The bar on my bicycle is a
> relatively hefty 42cm 300 g plain-gauge (1.7mm) 3T sleeved (0.7mm)
> item, and I can certainly feel the bar twist between the brake hoods
> when standing.
>
> If you had to purchase a handlebar now, you would not be able to
> purchase a steel handlebar.

http://www.yellowjersey.org/nitto.html





Given this constraint, is the 31.8 mm
> oversize standard (http://tinyurl.com/28a8up) better from a
> durability point of view?
>
>
>
> > Another parameter I find interesting is the distance between front
> > axle and BB when braking hard. *Much of that change occurs in the the
> > fork steertube and hardly any in bending the downtube. *Rigidity in
> > this mode improves rider confidence in descending because front wheel
> > speed is consistent with the bicycle.
>
> Again, here your bike is atypical being so large. From pictures of
> your bike it appears that the distance between the head bearings is
> ~3/4 of the length of you forks (on my bike it is ~ 1/3)
>
> If your frame and forks are built from materials similar to these is
> the flex really mainly in the steertube rather than in the blades?http://www.reynoldscycles.co.uk/downloads/PARTLIST.pdf(see page 4)
>
> Assuming a 2.1mm steertube and oval 0.9mm blades of 27.5 x 20 can
> anyone approximate the bending stiffness of the blades vs. the
> steertube?
> (I'm not being idle, but I couldn't find a the formula for 'bending
> stiffness of a tube' despite Googling...)
>
> Would a 1-1/8" steertube not have been a better choice on your bike,
> or was this all that was available in 19xx ? *Would you build a bike
> your size of the now standard steel tubeset dimensions: (34.9mm HT,
> 31.8mm DT, 28.6mm TT & ST)
>
> Thanks,
>
> Thomas Hood

[A Muzi]

-snip-
Thomas Hood wrote:
> If you had to purchase a handlebar now, you would not be able to
> purchase a steel handlebar.
-snip-

Why is that?
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

[jim beam]

Thomas Hood wrote:
> On 16 Jan, 19:38, jobst.bra...@stanfordalumni.org wrote:
>> This test is eye catching but it is not what occurs when riding. I am
>> not sure what parameter is best to assess frame rigidity but for my
>> use, pedaling while standing is the mode in which I discovered where
>> most of the deflection occurred. It was the Cinelli quill stem. With
>> a threadless steertube and tubular bar stem, nearly all the flex
>> vanished. That is, my handlebars no loner seemed to be attached
>> elastically to the bicycle.
>
> As you've stated previously, the handlebars on your bike are narrow
> steel Cinelli items from the 60's. In this respect your bike is
> different to 99% of those in this group. How thick are the walls on
> this bar, and how wide is it, as I'm interested in whether this bar is
> dramatically stiffer than an alloy bar. The bar on my bicycle is a
> relatively hefty 42cm 300 g plain-gauge (1.7mm) 3T sleeved (0.7mm)
> item, and I can certainly feel the bar twist between the brake hoods
> when standing.
>
> If you had to purchase a handlebar now, you would not be able to
> purchase a steel handlebar. Given this constraint, is the 31.8 mm
> oversize standard ( http://tinyurl.com/28a8up ) better from a
> durability point of view?

for the same wall thickness, of course.


>
>
>> Another parameter I find interesting is the distance between front
>> axle and BB when braking hard. Much of that change occurs in the the
>> fork steertube and hardly any in bending the downtube. Rigidity in
>> this mode improves rider confidence in descending because front wheel
>> speed is consistent with the bicycle.
>
> Again, here your bike is atypical being so large. From pictures of
> your bike it appears that the distance between the head bearings is
> ~3/4 of the length of you forks (on my bike it is ~ 1/3)
>
> If your frame and forks are built from materials similar to these is
> the flex really mainly in the steertube rather than in the blades?
> http://www.reynoldscycles.co.uk/downloads/PARTLIST.pdf (see page 4)
>
> Assuming a 2.1mm steertube and oval 0.9mm blades of 27.5 x 20 can
> anyone approximate the bending stiffness of the blades vs. the
> steertube?
> (I'm not being idle, but I couldn't find a the formula for 'bending
> stiffness of a tube' despite Googling...)
>
> Would a 1-1/8" steertube not have been a better choice on your bike,

of course. oversize tube is absolutely the way to go. it helps with
fatigue and it helps with stiffness, [and therefore shimmy] - good for
bikes with dished rear wheels.


> or was this all that was available in 19xx ? Would you build a bike
> your size of the now standard steel tubeset dimensions: (34.9mm HT,
> 31.8mm DT, 28.6mm TT & ST)


didn't have dished rear wheels back in those days, yet jobst's frame
shimmys "at will". stupid to keep riding that when a better mechanical
solution is only a few hundred dollars away.

[jim beam]

jobst.brandt@stanfordalumni.org wrote:
<snip irrelevance>

>
> I don't need not steenkin fat tube. Mine works well enough as I brake
> hard enough to raise the rear wheel on my long wheelbase bicycle.

wow, frame tube stiffness affects braking on your single pivot
calipers??? spectacular jobst!!! absolutely freakin' spectacular.

[Thomas Hood]

On 17 Jan, 22:33, jobst.bra...@stanfordalumni.org wrote:
> Thomas Hood writes:
> > If you had to purchase a handlebar now, you would not be able to
> > purchase a steel handlebar. Given this constraint, is the 31.8 mm
> > oversize standard (http://tinyurl.com/28a8up) better from a
> > durability point of view?
>
> That's not germane, the pint is that I achieved a great improvement in
> rigidity, one that was entirely the quill stem replacement.

I understand the point about the stem, I was just using it as a segway
to a question about handlebars. My question still stands.

> >> Another parameter I find interesting is the distance between front
> >> axle and BB when braking hard. Much of that change occurs in the
> >> the fork steertube and hardly any in bending the downtube.
> >> Rigidity in this mode improves rider confidence in descending
> >> because front wheel speed is consistent with the bicycle.
<snip>
> > Would a 1-1/8" steertube not have been a better choice on your bike,
> > or was this all that was available in 19xx ? Would you build a bike
> > your size of the now standard steel tubeset dimensions: (34.9mm HT,
> > 31.8mm DT, 28.6mm TT & ST)
>
> I don't need not steenkin fat tube. Mine works well enough as I brake
> hard enough to raise the rear wheel on my long wheelbase bicycle.
>
To paraphrase, you stated: 'rigidity in the steertube improves rider
confidence decending.'

So, assuming a choice between the two (weighing the same) would you
still prefer a 1" steertube?

Both these questions relate to the fact that 1" handlebars/stems and
steerers/heasets are becoming increasingly rare. You have often stated
a preference for 1" steerers and tacitly 1" handlebars.

Are their disadvantages to 1-1/8" steerers and handlebars you haven't
mentioned? It seems perverse to favour 1" otherwise.

Thanks,

Thomas Hood

[Thomas Hood]

On 17 Jan, 23:29, "russellseat...@yahoo.com"
<russellseat...@yahoo.com> wrote:
> > If you had to purchase a handlebar now, you would not be able to
> > purchase a steel handlebar.
>
> http://www.yellowjersey.org/nitto.html
>

If you had arms like an ape, perhaps, but these aren't much use to
your average road cyclist :-)

Tom

[carlfogel@comcast.net]

On Thu, 17 Jan 2008 18:40:44 -0500, John Forrest Tomlinson
<usenetremove@jt10000.com> wrote:

>On Wed, 16 Jan 2008 12:32:51 -0700, carlfogel@comcast.net wrote:
>
>>On Wed, 16 Jan 2008 10:32:04 -0800 (PST), Thomas Hood
>><thomas.hood@gmail.com> wrote:
>>
>>>http://materials.open.ac.uk/bikeframes/bikeframe.htm
>>>
>>>Thomas Hood
>>
>>Dear Thomas,
>>
>>As usual, the measured flex was undetectable by any rider.
>
>I'm having trouble finding where it says this.

Dear John,

That's because I said that the measured flex was undetectable by any
rider, not the report.

The maximum measured flex amounted to less than a tenth of an inch.

As Damon Rinard's tests show, the same load will deflect the rims of
each of a rider's wire-spoked wheels roughly as much.

In actual cornering, the rubber tires will deform even more.

No rider can detect a frame smoothly flexing less than a tenth of an
inch at the bottom bracket amidst all the other things happening
during cornering.

The road surface is likely to vary considerably more than a tenth of
an inch. The rider's shoes and socks are likely to squash more than a
tenth of an inch.

The rider cannot steer to within a tenth of an inch through corner.

This does not, however, stop bicyclists from believing that they can
sense all sorts of infinitesimal differences.

Cheers,

Carl Fogel

[Tom Sherman]

Andrew Muzi wrote:
> -snip-
> Thomas Hood wrote:
>> If you had to purchase a handlebar now, you would not be able to
>> purchase a steel handlebar.
> -snip-
>
> Why is that?
>
Palo Alto is a special ferrous handlebar free zone, with existing
handlebars "grandfathered" in. ;)

--
Tom Sherman - Holstein-Friesland Bovinia
"And never forget, life ultimately makes failures of all people."
- A. Derleth

[Chalo]

jim beam wrote:
>
> > or was this all that was available in 19xx ? Would you build a bike
> > your size of the now standard steel tubeset dimensions: (34.9mm HT,
> > 31.8mm DT, 28.6mm TT & ST)
>
> didn't have dished rear wheels back in those days, yet jobst's frame
> shimmys "at will". stupid to keep riding that when a better mechanical
> solution is only a few hundred dollars away.

For what it's worth...

The two bikes I've been putting the most miles on these days are both
built on old-fashioned 68cm lugged steel frames with 25.4mm top tubes
and 28.6mm down tubes. One of them (a '70s Nishiki) has a clunky
straight gauge tubeset, but the other (a pre-index '80s Fuji Sagres)
is double butted and respectably light. I haven't been able to induce
shimmy in either one of them, even zooming downhill at automotive
speeds. I think the lack of shimmy is probably more attributable to
the rigid and robust componentry (Primo Powerbite BMX cranks, hefty
steel-quilled stems, dishless 48 spoke wheels with 700x40 tires) than
to any characteristics of the frames.

As a point of comparison, the last bike I had that shimmied was built
on a massive straight gauge 68cm Cannondale touring frame with a 2"
downtube and oval seat stays-- probably the stiffest commercially
available road bike frame I have ever seen, let alone ridden. That
bike had much more flexible parts attached to it, though (aluminum
quill stem, drop bars, 36 spoke wheels with 126mm 7 speed rear, square
taper crank).

So if Jobst's bike really does shimmy chronically, my guess is that it
has at least as much to do with the MA2 rims he uses as with the
diameters of tubing in his frame.

Chalo

[John Forrest Tomlinson]

On Thu, 17 Jan 2008 21:36:51 -0700, carlfogel@comcast.net wrote:

>On Thu, 17 Jan 2008 18:40:44 -0500, John Forrest Tomlinson
><usenetremove@jt10000.com> wrote:
>
>>On Wed, 16 Jan 2008 12:32:51 -0700, carlfogel@comcast.net wrote:
>>
>>>On Wed, 16 Jan 2008 10:32:04 -0800 (PST), Thomas Hood
>>><thomas.hood@gmail.com> wrote:
>>>
>>>>http://materials.open.ac.uk/bikeframes/bikeframe.htm
>>>>
>>>>Thomas Hood
>>>
>>>Dear Thomas,
>>>
>>>As usual, the measured flex was undetectable by any rider.
>>
>>I'm having trouble finding where it says this.
>
>Dear John,
>
>That's because I said that the measured flex was undetectable by any
>rider, not the report.

I see, the way you wrote earler sounded like they tested rider
perceptions.

[Chalo]

Carl Fogel wrote:
>
> The maximum measured flex amounted to less than a tenth of an inch.
<snip>
> This does not, however, stop bicyclists from believing that they can
> sense all sorts of infinitesimal differences.

Dimensionally, that is surely an infinitesimal difference. I wonder,
however, what is the force normal to the deflection at the frame? I
assume that some portion of the work represented by the displacement
times the average force required to effect that displacement is
unrecoverable.

Let's say that half the energy stored as frame springing can be
recovered as drive energy to the rear wheel, and half can't be
recovered. (The real percentage would be wildly variable and highly
dependent on pedaling style.) And, just to use round figures, let's
say that the stiffest frame deflects 1mm with a normal force of 1000N,
and the springiest one deflects 3mm with the same force, yielding a
difference in deflection of 2mm.

1000 newtons times 1/1000 meter equals 1 joule. Since the stored work
is actually the product of the distance of displacement times the
force as it increases linearly from zero to 1000N, then the average
force through that distance would be 500N, and the stored work would
be 0.5 joule. That's the amount of work stored in the springing of
the stiffer bike's frame. So if half of that is recoverable, then
0.25 joule is lost to each mighty pedal stroke of such magnitude when
riding the stiffer bike.

For the springier bike frame, all the values are equal except
displacement. So the stored work is 500N times 3mm, or 1.5 joule. a
loss of half that amount would be 0.75 joule, for a loss difference of
0.5 joule per mighty pedal stroke.

If we guess that the effective average force of the pedal stroke is
approximately the same 500N on average, and the effective displacement
of that stroke is 250mm, then the total work from which our frame-
springing losses are to be deducted is 125 joules. 0.5 joule divided
by 125 joules equals a proportional loss of 0.4%.

I admit that this analysis contains a purely conjectural assumption
about how much of the energy stored as frame springing is recoverable,
as well as the assumption that this value isn't highly dependent on
the absolute amount of displacement. So, it's basically worth the
paper it's written on. But even though an efficiency difference of
one-quarter to one-half of a percent would be almost impossible to
measure except by statistical means, and even though it would be a
poor bargain for a recreational or transportational rider if it
exacted a noticeable penalty in comfort, it seems obvious that
competitive riders should pursue a potential advantage of such size
wherever one is offered.

I wonder what the difference is in stiffness among the frames that can
be found in the professional peloton, and whether statistical analysis
of a large number of race results and a large number of riders would
uncover any categorical advantage for stiffer frames.

Chalo

[jim beam]

Chalo wrote:
> jim beam wrote:
>>> or was this all that was available in 19xx ? Would you build a bike
>>> your size of the now standard steel tubeset dimensions: (34.9mm HT,
>>> 31.8mm DT, 28.6mm TT & ST)
>> didn't have dished rear wheels back in those days, yet jobst's frame
>> shimmys "at will". stupid to keep riding that when a better mechanical
>> solution is only a few hundred dollars away.
>
> For what it's worth...
>
> The two bikes I've been putting the most miles on these days are both
> built on old-fashioned 68cm lugged steel frames with 25.4mm top tubes
> and 28.6mm down tubes. One of them (a '70s Nishiki) has a clunky
> straight gauge tubeset, but the other (a pre-index '80s Fuji Sagres)
> is double butted and respectably light. I haven't been able to induce
> shimmy in either one of them, even zooming downhill at automotive
> speeds. I think the lack of shimmy is probably more attributable to
> the rigid and robust componentry (Primo Powerbite BMX cranks, hefty
> steel-quilled stems, dishless 48 spoke wheels with 700x40 tires) than
> to any characteristics of the frames.
>
> As a point of comparison, the last bike I had that shimmied was built
> on a massive straight gauge 68cm Cannondale touring frame with a 2"
> downtube and oval seat stays-- probably the stiffest commercially
> available road bike frame I have ever seen, let alone ridden. That
> bike had much more flexible parts attached to it, though (aluminum
> quill stem, drop bars, 36 spoke wheels with 126mm 7 speed rear, square
> taper crank).
>
> So if Jobst's bike really does shimmy chronically, my guess is that it
> has at least as much to do with the MA2 rims he uses as with the
> diameters of tubing in his frame.
>

the two factors, wheels and frame, work together. wheels that will
shimmy on a flexible frame, won't on a stiff one. flexible wheels on a
shimmy frame make it shimmy bad. stiff wheels on a shimmy frame make
shimmy much harder to induce.

[jobst.brandt@stanfordalumni.org]

Chalo Colina writes:

>>> or was this all that was available in 19xx? Would you build a
>>> bike your size of the now standard steel tubeset dimensions:
>>> (34.9mm HT, 31.8mm DT, 28.6mR?m TT & ST)

>> didn't have dished rear wheels back in those days, yet jobst's
>> frame shimmys "at will". stupid to keep riding that when a better
>> mechanical solution is only a few hundred dollars away.

> For what it's worth...

> The two bikes I've been putting the most miles on these days are
> both built on old-fashioned 68cm lugged steel frames with 25.4mm top
> tubes and 28.6mm down tubes. One of them (a '70s Nishiki) has a
> clunky straight gauge tubeset, but the other (a pre-index '80s Fuji
> Sagres) is double butted and respectably light. I haven't been able
> to induce shimmy in either one of them, even zooming downhill at
> automotive speeds. I think the lack of shimmy is probably more
> attributable to the rigid and robust componentry (Primo Powerbite
> BMX cranks, hefty steel-quilled stems, dishless 48 spoke wheels with
> 700x40 tires) than to any characteristics of the frames.

> As a point of comparison, the last bike I had that shimmied was
> built on a massive straight gauge 68cm Cannondale touring frame with
> a 2" downtube and oval seat stays-- probably the stiffest
> commercially available road bike frame I have ever seen, let alone
> ridden. That bike had much more flexible parts attached to it,
> though (aluminum quill stem, drop bars, 36 spoke wheels with 126mm 7
> speed rear, square taper crank).

> So if Jobst's bike really does shimmy chronically, my guess is that
> it has at least as much to do with the MA2 rims he uses as with the
> diameters of tubing in his frame.

It shimmies when I let it, while riding no-hands at around 23MPH and
up. That the wheels are not the source was determined by filling the
front tire completely with water, which made no difference, and
changing the tire and tube onto a Rolf Vector Pro, and a Bontrager
paired spoked wheel. None of these made any difference. When I
reported this to Damon Rinard, he repeated the experiment at his lab
with instrumentation that showed that shimmy buildup was the same and
that frequency was identical. He used an accelerometer on the side of
the headtube, the part of the bicycle that shimmies.

http://www.sheldonbrown.com/brandt/shimmy.html

Jobst Brandt

[Tom Sherman]

"jim beam" wrote:
> ...
> filling tires with water doesn't affect wheel stiffness jobst, so of
> course not!!!...
>
If it is cold enough, the water will affect wheel stiffness!

--
Tom Sherman - Holstein-Friesland Bovinia
"And never forget, life ultimately makes failures of all people."
- A. Derleth

[Chalo]

Tom Sherman wrote:
>
> jim beam wrote:
> > ...
> > filling tires with water doesn't affect wheel stiffness jobst, so of
> > course not!!!...
>
> If it is cold enough, the water will affect wheel stiffness!

You mean as cold as "Holstein-Freezeland Bovinia"?

Chalo

[Tom Sherman]

Chalo Colina wrote:
> Tom Sherman wrote:
>> jim beam wrote:
>>> ...
>>> filling tires with water doesn't affect wheel stiffness jobst, so of
>>> course not!!!...
>> If it is cold enough, the water will affect wheel stiffness!
>
> You mean as cold as "Holstein-Freezeland Bovinia"?
>
Well, the water would not stay in a liquid form for long around here
right now.

--
Tom Sherman - Holstein-Friesland Bovinia
"And never forget, life ultimately makes failures of all people."
- A. Derleth

[M-gineering]

It's Chris wrote:
> Only thing I found suprising is how picky some cyclists can be. The
> results on all the frames showed a deflrction of 1.3 and 2.7 mm. A total
> varience of 1.4 millmeters (insert Ben Stein's "wow" here).
>


I think you need some coffee. Those figures show that the one frame was
more than two times as stiff as the other!


--
/Marten (never could make much from sidestiffness, torsional stiffness
is where it's at imho)

info(apestaartje)m-gineering(punt)nl

[Tom Sherman]

Thomas Hood wrote:
> On 17 Jan, 23:29, "russellseat...@yahoo.com"
> <russellseat...@yahoo.com> wrote:
>>> If you had to purchase a handlebar now, you would not be able to
>>> purchase a steel handlebar.
>> http://www.yellowjersey.org/nitto.html
>>
>
> If you had arms like an ape, perhaps, but these aren't much use to
> your average road cyclist :-)
>
Except for the odd circus bear, all cyclists ARE apes.

--
Tom Sherman - Holstein-Friesland Bovinia
"And never forget, life ultimately makes failures of all people."
- A. Derleth

[Sandy]

Dans le message de
news:18562e37-5236-4800-9bcc-355e3b2a2ecf@d21g2000prf.googlegroups.com,
Thomas Hood <thomas.hood@gmail.com> a réfléchi, et puis a déclaré :
> On 17 Jan, 22:33, jobst.bra...@stanfordalumni.org wrote:
>> Thomas Hood writes:
>>> If you had to purchase a handlebar now, you would not be able to
>>> purchase a steel handlebar. Given this constraint, is the 31.8 mm
>>> oversize standard (http://tinyurl.com/28a8up) better from a
>>> durability point of view?
>>
>> That's not germane, the pint is that I achieved a great improvement
>> in rigidity, one that was entirely the quill stem replacement.
>
> I understand the point about the stem, I was just using it as a segway
> to a question about handlebars. My question still stands.
>
>>>> Another parameter I find interesting is the distance between front
>>>> axle and BB when braking hard. Much of that change occurs in the
>>>> the fork steertube and hardly any in bending the downtube.
>>>> Rigidity in this mode improves rider confidence in descending
>>>> because front wheel speed is consistent with the bicycle.
> <snip>
>>> Would a 1-1/8" steertube not have been a better choice on your bike,
>>> or was this all that was available in 19xx ? Would you build a bike
>>> your size of the now standard steel tubeset dimensions: (34.9mm HT,
>>> 31.8mm DT, 28.6mm TT & ST)
>>
>> I don't need not steenkin fat tube. Mine works well enough as I
>> brake hard enough to raise the rear wheel on my long wheelbase
>> bicycle.
>>
> To paraphrase, you stated: 'rigidity in the steertube improves rider
> confidence decending.'
>
> So, assuming a choice between the two (weighing the same) would you
> still prefer a 1" steertube?
>
> Both these questions relate to the fact that 1" handlebars/stems and
> steerers/heasets are becoming increasingly rare. You have often stated
> a preference for 1" steerers and tacitly 1" handlebars.
>
> Are their disadvantages to 1-1/8" steerers and handlebars you haven't
> mentioned? It seems perverse to favour 1" otherwise.
>
> Thanks,
>
> Thomas Hood

I presume you have found headtubes of 1" that accommodate fork shafts of 1
1/8". I wonder what sort of headset capably supports this arrangement.

On the other hand, headset reducers exist for 1 1/8" headtubes to hold 1"
fork shafts, but I don't think they are thought of as especially stable.

Where did I miss your point?
--
Bonne route !

Sandy
Verneuil-sur-Seine FR

[jobst.brandt@stanfordalumni.org]

Thomas Hood writes:

>>> If you had to purchase a handlebar now, you would not be able to
>>> purchase a steel handlebar. Given this constraint, is the 31.8 mm
>>> oversize standard :

http://tinyurl.com/28a8up

>>> better from a durability point of view?

>> That's not germane, the point is that I achieved a great
>> improvement in rigidity, one that was entirely the quill stem
>> replacement.

> I understand the point about the stem, I was just using it as a
> Segway to a question about handlebars. My question still stands.

So what is not durable about my steertube? If there were a problem I
would be interested, but I don't get frozen quill stem syndrome any
longer and I don't need the stupid long head adjustment wrenches any
more. Since switching to swiveling head bearings (Shimano) I haven't
had dimples in the races (indexed steering) from fretting damage.

>>>> Another parameter I find interesting is the distance between
>>>> front axle and BB when braking hard. Much of that change occurs
>>>> in the the fork steertube and hardly any in bending the downtube.
>>>> Rigidity in this mode improves rider confidence in descending
>>>> because front wheel speed is consistent with the bicycle.

>>> Would a 1-1/8" steertube not have been a better choice on your
>>> bike, or was this all that was available in 19xx ? Would you
>>> build a bike your size of the now standard steel tubeset
>>> dimensions: (34.9mm HT, 31.8mm DT, 28.6mm TT & ST)

>> I don't need not steenkin fat tube. Mine works well enough as I
>> brake hard enough to raise the rear wheel on my long wheelbase
>> bicycle.

> To paraphrase, you stated: 'rigidity in the steertube improves rider
> confidence descending.'

I don't have any complaints in that consideration, but I see riders
that do. The same goes for shimmy. It doesn't do that unless I make
a point of letting it do so while riding no-hands at higher speed.

> So, assuming a choice between the two (weighing the same) would you
> still prefer a 1" steertube?

I would have to try a similar bicycle to see if anything changed to my
benefit before switching. If these head bearings were no longer made,
I would prefer to switch.

> Both these questions relate to the fact that 1" handlebars/stems and
> steerers/heasets are becoming increasingly rare. You have often
> stated a preference for 1" steerers and tacitly 1" handlebars.

Bars last a long time and are not a wear item as bar tape is. I think
my head bearings will last a long time as well.

> Are their disadvantages to 1-1/8" steerers and handlebars you
> haven't mentioned? It seems perverse to favour 1" otherwise.

That is not what I said. I don't gratuitously get a new bicycle to
keep up with fashion. That is why I prefer to stay with the equipment
I have unless I can see advantage in changing.

Jobst Brandt

[Bill Sornson]

Thomas Hood wrote:

> I understand the point about the stem, I was just using it as a segway
> to a question about handlebars.
> ^^^^^^^

Too lazy to walk?

[Michael Press]

In article
<18562e37-5236-4800-9bcc-355e3b2a2ecf@d21g2000prf.googlegroups.com>,
Thomas Hood <thomas.hood@gmail.com> wrote:

> On 17 Jan, 22:33, jobst.bra...@stanfordalumni.org wrote:
> > Thomas Hood writes:
> > > If you had to purchase a handlebar now, you would not be able to
> > > purchase a steel handlebar. Given this constraint, is the 31.8 mm
> > > oversize standard (http://tinyurl.com/28a8up) better from a
> > > durability point of view?
> >
> > That's not germane, the pint is that I achieved a great improvement in
> > rigidity, one that was entirely the quill stem replacement.
>
> I understand the point about the stem, I was just using it as a segway
^^^^^^
segue

--
Michael Press

[Tim McNamara]

In article <fmqi1p$hne$1@localhost.localdomain>,
M-gineering <ikmotgeenspam@m-gineering.nl> wrote:

> It's Chris wrote:
> > Only thing I found suprising is how picky some cyclists can be. The
> > results on all the frames showed a deflrction of 1.3 and 2.7 mm. A
> > total varience of 1.4 millmeters (insert Ben Stein's "wow" here).
>
> I think you need some coffee. Those figures show that the one frame
> was more than two times as stiff as the other!

Coffees all around perhaps. Negligible x 2 is still negligible...

[A Muzi]

-snip frame flex-
Sandy wrote:
> On the other hand, headset reducers exist for 1 1/8" headtubes to hold 1"
> fork shafts, but I don't think they are thought of as especially stable.

Think of it as a thick headset cup; No technical reason not to and no
problems with them at all. Useful especially on new touring bikes where
a threaded fork tall and easily changed stem height is desired.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

[Tom Nakashima]

<jobst.brandt@stanfordalumni.org> wrote in message
news:4790dea8$0$36375$742ec2ed@news.sonic.net...
>
> Since switching to swiveling head bearings (Shimano) I haven't
> had dimples in the races (indexed steering) from fretting damage.
> Jobst Brandt

On the subject dimpling with ball bearings in headsets, will small diameter
balls prolong the races?
I know I need to switch over to the swiveling head bearings someday.
-tom

[jobst.brandt@stanfordalumni.org]

Tom Nakashima writes:

>> Since switching to swiveling head bearings (Shimano) I haven't had
>> dimples in the races (indexed steering) from fretting damage.

> On the subject dimpling with ball bearings in headsets, will small
> diameter balls prolong the races? I know I need to switch over to
> the swiveling head bearings someday.

I don't know which effect is greater, contact pressure or ball
rotation. However, larger bearing balls have usually been the better
course even though the number of balls for a given circle decreases
with increasing ball size. I'm still using the angular contact
pre-loaded cartridge bearings I had before converting to threadless.
That required boring out the threads and putting a conical seat in the
upper bearing mount to receive the centering cone. It looks like a
typical threaded head bearing.

Jobst Brandt

[Tom Nakashima]

<jobst.brandt@stanfordalumni.org> wrote in message
news:4790f301$0$36404$742ec2ed@news.sonic.net...
> Tom Nakashima writes:
>
>>> Since switching to swiveling head bearings (Shimano) I haven't had
>>> dimples in the races (indexed steering) from fretting damage.
>
>> On the subject dimpling with ball bearings in headsets, will small
>> diameter balls prolong the races? I know I need to switch over to
>> the swiveling head bearings someday.
>
> I don't know which effect is greater, contact pressure or ball
> rotation. However, larger bearing balls have usually been the better
> course even though the number of balls for a given circle decreases
> with increasing ball size. I'm still using the angular contact
> pre-loaded cartridge bearings I had before converting to threadless.
> That required boring out the threads and putting a conical seat in the
> upper bearing mount to receive the centering cone. It looks like a
> typical threaded head bearing.
>
> Jobst Brandt

I remember you telling me this, but was meaning to ask you about the
conical cone angle, how did you get the right conical cone angle in the
seat?
Or is angle not critical?
Also aren't the seats hardened?
-tom

[jobst.brandt@stanfordalumni.org]

Tom Nakashima writes:

>>>> Since switching to swiveling head bearings (Shimano) I haven't
>>>> had dimples in the races (indexed steering) from fretting damage.

>>> On the subject dimpling with ball bearings in headsets, will small
>>> diameter balls prolong the races? I know I need to switch over to
>>> the swiveling head bearings someday.

>> I don't know which effect is greater, contact pressure or ball
>> rotation. However, larger bearing balls have usually been the
>> better course even though the number of balls for a given circle
>> decreases with increasing ball size. I'm still using the angular
>> contact pre-loaded cartridge bearings I had before converting to
>> threadless. That required boring out the threads and putting a
>> conical seat in the upper bearing mount to receive the centering
>> cone. It looks like a typical threaded head bearing.

> I remember you telling me this, but was meaning to ask you about the
> conical cone angle, how did you get the right conical cone angle in
> the seat? Or is angle not critical? Also aren't the seats
> hardened?

No hardening, all parts are aluminum. The centering cone is a one
slot split ring with a 60° angle so that when it is pushed in axially,
it clamps the steertube and centers the upper bearing cup. I
saw no reason to buy a new head-set and had my old one modified.

http://en.wikipedia.org/wiki/Image:Threadless-bicycle-headset.jpg

Jobst Brandt

[Tom Nakashima]

<jobst.brandt@stanfordalumni.org> wrote in message
news:4790feca$0$36392$742ec2ed@news.sonic.net...
Tom Nakashima writes:

>>>> Since switching to swiveling head bearings (Shimano) I haven't
>>>> had dimples in the races (indexed steering) from fretting damage.

>>> On the subject dimpling with ball bearings in headsets, will small
>>> diameter balls prolong the races? I know I need to switch over to
>>> the swiveling head bearings someday.

>> I don't know which effect is greater, contact pressure or ball
>> rotation. However, larger bearing balls have usually been the
>> better course even though the number of balls for a given circle
>> decreases with increasing ball size. I'm still using the angular
>> contact pre-loaded cartridge bearings I had before converting to
>> threadless. That required boring out the threads and putting a
>> conical seat in the upper bearing mount to receive the centering
>> cone. It looks like a typical threaded head bearing.

> I remember you telling me this, but was meaning to ask you about the
> conical cone angle, how did you get the right conical cone angle in
> the seat? Or is angle not critical? Also aren't the seats
> hardened?

>>No hardening, all parts are aluminum. The centering cone is a one
slot split ring with a 60° angle so that when it is pushed in axially,
it clamps the steertube and centers the upper bearing cup. I
saw no reason to buy a new head-set and had my old one modified.

http://en.wikipedia.org/wiki/Image:Threadless-bicycle-headset.jpg

>>Jobst Brandt

Thanks for the link and the description, I can see it now.
As for the steering column, Dale Saso recommended cutting the original
and brazing a short tube to fit over, and then adding a 1.00" dia. tube to
extend. Making an extension to the steering column to accommodate swiveling
bearing headset instad of just brazing on a whole new steering column.
Your comments on the extension?
-tom

[jobst.brandt@stanfordalumni.org]

Tom Nakashima writes:

>>>>> Since switching to swiveling head bearings (Shimano) I haven't
>>>>> had dimples in the races (indexed steering) from fretting
>>>>> damage.

>>>> On the subject dimpling with ball bearings in headsets, will
>>>> small diameter balls prolong the races? I know I need to switch
>>>> over to the swiveling head bearings someday.

>>> I don't know which effect is greater, contact pressure or ball
>>> rotation. However, larger bearing balls have usually been the
>>> better course even though the number of balls for a given circle
>>> decreases with increasing ball size. I'm still using the angular
>>> contact pre-loaded cartridge bearings I had before converting to
>>> threadless. That required boring out the threads and putting a
>>> conical seat in the upper bearing mount to receive the centering
>>> cone. It looks like a typical threaded head bearing.

>> I remember you telling me this, but was meaning to ask you about
>> the conical cone angle, how did you get the right conical cone
>> angle in the seat? Or is angle not critical? Also aren't the
>> seats hardened?

> No hardening, all parts are aluminum. The centering cone is a one
> slot split ring with a 60? angle so that when it is pushed in
> axially, it clamps the steertube and centers the upper bearing cup.
> I saw no reason to buy a new head-set and had my old one modified.

http://en.wikipedia.org/wiki/Image:Threadless-bicycle-headset.jpg

> Thanks for the link and the description, I can see it now. As for
> the steering column, Dale Saso recommended cutting the original and
> brazing a short tube to fit over, and then adding a 1.00" dia. tube
> to extend. Making an extension to the steering column to
> accommodate swiveling bearing headset instead of just brazing on a
> whole new steering column. Your comments on the extension?

I got a new fork, mine being many miles old. I'm sure there are
various good ways of extending the steertube and I'd leave that up to
the frame builder. I meet riders who have had this done so it isn't
uncommon. I have an aluminum spacer tube to get my stem height the
same as before. Be careful and after being sure what fits best cut
the steertube to length.

You'll like adjusting head bearing with an Allen wrench, removing the
bars without untaping and removing a brake lever, removing the stem
without a hammer and the solid support. For me it was also getting
rid of corrosion stuck stems.

Jobst Brandt

[Tom Nakashima]

<jobst.brandt@stanfordalumni.org> wrote in message
news:4791088c$0$36344$742ec2ed@news.sonic.net...
> Tom Nakashima writes:
>
>>>>>> Since switching to swiveling head bearings (Shimano) I haven't
>>>>>> had dimples in the races (indexed steering) from fretting
>>>>>> damage.
>
>>>>> On the subject dimpling with ball bearings in headsets, will
>>>>> small diameter balls prolong the races? I know I need to switch
>>>>> over to the swiveling head bearings someday.
>
>>>> I don't know which effect is greater, contact pressure or ball
>>>> rotation. However, larger bearing balls have usually been the
>>>> better course even though the number of balls for a given circle
>>>> decreases with increasing ball size. I'm still using the angular
>>>> contact pre-loaded cartridge bearings I had before converting to
>>>> threadless. That required boring out the threads and putting a
>>>> conical seat in the upper bearing mount to receive the centering
>>>> cone. It looks like a typical threaded head bearing.
>
>>> I remember you telling me this, but was meaning to ask you about
>>> the conical cone angle, how did you get the right conical cone
>>> angle in the seat? Or is angle not critical? Also aren't the
>>> seats hardened?
>
>> No hardening, all parts are aluminum. The centering cone is a one
>> slot split ring with a 60? angle so that when it is pushed in
>> axially, it clamps the steertube and centers the upper bearing cup.
>> I saw no reason to buy a new head-set and had my old one modified.
>
> http://en.wikipedia.org/wiki/Image:Threadless-bicycle-headset.jpg
>
>> Thanks for the link and the description, I can see it now. As for
>> the steering column, Dale Saso recommended cutting the original and
>> brazing a short tube to fit over, and then adding a 1.00" dia. tube
>> to extend. Making an extension to the steering column to
>> accommodate swiveling bearing headset instead of just brazing on a
>> whole new steering column. Your comments on the extension?
>
> I got a new fork, mine being many miles old. I'm sure there are
> various good ways of extending the steertube and I'd leave that up to
> the frame builder. I meet riders who have had this done so it isn't
> uncommon. I have an aluminum spacer tube to get my stem height the
> same as before. Be careful and after being sure what fits best cut
> the steertube to length.
>
> You'll like adjusting head bearing with an Allen wrench, removing the
> bars without untaping and removing a brake lever, removing the stem
> without a hammer and the solid support. For me it was also getting
> rid of corrosion stuck stems.
>
> Jobst Brandt

I know, you already sold me on it last time...I just have to get it done.
Actually I'm going to call Saso to see when he can pencil me in.
My fork is still good, so I'll go with the extension, hanks for reminding
me on the height.
-tom

[jim beam]

Luke wrote:
> In article
> <3e866690-2c5e-43f5-bd0b-1608f94dea94@s13g2000prd.googlegroups.com>,
> bicycle_disciple <1.crazyboy.only@gmail.com> wrote:
>
>> On Jan 16, 2:08�pm, M-gineering <ikmotgeens...@m-gineering.nl> wrote:
>>> Tom_A wrote:
>>>> On Jan 16, 10:32 am, Thomas �Hood <thomas.h...@gmail.com> wrote:
>>>>> http://materials.open.ac.uk/bikeframes/bikeframe.htm
>>>>> Thomas Hood
>>>> Hmmm...seems to me that they should have hung the weight offset from
>>>> the BB to create a moment about the BB rather than in line with the
>>>> axle centerline and better simulate actual loading...
>>> bolting the dropouts to the table creates a restraint which isn't realistic
>>>
>
> Help me to understand why the degree of BB deflection decreases when
> the test frames have forks installed. I should think the opposite would
> be the case with the forks adding their own degree of flex to that of
> the frame.

in simple terms, it's like the deflection in the middle of a plank
between two bricks as opposed to a plank just sticking out on its own.
you would indeed expect deflection to be less.


>
> Unfortunately the testers' photos and description do not reveal how the
> forkless frames were secured to the testing jig;

the pics show it clearly - where the rear drops are mounted.


> could the fastening
> method be skewing the results?

of course. but since it's the same for all the frames, inconsistencies
are consistent and the relative results are useful.

[Sandy]

Dans le message de news:190120081240462696%lucasiragusa@rogers.com,
Luke <lucasiragusa@rogers.com> a réfléchi, et puis a déclaré :
> In article
> <3e866690-2c5e-43f5-bd0b-1608f94dea94@s13g2000prd.googlegroups.com>,
> bicycle_disciple <1.crazyboy.only@gmail.com> wrote:
>
>> On Jan 16, 2:08 pm, M-gineering <ikmotgeens...@m-gineering.nl> wrote:
>>> Tom_A wrote:
>>>> On Jan 16, 10:32 am, Thomas Hood <thomas.h...@gmail.com> wrote:
>>>>> http://materials.open.ac.uk/bikeframes/bikeframe.htm
>>>
>>>>> Thomas Hood
>>>
>>>> Hmmm...seems to me that they should have hung the weight offset
>>>> from the BB to create a moment about the BB rather than in line
>>>> with the axle centerline and better simulate actual loading...
>>>
>>> bolting the dropouts to the table creates a restraint which isn't
>>> realistic
>>>
>
> Help me to understand why the degree of BB deflection decreases when
> the test frames have forks installed. I should think the opposite
> would be the case with the forks adding their own degree of flex to
> that of the frame.

Actually, one measure is entirely missing: the headtube deflection. While
it has never been a popular reference in this forum, I suggest to anyone who
cares - take a look at a frame test done in Le Cycle magazine (FR). There,
each month, they take new frames through a series of deflection tests which
are similar to the study of this thread. They always refer the tested frame
to two others of a similar size, that were tested earlier (one tagged as
more rigid, and one tagged as more compliant). The fork element is taken
out of play.
--
Bonne route !

Sandy
Verneuil-sur-Seine FR

[Luke]

In article <ksSdnaZQQ-KTpg_anZ2dnUVZ_rOqnZ2d@speakeasy.net>, jim beam
<spamvortex@bad.example.net> wrote:

> Luke wrote:
> > In article
> > <3e866690-2c5e-43f5-bd0b-1608f94dea94@s13g2000prd.googlegroups.com>,
> > bicycle_disciple <1.crazyboy.only@gmail.com> wrote:
> >
> >> On Jan 16, 2:08�pm, M-gineering <ikmotgeens...@m-gineering.nl> wrote:
> >>> Tom_A wrote:
> >>>> On Jan 16, 10:32 am, Thomas �Hood <thomas.h...@gmail.com> wrote:
> >>>>> http://materials.open.ac.uk/bikeframes/bikeframe.htm
> >>>>> Thomas Hood
> >>>> Hmmm...seems to me that they should have hung the weight offset from
> >>>> the BB to create a moment about the BB rather than in line with the
> >>>> axle centerline and better simulate actual loading...
> >>> bolting the dropouts to the table creates a restraint which isn't
> >>> realistic
> >>>
> >
> > Help me to understand why the degree of BB deflection decreases when
> > the test frames have forks installed. I should think the opposite would
> > be the case with the forks adding their own degree of flex to that of
> > the frame.
>
> in simple terms, it's like the deflection in the middle of a plank
> between two bricks as opposed to a plank just sticking out on its own.
> you would indeed expect deflection to be less.
>
>
> >
> > Unfortunately the testers' photos and description do not reveal how the
> > forkless frames were secured to the testing jig;
>
> the pics show it clearly - where the rear drops are mounted.

Oh, I see. I had gotten it in my head that, sans forks, the frames were
supported in some fashion at the headtube, as your plank between two
bricks analogy. Don't assume as the saying goes...

[Luke]

In article <479281cd$0$28645$426a74cc@news.free.fr>, Sandy
<leurrre@free.fr> wrote:

> Dans le message de news:190120081240462696%lucasiragusa@rogers.com,
> Luke <lucasiragusa@rogers.com> a réfléchi, et puis a déclaré :
> > In article
> > <3e866690-2c5e-43f5-bd0b-1608f94dea94@s13g2000prd.googlegroups.com>,
> > bicycle_disciple <1.crazyboy.only@gmail.com> wrote:
> >
> >> On Jan 16, 2:08 pm, M-gineering <ikmotgeens...@m-gineering.nl> wrote:
> >>> Tom_A wrote:
> >>>> On Jan 16, 10:32 am, Thomas Hood <thomas.h...@gmail.com> wrote:
> >>>>> http://materials.open.ac.uk/bikeframes/bikeframe.htm
> >>>
> >>>>> Thomas Hood
> >>>
> >>>> Hmmm...seems to me that they should have hung the weight offset
> >>>> from the BB to create a moment about the BB rather than in line
> >>>> with the axle centerline and better simulate actual loading...
> >>>
> >>> bolting the dropouts to the table creates a restraint which isn't
> >>> realistic
> >>>
> >
> > Help me to understand why the degree of BB deflection decreases when
> > the test frames have forks installed. I should think the opposite
> > would be the case with the forks adding their own degree of flex to
> > that of the frame.
>
> Actually, one measure is entirely missing: the headtube deflection.

<snip>

I would've liked to see the deflection tests conducted with the frames
(sans forks) secured at the headtube as well as the rear drops.

[Bill Sornson]

Michael Press wrote:
> In article
> <18562e37-5236-4800-9bcc-355e3b2a2ecf@d21g2000prf.googlegroups.com>,
> Thomas Hood <thomas.hood@gmail.com> wrote:
>
>> On 17 Jan, 22:33, jobst.bra...@stanfordalumni.org wrote:
>>> Thomas Hood writes:
>>>> If you had to purchase a handlebar now, you would not be able to
>>>> purchase a steel handlebar. Given this constraint, is the 31.8 mm
>>>> oversize standard (http://tinyurl.com/28a8up) better from a
>>>> durability point of view?
>>>
>>> That's not germane, the pint is that I achieved a great improvement
>>> in rigidity, one that was entirely the quill stem replacement.
>>
>> I understand the point about the stem, I was just using it as a
>> segway
>
>
> ^^^^^^ segue

Beat ya to it by a day and a half. (And my arrows didn't line up, either.)

[Michael Press]

In article <4792b7c0$0$22663$4c368faf@roadrunner.com>,
"Bill Sornson" <askme@ask.me> wrote:

> Michael Press wrote:
> > In article
> > <18562e37-5236-4800-9bcc-355e3b2a2ecf@d21g2000prf.googlegroups.com>,
> > Thomas Hood <thomas.hood@gmail.com> wrote:
> >
> >> On 17 Jan, 22:33, jobst.bra...@stanfordalumni.org wrote:
> >>> Thomas Hood writes:
> >>>> If you had to purchase a handlebar now, you would not be able to
> >>>> purchase a steel handlebar. Given this constraint, is the 31.8 mm
> >>>> oversize standard (http://tinyurl.com/28a8up) better from a
> >>>> durability point of view?
> >>>
> >>> That's not germane, the pint is that I achieved a great improvement
> >>> in rigidity, one that was entirely the quill stem replacement.
> >>
> >> I understand the point about the stem, I was just using it as a
> >> segway
> >
> >
> > ^^^^^^ segue
>
> Beat ya to it by a day and a half. (And my arrows didn't line up, either.)

Yes, you did. I am in violation of usenet rule 38,
but you'll never take me ya filthy screws. Ha ha ha ha ha ha ha!

--
Michael Press

[Bill Sornson]

Michael Press wrote:
> In article <4792b7c0$0$22663$4c368faf@roadrunner.com>,
> "Bill Sornson" <askme@ask.me> wrote:
>> Michael Press wrote:
>>> Thomas Hood <thomas.hood@gmail.com> wrote:

>>>> I understand the point about the stem, I was just using it as a
>>>> segway

>>> ^^^^^^ segue

>> Beat ya to it by a day and a half. (And my arrows didn't line up,
>> either.)

> Yes, you did. I am in violation of usenet rule 38,
> but you'll never take me ya filthy screws. Ha ha ha ha ha ha ha!

Here, sign this. (Just watched "Rescue Dawn" -- terrific flick.)