Zipp 340 vs. Zipp 303

[zencycle]

I've been offered a set of NOS zipp 340s (ok, a few miles on them).
The 303 is allegedly the next generation of the 340? I've been told
the rims are the same. Is there a real difference here? Being the
skeptical curmudgeon I am, I can't see Zipp changing the model number
because some one at corporate was bored. What _did_ change?

[Ron Ruff]

Zipp changes the layup of their rims all the time even if there
*isn't* a change in the outer shape and/or model #. The current 303
rims are 44mm deep, and are heavier and stronger than the previous
38mm 303s. The 340s are quite old and I'm sure they have little in
common with the new 303 rims. For one thing, the tension limit was
80kg on older Zipp rims (now 100kg), so that should give you some idea
of their strength. The new shapes are also more aerodynamic.

[John Forrest Tomlinson]

On Fri, 27 Jul 2007 10:40:28 -0700, Ron Ruff <rruffrruff@yahoo.com>
wrote:

>Zipp changes the layup of their rims all the time even if there
>*isn't* a change in the outer shape and/or model #. The current 303
>rims are 44mm deep, and are heavier and stronger than the previous
>38mm 303s. The 340s are quite old and I'm sure they have little in
>common with the new 303 rims. For one thing, the tension limit was
>80kg on older Zipp rims (now 100kg), so that should give you some idea
>of their strength. The new shapes are also more aerodynamic.

Some older Zipp rims had the spoke holes drilled straight out, not
offset, which puts a bad bend in the spokes. I had a rear wheel that
was often breaking spokes and think that was the cause.

--
JT
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[Ron Ruff]

On Jul 28, 12:28 pm, John Forrest Tomlinson <usenetrem...@jt10000.com>
wrote:
> Some older Zipp rims had the spoke holes drilled straight out, not
> offset, which puts a bad bend in the spokes. I had a rear wheel that
> was often breaking spokes and think that was the cause.

I've heard that is true also, but there are other rims on the market
today that are center-drilled. Bending the spoke near the nipple so
that the nipple is better aligned with the hole solves this problem.

[John Forrest Tomlinson]

On Sat, 28 Jul 2007 23:23:40 -0700, Ron Ruff <rruffrruff@yahoo.com>
wrote:

>On Jul 28, 12:28 pm, John Forrest Tomlinson <usenetrem...@jt10000.com>
>wrote:
>> Some older Zipp rims had the spoke holes drilled straight out, not
>> offset, which puts a bad bend in the spokes. I had a rear wheel that
>> was often breaking spokes and think that was the cause.
>
>I've heard that is true also, but there are other rims on the market
>today that are center-drilled. Bending the spoke near the nipple so
>that the nipple is better aligned with the hole solves this problem.

It mitigates the problem.

--
JT
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