Ultegra vs. Dura-Ace?

On Wed, 26 Nov 2003 12:00:14 GMT, B a r r y B u r k e J r .
wrote:

My OCLV with exactly the same setup also does that, but on the 2nd
largest cog. The chainline looks pretty hairy at that point, so I

I was working on an OCLV the other day. It had a Chorus crankest and
the proper Campy chorus bb. The owner told me that the frame came
with a bb that had a 106 mm installed but I never heard of anything
like that from Trek. I measured from the centerline of the frame to
the 39 chainring and the measurement came to less than the 43.5 mm
that Shimano likes to see. If that measurement is typical, than the
rubbing during cross chaining is easy to see.

Paul Kopit wrote:

I was working on an OCLV the other day. It had a Chorus crankest and
the proper Campy chorus bb. The owner told me that the frame came
with a bb that had a 106 mm installed but I never heard of anything
like that from Trek. I measured from the centerline of the frame to
the 39 chainring and the measurement came to less than the 43.5 mm
that Shimano likes to see. If that measurement is typical, than the
rubbing during cross chaining is easy to see.

On a double chainwheel system, the standard 43.5 mm chainline is
measured to the halfway point betwixt the two rings, not to the inner
ring.

Given the usual 5 mm-ish spacing betwen the rings, the measurement to
the inner ring would normally be about 41 mm.

See my Chainline article: http://sheldonbrown.com/chainline

Sheldon "Numbers" Brown
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| because she gives the test first, |
| the lesson after. -- Vernon Law |
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