franandjohn- I have a Campy Chorus (2000) chain and cassette ridden about
6000 miles
(never in wet conditions). Infrequently as of late the chain will fall off
to the inside when I am shifting from small to large chainring. After
checking the derailleur's adjustment and it appearing correct, I thought
perhaps chain wear was the cause. I measured the chain for elongation on the
bike with an accurate ruler, and found none (exactly 12 inches rivet edge to
rivet edge).

According to several sources, my mileage is high for no elongation. Might
other aspects of the chain have worn, causing the intermittent shifting
problem? Should I replace it, or so long as there is no elongation there is
no need to do so? Does the cassette need to be replaced at the same time, or
do cassettes last longer than chains? Any other factors that could be
causing the shifting problem?


I answer-Most of the chain fall off problems I see are front der adjustment
related, not chain wear related. Chains do get more flexy over time and your
measurement idea is the best way to check it. If it is indeed at 12 inches for
a taught chain, no worry, adjust the front der. As the chain gets thrown around
up front, the adjustment, etc of the front der can change.

If you do change the chain, and the casette skips under pressure, it is indeed
worn out.





Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"