I recently built up a bike out of the junk laying around home. The
rear never shifted right (9 speed shimano cassette, XT rder, DuraAce
bar-end shifters). It would sometimes move up and down a cog on its
own. After some use I became convinced that no amount of adjusting
would fix it, something was wrong.
The first thing I did was swap out the chain. The problem immediately
went away.
Then I examined the chain that I removed. It was a KMC 9-speed chain,
half of a Nashbar recumbent chain. (The replacement chain was SRAM 9
speed).
I used calipers to measure the pin width and it was ~6.8 mm, as it
should be. However, the width of chain at the outer side plates was
also ~6.8 mm. The SRAM chain had the same length pins but the
thickness at the side plates was ~6.2 mm.
I then pulled out sections of other 8 and 9 speed chains (I save all
the extra links from a new chain). Both Shimano and SRAM chains
consistently were about 0.5 mm narrower at the outer side plates than
at the pins.
I'm convinced that this KMC chain is unusable for 9-sp systems. Any
comments?
Tom