Reek said:
I thought 8 speed rings were just a bit wider than 9 speed rings. And 9 speed chains were just a bit narrower than 8 speed chains. So using 8 speed chains on 9 speed rings wasn't too bad but using 9 speed chains on 8 speed rings could lead to chain breakage.
Is this not correct?
REEK
All derailluer chains (and the teeth they ride on) are 3/32" wide. That's inside width on the chain. As the number of cogs goes up, it's the cog spacing and the outside width of the chain that shrinks. 9 speed rings sit a little closer together on the crankarm, which might, in theory, screw up front indexing, but enough people have done it that I wouldn't worry about it.
I've got customers using "7 speed" Campy cranksets and rings, no ramps, no pins, with Shimano STI. Works just fine. Without the ramps, it shifts a bit slower, maybe an extra 1/3 rotation of the crank before the shift is finished, but despite Shimano's marketing, it works.
Don'r blame the mechanics at your shop, either. Shimano's dealer information is as wrong as their consumer stuff. They'll tell everyone that you must match everything, or it won't work at all, but that's never been true.
--Shannon