BikeToWork

What if any difference is there between 10 and 11 tooth pulleys besides the number of teeth? I have an XTR derrailleur and am considering replacing the pulleys with Forte aluminum pulleys, which come in 10 or 11 tooth varieties. The drivetrain is 27 speed. Which one is compatible? Thanx in advance for advice.

maddmaxx 

Both will work, but nominally, the 10 tooth is a replacement for 8 speed and earlier equipment and the 11 is for 9 speed. The reason Shimano changed was to have an odd number of pully teeth engaging an even number of chain links so that on every other pass any given tooth on the pully would engage an inner chain link or an outer. This is supposed to improve pully tooth wear.

Remember when you do the replacement, that the upper pully does not get the shim washers that the lower idler pully gets. This allows the pully to have a little lateral float as the chain moves around.

timmhaan

thanks for posting that! i think i need to double check out i installed mine.

maddmaxx 

That's how Shimano does it. It may not matter, it may affect the noise the derailleur makes, it may make for harsh shifts. If you like to experiment.........try both. If you are reasonably good with your fingers, you can slip the shims in and out whild just pulling the one bolt that goes through the upper pully.....