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Shimano FC-M552 Hollowtech II, 42x32x24T 175mm, 3x10 speed - can i change to 22T?

9K views 5 replies 4 participants last post by  PerthMTB 
#1 ·
I've got the Shimano FC-M552 Hollowtech II, 42x32x24T, 175mm, 3x10 speed. i picked up a 22T XT Shimano ring real cheap - Can anyone advise if i can use XT 22T for the front granny gear for my crankset? Would i need to adjust the front deraileur or will it be ok?
 
#2 ·
Shouldn't be a problem so long as its a 64 BCD bolt pattern. You may get a little bit of chain rub on the bottom of the cage when in the smaller gears on the cassette, but you shouldn't use these much anyway, and if its a rear suspension bike, the suspension sag when you sit on it should lift the chain clear.
 
#4 ·
Shimano don't recommend it.

A 10spd 24t ring and a 22t 9spd ring will have slightly different chain-lines due to there "shape".

Some on this forum claim that it works.
 
#6 ·
Some on this forum claim that it works.
Yep, you can count me in with that group!

There's a lot of theorising and guesswork around on the topic, so one day I just decided to find out for myself. After a couple of hours with a vernier calliper measuring every conceivable dimension of a 9sp and 10sp Shimano crankset to an accuracy of 0.02mm, the facts are that the chainwheels are the same width, the spacing between chainwheels is the same, and the chainline is the same - so for all intents and purposes they are the same.

In fact, there's much bigger differences within 9sp cranksets and 10sp cranksets than between them. Things like tooth cutout, ramps and pins alignment, and tooth phase, can all make a big difference to shifting. That's what those cryptic letters like AD, JK, AK etc. stamped on Shimano chainwheels are all about, it tells you whether chainwheels are a matched set or not. So, for example, putting a 36T 9sp chainring that was designed to work in a 26/36/48 combination, with a 9sp 22T/44T instead, will mess up your shifting a lot more than mixing and matching 9sp and 10sp rings of the same 'set'.
 
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