[adriano]

I feel a bit stupid. I must replace the smallest and the middle chainrings in my Shimano XTR FC-M985 front drivetrain. There are two possible ways to orient the chainrings, and I do not know which one is correct. I disassembled the old chainrings without paying attention. The Shimano instruction sheet, as far as I can see, does not specify how to orient the chainrings - they probably assume that nobody can possibly be so dumb that he wouldn't know! Can somebody help me, please?

 

[aerius]

Take a look at the picture below. On the smaller chainring, you'll see a small tab in the 12 o' clock position. All Shimano middle & inner chainrings have this tab on them, you lineup the tab with the crank arm and you're done. Also note that the chainrings in the photo are shown with the outside facing the viewer. When you intall the chainrings on the crank, you want them to look the same way when looking at the bike from the right side.

 

[adriano]

Thank you Aerius, very helpful and kind. Now, the middle ring. One side has a relatively smooth composite, while the other has a more complex pattern. Am I right in assuming that the smooth side goes outside? I assume that the complex pattern's reason of being is to help shifting from the small chainring. Many thanks in advance.

 

[aerius]

Correct. The more complex side with all the ramps & pins faces the inside to help with shifting.