 You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
As I understand it the XT M8000 mech comes with 11t jockey wheels. I've been offer a spare set of aftermarket 12t ones. Any reason they won't fit? Has anyone tried 12t jockey wheels in Shimano 11spd kit?
Not sure if they'll work, but I know someone that might want them for their Sram GX 11spd if you dont..
The only reason I can think of that might stop them working is that the 12T will be a slightly wider diameter and the position of the axle hole in the jockey arm will be designed for the width of an 11T so you might not have enough room on the b-tension screw for it to clear the bottom cog.
Try it and see, it's only a couple of minutes' work in a workstand.