Yurp. It's an M985 xtr shadow rear derailleur. So what? It's on Aaron Gwin's bike. It isnt stock. It's got a Saint short cage melded to what will be the standard parallelogram body. Whats so tough about that? it's been done before (see sicklines modded M972 xtr/Saint mech).
Well, i'm not so sure...see, the bolt that holds the body to the cage usually marries up to a stub axle on the outer cage, concentric with the pulley centre. If you look at the shimano tech docs for all these mechs, the Saint cage should be compatible with most xtr bodies, but the shadow has a different stub axle on the outer cage - much smaller in diameter. The attachment bolt seems quite different. I'm guessing that is because the mechanism that controls the damping of the movement of the mech is situated in the same area. 'Course at £135 for the shadow and £100 for the Saint, i dont want to attempt this and find it doesn't work without impossible-for-me modifications.
But why do i even want to do this in the first place? Well, i ride in Scotland. Scotland is home to heather. Heather and derailleurs don't mix at all well. Minimising contact between heather and derailleurs is paramount, especially if you are going to be out in the boonies. I really like the idea of using an i-spec mount for the new Vertigo, with a 1x10. 1x10 doesn't need the chain take up of a GS or SGS cage. Would i be willing to give up the Saint short cage to get the 10 speed ? (the throw geometry is differnt with the new 10 speed dyna sys, so i cant use all the 10 speed stuff with the 9 speed mech, and the i-spec mount isnt compatible with 9 speed shifters). Probably...
I'm also doing some surgery on an old M801 Saint mech. I want to thank Tim at Sideways Cycles for his help locating this part. Its for the pink bike, which is singlespeed specific, but on the odd occasion i want to be able to mount gears. The DT thru axles should mary up nicely and allow quick, easy conversions to 6 or 9 speeds. Sweet.
First stage is removing the SGS cage and bolting on an old ss cage. There is a 2mm allen bolt under the body that acts as a lock - easily done. Next is putting some different jockey wheels on. Upper will go to an alloy 11 tooth, Lower will be a 13 tooth alloy unit. Dunno, just want to give em a try.