XTR M952 Short Cage - Maximum Rear tooth capacity

[Retrorockit]

looks a little short to my eye
I guess I don't like the RD to be that stretched out

but presumably this is on a 1x drive train right?

Yes this is the mid drive Ebike. But it's my 2004 Gary Fisher so Retro stuff lives on. Like Avid BB7s. Rapid Rise, and Revoshifter. FFW too.
The 33t total capacity RD leaves a little play at each end with the 29t range cassette. This is ridden long and hard daily. It even works under water.
This also has a Front Freewheel Mod. The cassette turns any time the wheel is turning. Sort of like an 8 speed fixie. I think I posted a video of that earlier. I had a longer derailleur hanger at one time, but the B screw is all that's actually needed.

 

[Retrorockit]

looks a little short to my eye
I guess I don't like the RD to be that stretched out

You may be right to some extent. With the zip tie mod to (softly) lock out the rear freewheel, if it needed to throw some slack into the top run of the chain downshifting at high speeds it would snap the breakaway zip tie even though it's supposed to just be there as a fail safe in case the chain gets hung up. I put a greased rubber ring between the hub flange and the cassette instead, now it just slips a bit if it gets too tight. I don't think with out the FFW mod there would have been anything to notice. The normal freewheel action can't push slack into top of the chain to begin with.
But in this extreme appplication it does run out of travel every now and then. but I routinely throw it into low gear at 20mph in anticipation of a stop in traffic, and nothing bad happens. If there's enough travel for an extra link in the chain I would say do it. A new cassette should have a new chain anyway. Just work your way down to something useful.
Just Rapid Rise was easier on things. You just fed cable into it while slowing down w/o pedaling but the shift didn't actually happen until you pedaled it into gear just before stopping, the freewheel was still active.. But FFW is real time shifting up or down pedaling or not. RR can still downshift when stopped. I'm having a lot of fun with this old school junk in a modern application. But when I say this has been stress tested I mean it.

 

[Retrorockit]

I swapped an SS cage Zee M640 onto a bike with an 11-40t cassette. It worked OK both as the FR version, and the DH version with a longer B screw. The DH has better wrap around the chain in high gear. But both are worse than my mid cage XTR. Also it isn't Rapid Rise.
So it seems SS cages can handle 40t cassettes. But the only Rapid Rise SS cage MTB drailleur is the M800 Saint Which require it's own hub and axle, and the hub takes it's own Larger than normal Center Lock brake rotors. Which like the axles no longer exist. What in hell does any of this have to do with XTR?
I'm working on it. I have a couple SS cage Saint derailleurs. One is NOS Rapid rise. The other is a used M801 Hi Normal SS.
I also have a couple rapid Rise LX derailleurs. One SGS the other GS.
So taking tools in hand I pulled the SS cage off of the used Saint, and pulled the SGS cage off of the LX.
The Saint SS cage mechanically fits the LX (probably fits XT, and XTR also). The cage stop pin was at a slightly different angle. Probably due to the Saints axle mount origins. But the hole to move the limit stop was already drilled. Tap it to M4x.7mm and install a bolt on limit pin and remove the old one. It lost a little spring tension doing that. I'll need to drill another hole for the end of the spring to wind it up some more. But I now have a conventional mount Rapid rise SS derailler for testing. IDK if I'll convert the GS cage XTR to SS. it's kind of a nice piece as is. But the GS XTR is 6" above the ground, and the SS Zee is 7". This could make a difference if you get squeezed up against a curb in traffic.

 

[Retrorockit]

I drilled the new hole to increase the tension on the spring. The inner plate sits flat on the workbench with the pulleys removed. A hand drill with a #41 bit worked just fine. The tension still seemed a liitle light compared to the GS cage LX part. But I tried the other Saint SS and it matches up. I've heard of 105 SSS cages on XTR also.
So it's not too hard to make your own SS cage whatever derailleur you like. I like Rapid Rise.
Weather is nice here so I'm going to go ride. IDK when i'll put this into service. Probably the Ebike since it 8s Rapid Rise. The Zee is already on the 11s XC bike.

 

[Betsy]

The only minor issue which it currently has is lifting the chain from the 36t middle ring onto the 49t large ring (i know these chainring sizes are not ideal but they were the only NOS Pace rings i could find)

The (friction) shift from middle to large works perfectly while the bike is on the bike stand but it's a struggle to lift the chain onto the 49t ring while force is being applied through the crank / while pedaling..

^This sorted itself out..

I think what happend is.. the chain and the large ring were NOS so there was nothing to offer any friction to lift the chain, the chain was just slipping betwen the fd and the large ring without lifting it onto the teeth.. but now the back side of the ring is a little scuffed up.. it's enough to grip the chain and lift it onto the top ring.. has been perfect for weeks now

 

[Retrorockit]

I ran a 48/32/26 setup for a long time. This was Shimano XT stuff with an LX 48t.. It shifted just fine. Maybe a little slowly but never a problem. The 26t was rarely used in my area. I don't think the size should be an issue.