Just thought I’d let everyone know of the success I’ve had in fitting an XTR M9000 rear derailleur to a 1×10 setup without modification.

I found that I was having some issues with my Hope 40t T-Rex “holding” onto the chain when shifting down, upon inspection I could see that the cage of my XT Shadow+ derailleur was the problem and was catching on the back of the T-Rex sprocket. I looked at the OneUp Rad cage as a solution, and from pictures on the web I could see how it worked by off-setting the upper pulley. However I recognised that the same offset was present on my old STX derailleur, so I stripped it with a view to swapping its cage with the XT Shadow one, unfortunately the older derailleurs have a wider mounting pin, so without lots of time consuming filing and cutting screw threads it wasn’t going to swap easy. So I started looking at all Shimano rear derailleurs on the web, and realised the new XTR M9000 had a significant offset to its upper pulley. I also found some information that suggested the cable pull of the new XTR M9000 was only 0.2mm more than existing 10 speed Shimano, so I thought I’d have a gamble and see if it would work, worst case I might have to put some washers under the cable clamp.
I duly purchased an XTR M9000 RD and fitted it and found that it worked perfectly in all gears, the pulley offset cured the shifting problem, and also gave a much better chain wrap around the 11t sprocket as well. I’ve been running this setup for about 5 weeks now and have covered about 500 miles, initially in some real sticky mud and I have to report that the RD has shifted perfectly every time.

Setup as follows:
Cassette – XT M771 Cassette with Hope T-Rex 40t & the 15t & 17t sprockets replaced with an XT 16t.
Shifter – Saint M820 10 speed (all Shimano MTB 10 speed have the same cable pull, so should all work).
Chain – Shimano XT 10 speed

Yes I’ve probably spent 3 times as much than buying the OneUp Rad cage, however the XTR pulley offset is greater so provides more of a benefit.

As a final note, until I did this no recent Shimano Shadow 9 or 10 speed RD has ever provided such smooth shifting as the old STX, and now I know why – the Shadow RD upper pulleys have no offset! Only changed to Shadow type to get a clutch to stop chain slap (I just can’t stand any drivetrain noises).

If anyone interested I’d be happy to post some pictures or diagrams up on Sunday.

do you think it would work with the 42T One-Up adapters ?

Cheers, good to know you can slowly transition rather than have to upgrade everything at same time.

Yes scu98rkr I think it would, the XTR RD has more pulley offset than OneUp’s own Rad cage so can’t see why not.

cheers sounds like I should of waited for this solution.

Good work, what length cage did you go for ? Medium or long?

Hi Cnud – I went for a medium cage on the M9000 – I have tried long cage XT when I had 1×9, it was too long, and I have tried short cage Zee when I first went 1×10, that was OK on a standard 11-36 but it was definitely too short with the 40 tooth T-Rex.

Haven’t actually tried this, but the XTR cage can be purchased as a spare part (approx £50), and it appears to have exactly the same fittings as an XT shadow+, so may offer a cheaper solution.

Never said in the original post, but I did swap the XTR jockey wheels for my old XT shadow+ ones, the reason for this was that the XTR wheels have cut outs which always fill-up with the clay/grass/straw combination that masquerades as bridleways/tracks around here, and I can’t be bothered to poke it out after every ride. The XT ones being smooth seem to shed this material off easily whilst in use.

Top info, thanks