I have had issues with the drivetrain on my bike. I believe I've pinned it down to two issues.

  1. The Shimano Deore XT SGS (long cage) 9 speed rear derailleur needs replacing. It was either damaged when off-roading or is just worn out.

  2. The rear derailleur is designed to work with a maximum difference in the chainrings of 22 teeth. I have a triple chainset of 46-36-24. A difference of 24 teeth.

My question is:

  1. Is it possible to replace my old Shimano Deore XT 9 speed rear derailleur with its 10-speed equivalent? Which is far easier to obtain. Would I have problems with the 9-speed chain passing through the cage? Can you see any other issues that might occur? One thing I've noticed is that the newer Shimano rear derailleurs don't seem to have cable barrel adjustment on the derailleur and I don't know how I will be able to make those finer adjustments to the shifting. My bike is old and has downtube shifters. 9 speed indexed for the rear and friction for the front derailleur.

I intend changing my 24 tooth chainring for a 26 and changing my cassette from 11-32 to 11-34. Hopefully leaving me with a similar range of gears. The Shimano rear derailleur I'm looking at is supposed to be able to handle up to a 36 tooth cog.

I don't want to downgrade my componentry, but if your response is negative. I'll either have to do that or move up to a 10-speed drivetrain.

  • 3
    M772 should still be available if you look around e-shops. And I don't think M592 would be much worse, even if it is just Deore, it is newer. Commented Sep 12, 2020 at 18:11
  • With 46-36-24 rings, the difference of the chainrings is 22 not 24!
    – Carel
    Commented Sep 13, 2020 at 7:02

1 Answer 1


10 Speed Shimano uses a different cable pull and cassettes have a different cog spacing, so you would need to change the cassette and shifter to go to a 10 Speed derailleur.

Going 2 over the maximum difference is unlikely to cause problems with Shimano and they are fairly forgiving. I would not worry about changing chain rings if its been working.

If you cannot find an M772 XT deraileur, Deore M591/592 9 speed derailleurs are readily available. While not XT, the performance difference will be an improvement over a worn XT and probably not noticeably different to XT. If the performance is a concern, you may need to wait till you can get an XT delivered (or upgrade to 10/11/12speed).

If you decide to change speeds, do some homework as to going 1x, costs/benefits etc.

  • I've run all the aforementioned derailleur's though the XT was M750. I felt the performance of the newer model Deore's (M591 & M592) was superior to the XT. The Alivo class of rear derailleur is also high quality and pretty sharp looking and the newest model (RD-M3100) remains a 9 speed so will function in your current set-up.
    – Jeff
    Commented Sep 15, 2020 at 16:49
  • I didn't test it, but all available sources state that Shimano up to 10 speed (inclusive) use same pull ratio with just few exceptions (e.g. Tiagra ST-4700). Commented Feb 5, 2022 at 9:29
  • MTB 10 speed is different ( Deore XT ) has a pull of 1.2, 7-9 speed ahve apull ratio of 1.7. bike.bikegremlin.com/1278/bicycle-rear-derailleur-compatibility/…
    – mattnz
    Commented Feb 5, 2022 at 19:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.