Will a Shimano Deore RD-M5120 will work with an 11 speed 50 tooth cassette?
Because my xt needs some new jockey wheels and might be quite bent..something's bent in my drive chain
£25 for the rear mech or £15 just for jockey wheels.
You'd be better off using an M5100 or M6100 rear mech. the 6100 is pretty cheap here at £28 or £27 from their ebay shop with the discount code
https://sportandleisure.com/products/shimano-deore-m6100-12-speed-shadow-rear-derailleur
https://www.ebay.co.uk/itm/335365469977
You can't just swap in a 12 speed mech for a 10/11 speed one, can you?
yes you can, 11 and 12 share the same cable pull ratio so 5100 and 6100 work interchangeably (they appear to be as near as the same mech with slightly different finish).
10 speed pull ratio was slightly different but shimano made the 5120 mech an inbetween pull ratio which works with both.
If you've got a 50t max rear cassette then that's outside the range of the 5120 mech and you're much better off with the 5100 or 6100 for 11 speed (or 12).
Over the last couple of years I've been using M5100, M6100 and M7100 mechs on 11 speed cassettes with 50/51 granny bailouts. All good. Couple of points: the M6100 mech fell apart after c.6000km, pivots completely shot. The M7100, with new jockey wheels, is ok after similar mileage, waiting in the spares box to go back on the bike at some point. The M5100 mech currently in service is fine but only has c.3000km on it.
You can get new M7100 jockey wheels for <£7 at the moment (I bought two sets last week). I actually think jockeys with bushings are better than tiny sealed cartridge bearings for this application. Leaving aside your comment about something in your drivetrain being bent, if it was me I'd first try a set of SLX jockey wheels before buying a new derailleur. They'll work fine on your existing XT mech.
Thanks very much for that!
I've gone for the M6100 on eBay. Thanks for the link @cp 😃
Another bike had a 12 speed xt mech die. I replaced it with a m6100 and it was just as good, but not broken.
Is 10 speed really a diferent pull ratio?
I've using an m6100 12 speed long cage mech with 10 speed shifter and 10 speed 11-46t cassette and its all been working for for 2 years or so.
Changing 1st -> 2nd got slow for a bit, but I discovered the mech i was using had totally worn out jockey wheels with too much play compared to a new mech.
Is 10 speed really a diferent pull ratio?
Only very slightly. And only in the shifter. Use a 10spd shifter and cassette with an 11spd derailleur and it all works flawlessly.
This week I've learned that you can use a 12spd derailleur as well... thanks!
