lyle.coop

I'd like to upgrade my 11-speed Shimano m8000 xt 11-46T cassette to an 11-51. I see shimano makes a Deore CS M5100 11-51. Link below. Is that swap just a matter of swapping the cassette and adding a couple extra chain links or entirely new 11-speed chain?

I have a Shimano single front ring. XT-SM-CRM80. 30 tooth.

Alternatively, can I swap my 46 cassette cog for a 51 tooth cassette cog?

Shimano 11-speed cassette

AeroGut

Both of the M8000 rear derailleur options indicate a max cog of 46, and the medium cage version only has a total capacity of 39. Usually those specs are a bit conservative, but you may have trouble getting a 51 cog to work well, especially if you have the medium cage rather than the long cage M8000 derailleur. If it doesn't work, you can swap in the M5100 Deore rear derailleur, which is designed for the 11-51 cassette.

lyle.coop

Thanks AeroGut. I have the Shimano XT M8000 Shadow+ 11 Speed Rear Derailleur according to a receipt I dug up.

Edit ** How can I measure the derailleur to determine if it is a medium or long cage? ** I think shimano has a code for the cage length:

SS = short cage
GS = medium cage
SGS = long cage

Back on the trails after a 5 year absence and everyone is powering up the climbs with sram 52's or shimano 51's.

AeroGut

The long cage is visibly much longer. Take a look at pics online and compare to yours and it should be fairly obvious which one it is.

Kapusta

The XT M8000 RD won't take a 51t cog, regardless of the cage length. There are aftermarket gizmos like the Wolftooth Goatlink that might work.

You will likely need to either switch to the Deore M5100 RD mentioned above, or you can also use a Shimano 12 speed RD, as those are designed to handle that size cog and have the same pull ratios as the 11 sp RDs.

I am using a 12 speed XT RD with an XT 11 SP shifter and an 11sp 11-51t Sunrace Cassette on a standard HD freehub (which is what I assume you have).

Darth Lefty 

This is on your Canfield? Definitely don't half ass it. That's the kind of bike that works this stuff the hardest. It needs any leeway built into the design to handle the chain growth when the suspension moves. If it were a hard tail someone might tell you ehhhh, maybe and you could try it and maybe it would be ok.

Kapusta

Wow, a lot of Canfields around here.

Darth Lefty 

that's cause everyone on a forum is a conny-soor

lyle.coop

The Shimano 12 speed RD can run on an 11-speed chain? Looks like I have to get a new RD to run an 11-51T and the choice is whether to go 11-speed or 12-speed.

My 11 speed RD is a medium cage.

Kapusta

I have not heard it can’t.

I am running an 11 sp sram chain.

lyle.coop

Good point. I have 2016 Stan Flow EX rims with a NEO Hub. I'm not sure what hub type it is. I'll pull the cassette off and take a look.

lyle.coop

Can you tell from these pictures if this is a standard HD freehub? I'm getting ready to order the Deore CS M5100 11-51 cassette and want to make sure its compatible. Thanks

lyle.coop

Confirmed with "Stans No Hubs" that my hub is a standard Hyperglide (HG) hub that will take a Deore m5100 cassette. Looking forward to pedaling that 51 tooth gear uphill.

Thanks for the help guys.

Paul Barnard

What kind of stuff are you climbing where and 11-46 with a 30t chain ring isn't adequate?

Kapusta

Steep stuff, I would guess.

This is the MTB forum.

prj71

Not on the road that's for sure.

10-50 and 28t chainring on my full suspension mountain bike and fat bike. 11-46 and 28t on my hard tail and I wish I had lower gears on it at times.