New to MTB - what cassette on Trainer

Hi all,
I have a stupid question but I’m somewhat puzzled.
I just started to ride MTB and wanted to also ride my MTB on the trainer. I own a Saris H3 that is equipped with a 11 speed Shimano cassette, as I used it with my TT bike.
My MTB has a 12 speed Shimano XT. Can I simply ride the same cassette knowing that shifting would not work gerat (but the ERG mode would not require shutting anyway)? Or would I need to swap cassette to a MTB specific one?

That’s what I do, not sure if it’s a problem though so I wouldn’t take my word. I use a 10 speed cassette with a 12 speed MTB, it would definitely be better with an 11 speed cassette as the cogs are slightly thinner. Probably best to make sure you have a really nice straight chain line.

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I wouldn’t do that, you’ll wear your chain out quickly, and a worn chain will damage the cassette and chainring on your MTB. It’s better to get a 12-speed cassette for the trainer, though it doesn’t need to be an MTB cassette.

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I was in the same position and bought a cheap 12 speed cassette off AliExpress that worked fine for MTB usage.

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Why is this an issue, the inner width of the chain is the same (only the outer width is different) and so is the pitch. Obviously the shifting would be rubbish with the indexing being wrong and gap between the cogs being too wide for the chain but in erg mode that shouldn’t matter.


Ditto, I don’t think there is any particular wear consideration if used in a single gear for ERG mode. This is one search results that seems to indicate the new 12s HG+ chain is compatible with 11s & 12s Shimano systems.

The New Hyperglide+ chain, with a model name CN-M9100, is made to work with 11 and 12-speed XTR M9100 Hyperglide+ cassettes.

Noting the above, once we start talking about SRAM Flat Top chains, that is a very different story. But that’s not relevant here since the OP is on Shimano 12s.

thanks all, I will try the 11 speed cassette.

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