MTB Cassette on Trainer

I just purchased a Tacx Flux S direct drive trainer and currently have my road bike setup on it and have really enjoyed it. I have been using a wheel on Kinetic trainer for years and this feels much nicer and am enjoying ERG mode.

I want to set my mountain bike up on the trainer just to change things up a bit and see how it feels. Is it necessary to change out the cassette that I have on the trainer (Shimano 11-28)? Since I’m using ERG mode does it not matter or will the Sram GX eagle derailleur not work with the Shimano 11-28 cassette? Not a big deal to throw the eagle cassette on but just swapping bikes is easiest.

This wouldn’t be my constant setup but more for fun and to mix things up for a minute.

Official SRAM answer:

Can I use an Eagle™ chain on my 11-speed system?

No, Eagle™ chains are not compatible with 11-speed cassettes, derailleurs or rings.

That said, I have seen lots of comments from people using this very combo with no apparent or claimed issues. So, it’s officially unsupported, but you are free to experiment :stuck_out_tongue:


I’ve done it on my kickr in erg mode without any apparent issues. That said I threw an nx eagle cassette on it because it was cheap and it gave me some peace of mind.

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:man_facepalming: I’m an idiot. I completely forgot it is 12sp! Too many bikes with too many configurations… I’ll just throw the eagle cassette on. Thanks for the reminder.

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I think you may need to go with an NX cassette because I don’t think the Flux S is compatible with XD driver cassettes without swapping to the appropriate hub body.

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I don’t have a big a jump but my turbo and TT bike are 11-25. I usually use them together but sometimes I use the road bike instead which has a 11-28 cassette on its wheel. There’s no need for me to switch cassette the 11-25 turbo cassette works fine with the road bike (11-28 cassetes wheel)

The tolerances are fairly minor and a worn in 12 speed chain works.
That’s not to say it’s a good idea.

You’re right. Is your NX cassette 12sp?

I don’t have an NX cassette (I’ve got an old 9 speed MTB on my Flux S), but they make a 12 speed NX cassette that should work on a Microspline body, which should be correct for the standard setup on the Flux.

Edit: Not Microspline. HG hub body.


Update: Nevermind my Epic doesn’t work because the brain prevents it from seating on the trainer. C’est la vie

Your bike’s brain is so big, it literally is too smart for your smart trainer. :rofl: