I just got a wahoo kickr core and bought a 9 speed casette for it. Went for a ride on zwift and after a few gear changes, things started getting loud and ugly. Eventually, the chain slipped completely off the bracket and I'll need to break the link and reattach.

I'm trying to diagnose what's gone wrong. In swapping from my 11 speed casette (Shimano 105 11-32) to 9 speed (Sora 11-30), what do I need to do to? Reindex gears? Change chain? Something else?

  • 1
    You need to specify what your set-up on your bike is! Do you have a 11sp chain, shifter & derailleur on your bike? If so, why on earth would you buy a 9sp cassette for the Wahoo Kickr? I'm confused... Jun 5, 2021 at 14:35

2 Answers 2


Why would you want to use a 9-s cassette? If your bike is 11-s the drive-train will not work and the chain is much too narrow. The indexing is wrong. It can't be adjusted because the spacing between the cogs is different in both systems. The wider 9-s chain might even destroy your RD by getting stuck in the derailleur cage.

Get an 11-speed cassette and you can forget those problems. It's the intended use for a direct drive trainer to remove the rear wheel and put the bike on the trainer.

  • 4
    Concur - I suspect the 9 speed cassette was cheaper than the 11 speed cassette, but it worked out as a false economy.
    – Criggie
    Jun 5, 2021 at 8:29
  • 1
    Yep that's exactly the reason. Looks like in cheaping out I'll end up having to buy twice...
    – bananafish
    Jun 5, 2021 at 9:18
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    @bananafish Since you didn't get much use out of the cassette you can probably resell it as lightly used. Bike parts are in short supply right now and you can probably get a reasonable amount of money for it.
    – Kibbee
    Jun 5, 2021 at 12:29
  • Great thanks - I'll try that
    – bananafish
    Jun 6, 2021 at 22:29

For the setup to work, you'd need to replace the shifter and derailleur. The shifter is needed to get the right number of clicks and correct cable pull between gears, and derailleur is needed because the Shimano changed the actuation ratio between 9 and 11 speeds.

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