Tacx Flux S with Shimano Cassette


I just got a Tacx Flux S with a Shimano CS-R7000 cassette. My bike is a Canondale CAAD12 with a Shimano CS-5800 cassette.

I just installed the trainer and I’m hearing a mechanical sounds which seems to be coming from the chain. From what I see the chain doesn’t seem to align perfectly with the cassette on the trainer.

Questions :

  • Could it be because the cassette is not exactly the same between the bike and the trainer ?
  • Do I need to tune the shifter a bit ? If so, does that mean I will have to tune that back before riding outside ? How do you guys deal with that ?

Thanks !

  • Yes, this is something that happens between different wheels as well as wheel-off trainers. You don’t always have a problem, but it is quite common to need to make small adjustments when swapping like this.
  • Yes, usually a twist of the barrel adjuster on the rear derailleur will remedy the issue.
  • If you aren’t aware how to change it, some good videos on YouTube can help (Park’s are quite good).
  • Yes, if you adjust to suit one device (wheel or trainer) it means you have to “undo” that change when you swap back to the original device (wheel or trainer).
  • So, as you adjust and make changes, note the amount and direction of the change on the adjuster. You usually need to just reverse that when swapping back and you will be all set.
  • As with any adjustment like this, it may take a final tweak when using it the first time as some adjustments aren’t perfectly made from one direction to the other.
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Thanks Chad ! This is the best I was able to do : https://www.youtube.com/watch?v=6CGhCS2gcNc

Still “clicky” but I don’t think I can make it any better :frowning:

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That is totally good. If you are doing a workout in ERG and not shifting, you should be great.

My guess is that is even good if you choose to shift for different flywheel speeds as well, use Resistance modes or other apps in Simulation (like Zwift).

FWIW, I use an Ultegra block on my wheel, and 105 (R7000) on the trainer, and after the first couple of adjustments I’ve found the sweetspot so that it works on both without adjusting the tension each time.

Admittedly that might just mean I’ve got it somewhere in the middle and I could optimise it for either cassette, but hey :man_shrugging:

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Hi - This may be not the reason but if you are using a 10 speed on the Flux you need to add the washer included with your Flux first before the cassette to have it “roughly in the right position”

Something I forgot to do when changing from an 11 speed to 10 speed bike on the turbo and then wondered why there was an issue.


Thanks ! I ended up sending the Flux back and getting an Elite Direto II. Turns out the feeling on the Flux was not what I was expecting and it’s quite different on the Direto.

Thanks guys !

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Hey there, sorry to hi-jack. I am on the fence between the Flux S and the Direto, both of which are on sale right now. Do you mind sharing what made you go for the Direto in the end?