I just purchased a new 2025 Trek Madone SL6 12 speed. When I put it on my Kicker (V6), it does not rotate backwards, with the chain going slack. Am I doing something incorrect in setup, etc. The cassette is a brand new Shimano 12 speed that I swapped out from the installed 11 speed that came with the Kicker. Thanks.
The two things I would want to check first are (1) that the drive side adapter is installed on the trainer because it will bind if not present, and if it is (2) that the derailleur is adjusted properly. There is no guarantee that the cassette on the trainer will be positioned in exactly the same spot as the cassette on the rear wheel.
First thing I would do would be to remove the bike from the trainer and then see if the cassette on the trainer will freely spin backwards. If it does, than the issue is with the bike or how you are mounting it on the trainer. As Paul mentioned, make sure you have the proper spacers so the cassette isn’t binding against the frame when mounted. Also, make sure the chain is routed properly when the bike is mounted. It could get shifted off of one of the rear derailleur pulleys which could cause it to bind up and not allow it to freely move backwards.
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Welcome to the Forums. This is Haziel from Zwift support. This is Haziel from Zwift support, and I wanted to reach out regarding your inquiry. I understand how important it is for everything to run smoothly with your new bike, and I’m here to help.
It’s really important to make sure that any spacers or adapters you’re using for the 11-speed configuration are set up correctly or removed as per the 12-speed guidelines. If the spacers aren’t adjusted properly, it might be affecting how the freehub engages, which can be frustrating.
Could you please double-check that your new cassette is installed correctly? It’s essential that the lockring is tightened to the recommended torque, as this can impact the smooth operation of the freehub and even cause the chain to lose tension.
I truly understand how important it is for your trainer to work seamlessly with your new bike, and we are here to support you through this process. please contact us at Support@zwift.com. We are glad to help you with any questions or concerns.