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NEO Smart Trainer: The Derailleur or Chain is Contacting the Flywheel
In the event that the cassette installed on your Tacx® NEO series smart trainer trainer is caught on the trainer flywheel or the derailleur or chain is hitting the flywheel while positioned in the low gear, it will be necessary to move the cassette farther from the flywheel by installing spacers to resolve the contact issue.
Steps to Install the 1mm and 0.5mm Cassette Hub Spacers:
Remove the axle endcap from the NEO Smart Trainer using a 5mm allen wrench (QR) or 17mm cone wrench (Thru-axle), depending on endcap type.
Remove the freehub body and black sleeve from the axle by sliding them off the ax
Slide either the 0.5mm and 1mm cassette hub spacers onto the trainer axle. If necessary you can install both.
NOTE: Campagnolo Super Record 12 or Chorus 12 Speed cassettes require the use of both spacers.
Slide the freehub body and black sleeve back onto the trainer axle.
Flatten the spring-loaded pawls on the freehub body so it can insert fully into the trainer.
Re-install the axle endcap with a 5mm allen wrench or 17mm cone wrench, tighten until snug.
Video Tutorial
The following video covers the installation of the cassette hub spacer onto the trainer's axle.
Support: Free Hub Body Replacement on NEO Trainers