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What you need to set up the Tacx Flux S Smart

Quick answer

To ride the Tacx Flux S Smart you need the following parts. Add a 12-speed cassette on a Shimano/SRAM HG (HyperGlide) body (matching your bike’s drivetrain). You’ll also need the thru-axle adapter for your axle (sold separately).

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Your parts checklist

Cassette

Buy a 12-speed cassette for a Shimano/SRAM HG (HyperGlide) body, matching your bike’s rear-derailleur speed.

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Freehub body

Ships with a Shimano/SRAM HG (HyperGlide) body fitted.

Other freehub bodies you can fit (sold separately) if your bike uses a different drivetrain:

Thru-axle adapter

Sold separately — buy the manufacturer’s thru-axle adapter for your axle size.

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Mounting your bike

What the Tacx Flux S Smart actually asks of you, in order — resolved from its own spec, not a generic manual.

  1. Take the rear wheel off the bike. A direct-drive trainer replaces it entirely.
  2. Fit the adapter for your axle standard. This trainer covers 130 mm quick-release, 135 mm quick-release, 12 × 142 mm thru-axle and 12 × 148 mm Boost thru-axle, but the adapter is sold separately — check yours before the first ride.
  3. Fit a 12-speed cassette on the Shimano/SRAM HG (HyperGlide) freehub body, torque the lockring, then lower the bike on and engage the axle. The cassette must match your bike’s drivetrain, not the trainer.
  4. Spacer rule for the Shimano/SRAM HG (HyperGlide) body: an 11-speed cassette needs none, a 10-speed one needs the 1.85 mm spacer behind it. Getting this wrong is the usual cause of a cassette that will not seat or a lockring that bottoms out early.
  5. On 12-speed: Shimano road 12-speed fits this HG body, but Shimano 12-speed MTB needs a Micro Spline body and SRAM 12-speed road needs XDR — check which your bike uses before buying a cassette.
  6. Spin the cranks by hand before you clip in: the chain should run quiet and straight. Noise here almost always means chainline or cassette spacing, not a faulty trainer.

Before you buy

Frequently asked questions

It depends on the trainer: typically a cassette matching your bike’s speed on the right freehub body, and a thru-axle adapter if your frame is thru-axle. The checklist above resolves exactly which of these the Tacx Flux S Smart needs.