What you need to set up the Saris H3
To ride the Saris H3 you need the following parts. Add a 12-speed cassette on a Shimano/SRAM HG (HyperGlide) body (matching your bike’s drivetrain). The thru-axle adapters are included in the box.
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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.
Find on AmazonFreehub 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:
- SRAM XD Driver Body
- SRAM XDR Driver Body
Thru-axle adapter
Included in the box — no separate purchase.
Mounting your bike
What the Saris H3 actually asks of you, in order — resolved from its own spec, not a generic manual.
- Take the rear wheel off the bike. A direct-drive trainer replaces it entirely.
- Fit the end caps or thru-axle adapter for your frame. This trainer covers 130 mm quick-release, 135 mm quick-release, 12 × 142 mm thru-axle and 12 × 148 mm Boost thru-axle and ships the adapters in the box, so nothing extra to buy.
- 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.
- 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.
- 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.
- 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.