Rear-axle standards
The rear-axle standard decides whether a trainer can clamp your bike — and which adapter you need. Open a standard to see exactly which trainers support it.
Quick answer
There are two families: quick-release (130 mm road, 135 mm MTB) and thru-axle (12×142 road/gravel, 12×148 Boost MTB). Almost every modern direct-drive trainer supports all four with the included adapters; older or wheel-on trainers may need a separate thru-axle adapter.
Quick-release
130 mm quick-release
Rim-brake road bikes.
Quick-release135 mm quick-release
MTB and older disc-brake bikes with a quick-release skewer.
Thru-axle12 × 142 mm thru-axle
Modern disc-brake road and gravel bikes.
Thru-axle12 × 148 mm Boost thru-axle
Modern mountain bikes (Boost spacing).
Thru-axle12 × 135 mm thru-axle
Some gravel / cyclocross frames.
Thru-axle10 × 135 mm thru-axle
Legacy thru-axle road/CX frames.