12 speed cassettes on direct drive trainers

Most direct-drive smart trainers on the market are designed for road bikes with anywhere from 8 to 11 speed gear cassette on the wheel. With 12 speed drivetrains occupying the top of the bike industry, I thought I’d add this post on how to select cassettes.

Here is our guide to Direct Drive Trainers.

If you’ve purchased a trainer where the cassette is not included, we recommend you purchase a cassette that closely matches what’s on your bike’s rear wheel for the best shifting performance and compatibility with the rest of your drivetrain.

  • The number of speeds should match what’s on your bike.
  • The gear range should also match (“11-28” means the smallest cog has 11 teeth, and the largest cog has 28). You can count the teeth to be sure, or look for the number stamped on the cog.
  • Ideally, the brand of the cassette should match the brand of your rear derailleur.

To install the cassette, please see our guide to Installing a Cassette.

Some bikes are equipped with a 12 speed cassette on the rear wheel. Most direct-drive trainers come with a freehub body compatible with 8 - 11 speed Shimano and SRAM road cassettes, so you may need to swap out the trainer’s stock freehub body before installing your cassette. Please check with your trainer’s manufacturer for additional info.

Campagnolo 11 and 12 speed cassettes will only fit on a Campagnolo-specific freehub body.

SRAM 12 speed road bike cassettes will only fit on a SRAM XDR freehub body

SRAM 12 speed mountain bike cassettes will fit either a SRAM XD freehub body, or an XDR freehub body with an additional 1.8 mm spacer.

Most trainer manufacturers make all three of these optional freehub body types to retrofit on their trainers.

Shimano introduced their 12 speed mountain bike drivetrains in 2019, and these cassettes fit a new Microspline freehub standard. At this time, we are not aware of trainer companies that have a Microspline retrofit, but we will update when this changes.

At present i’m using a wheel on an “older” turbo with my much older 1980s tri bike
It has a Shimano 600, 6 speed cassette, ( down tube shifters) will this fit on any of the direct drive turbos, if I decide to upgrade.
Not too much of a problem currently, as with trying tyre I do not get slip, and Garmin V3 pedals provide the power.

@SteveK

Hi, today’s direct-drive trainers will not work with bikes with less than 8 speeds on the cassette. A better route in your case is to use a trainer where you leave the rear wheel on the bike.

Two reasons for direct drive trainers being a poor choice in your instance:
A. The spacing of your frame at 126 mm is too tight to fit on the trainer’s axle, which is 130mm at its narrowest configuration. 4 mm doesn’t sound like much, but you do not want to stretch the frame apart and start wailing on the pedals. That frame will eventually crack from those stresses.

B. A 6 speed cassette will not fit on modern freehub bodies, such as the one on your trainer.

re: “today’s direct-drive trainers will not work with bikes with less than 8 speeds on the cassette”

7 Speed Bike on Wheel-off Trainers:
A seven speed bike will probably work on a modern direct drive trainer. There’s a YouTube video showing the concept and the adjustment that is needed for a seven speed cassette versus what’s needed for an eight, nine or ten speed cassette. Those 8, 9 and 10 speed cassettes will go straight onto the 11 speed direct drive trainer with a simple adapter. For 7 speed use, you need to add a second spacer, 4 or 4.5 MM, and file a couple of small indents in the aluminum spacer. Our local bike shop provided a 4mm spacer for a couple of dollars and we used a 7 speed triple from the 90s on a 2014 Wahoo KICKR for months.Here’s a video that helped me:

Sorta correct. A modern 7 speed cassette might physically attach on the trainer’s freehub body, but it’s not going to shift well on SteveK’s vintage 6 speed drivetrain. It’s apples vs oranges.

Your suggestion would be apples to apples for someone who has a 7 speed drivetrain on a bike manufactured in the past 10 years, though.