Count your speeds
Count the sprockets on your current cassette, or the clicks on your right-hand shifter plus one. A new cassette must have the same number of speeds as your shifter. An 11-speed shifter needs an 11-speed cassette.
Check your freehub body
The freehub is the splined part of the rear hub the cassette slides onto. Take the cassette off, or look up your wheel's spec, to see which one you have.
| Freehub body | What it looks like | Fits |
|---|---|---|
| Shimano HG (8, 9, 10-speed and MTB 11-speed) | Long splines, one wider than the rest | Shimano and SRAM 8–11-speed MTB cassettes, plus 8–10-speed road |
| Shimano HG road 11-speed | As above, 1.85mm longer | Road 11 and 12-speed cassettes. Older 8–10-speed cassettes fit with a 1.85mm spacer behind them |
| Shimano Micro Spline | Many fine splines | Shimano 12-speed MTB cassettes (Deore and up) |
| SRAM XD | Short, with a screw thread | SRAM Eagle MTB cassettes with a 10-tooth smallest sprocket |
| SRAM XDR | XD plus 1.85mm | SRAM road AXS cassettes. XD cassettes fit with a 1.85mm spacer |
| Campagnolo | Its own spline pattern | Campagnolo cassettes only |
Check your rear mech's limits
Every rear mech has a largest sprocket it can reach and a total capacity (how much slack it can take up). Both are printed in its spec. For example, a Shimano 105 RD-R7000 short cage takes up to 30 teeth, and the medium cage up to 34.
Fitting a bigger cassette than your mech allows will cause poor shifting or worse, the mech hitting the sprockets.
Picking a range
- Road: 11-28 or 11-30 for fast, flat riding. 11-32 to 11-34 for hills.
- Gravel and 1x: 10-42 to 10-52 depending on your chainring.
- MTB 12-speed: 10-51 or 10-52 for the widest range.
A smaller jump between gears (a tighter range) feels smoother. A bigger range helps on steep climbs.
FAQs
Can I fit a 12-speed cassette to my 11-speed bike?
Only if you change the shifter and usually the mech and chain as well.
Will an 11-speed road cassette fit my older wheel?
Only if the freehub is the longer 11-speed road version. Older 8–10-speed road freehubs are too short.
Do I need a new chain with a new cassette?
Almost always. An old, worn chain will skip on new sprockets.