How to find the right Bike Cassettes & Freewheels AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Bike Cassettes & Freewheels
- Cassette vs freewheel
- Freewheels thread onto the hub (common on budget bikes, typically ISO 1.375 inch by 24 TPI). Cassettes slide onto a splined freehub body and are held by a lockring. They are not interchangeable. You must buy the type your rear hub uses.
- Freehub body fit
- Shimano HG 8-10 speed bodies accept 8, 9 and 10-speed cassettes and 11-speed MTB cassettes. 11-speed road cassettes need the longer 11-speed road HG body. Micro Spline, XD and XDR each need their own body. An 8-10 speed cassette on an 11-speed road body needs a 1.85mm spacer behind it.
- Speed count
- Match the cassette speed count to your shifter and chain. Cog pitch differs with speed count, so mismatches will not index.
- Range vs derailleur capacity
- Do not exceed your rear derailleur's rated maximum cog size or total capacity. Exceeding the derailleur rating causes chain slack problems, or makes the largest cog unreachable.
- Cog material
- Steel cogs wear slower. Aluminium or titanium large cogs save weight but wear faster. Higher-tier cassettes are lighter but not always longer-lasting.
Brands that matter
- Shimano: Cassettes in HG, Micro Spline and road formats from budget to race tiers.
- SRAM: XD and XDR cassettes for 1x MTB and road, plus some HG-fit models.
- SunRace: Value, wide-range cassettes in Shimano-compatible fits.
- microSHIFT: Budget cassettes and freewheels.
- Campagnolo: Cassettes for Campagnolo freehubs only.
- e*thirteen: Wide-range MTB cassettes.
What to avoid
- Buying a cassette for a bike that actually has a threaded freewheel, or the reverse.
- Fitting a 12-speed Shimano MTB cassette to a standard HG body (it needs Micro Spline).
- Ignoring the derailleur's maximum cog size when choosing a wider range.
Questions
How do I tell if I have a freewheel or a cassette?
Look at the removal tool interface. A freewheel's splines spin with the cogs when you pedal backward. A cassette's lockring stays fixed relative to the cogs on a separate freehub body.
Can I put a SRAM cassette on a Shimano hub?
Yes for SRAM's HG-fit cassettes of the same speed count. XD and XDR cassettes need the matching freehub body.