Write down the complete system
Record the shifter, rear derailleur, cassette and chain model codes, rear sprocket count and number of front chainrings. Include the smallest and largest tooth counts. For a wheel-related purchase, identify whether the bike uses a cassette or a threaded freewheel. A familiar brand name or a broad label such as 10-speed leaves too much unspecified.
Check the shifter and derailleur pairing
Indexed shifting depends on a supported combination, not just equal speed counts. Check the exact family and generation. A useful example: microSHIFT lists its Advent MX 11 cassette as compatible with Shimano CUES, while its MX shifter and derailleur remain within microSHIFT's specified combinations. Compatibility of one component does not transfer to the whole groupset.
Match the cassette to the hub
Confirm the exact freehub or driver-body standard in the cassette specification. HG, MICRO SPLINE, XD and XDR are not interchangeable labels. SRAM distinguishes XD from the longer XDR interface and documents specific spacer requirements for approved combinations. Ask for the complete required parts list; do not assume a cassette fits because it has the right number of sprockets.
A wider range needs another check
Compare a proposed cassette with the derailleur's permitted largest sprocket, total capacity and intended one- or multiple-chainring setup. These are distinct specifications. A replacement with more teeth is not automatically an easy climbing upgrade. Chainring changes also require the correct mounting interface, chainline and clearance, so include the crank model in an upgrade request.
Choose the chain by system
Use the manufacturer's chain specification rather than matching the package's speed number by instinct. Shimano's compatibility chart groups LINKGLIDE 9-, 10- and 11-speed systems with LINKGLIDE or specified HG 11-speed chains. That exception illustrates why the exact system matters. Confirm the approved connecting link or pin and the required chain length with the installer.
Your shopping checklist
For a straightforward replacement, compare the complete old and new part numbers first. For an upgrade, request confirmation of the whole proposed combination and any additional parts before ordering.
- Shifter and derailleur family, model and speed count.
- Cassette interface, tooth range and derailleur limits.
- Approved chain, connecting hardware and crank details.
Go to the source.
Check the current instructions and compatibility information for your exact component.
