Cassette and freehub compatibility: identify the driver before the speed count
Separate cassette tooth sequence, driver interface, exact hub-body permission and whole-drivetrain compatibility; a matching speed count is not an approval.
Published 11 October 2026 · OpenBikeFit
Four identities, three independent boundaries
- Cassette model/variant → declared cassette-facing driver interface.
- Exact driver body → exact receiving hub/wheel generation.
- Chain + controls + derailleur → separate system evidence.
- SRAM names XD/XDR separately; length difference 1.85 mm is scoped, not a universal spacer recipe.
Original schematic, not to scale. Identity cards are not spline drawings or installation steps. Unknown permission remains unresolved; no force or conversion instruction.
On this page
- 01Write four identities before interpreting a label
- 02Count and tooth sequence answer different questions
- 03Driver family names are not interchangeable
- 04A length difference is a scoped source fact
- 05The driver-to-hub boundary is another interface
- 06Read the scope of every table check mark
- 07Keep chain, control and derailleur evidence separate
- 08Prepare a question rather than an installation plan
Free gearing workspace
Compare complete gearing declarations
Retain every numerical tooth pairing, optional wheel quantities, source-specific constraints and unknowns. No ranking, chain-length instruction or compatibility verdict.
Open toolWrite four identities before interpreting a label
A useful compatibility question identifies the cassette model and tooth variant, its declared receiving interface, the installed driver-body model, and the exact hub or wheel model that accepts that body. Preserve the source date and revision. An 11-speed or 12-speed label is insufficient because it does not encode this whole chain of interfaces. A manufacturer name on both parts is also not a compatibility relationship.
Keep installed and proposed declarations in separate columns. If only the wheel name is known, the driver may still be unresolved because a wheel family can have multiple bodies or generations. A picture of exposed splines is a useful reference for a qualified check, not a reason for this browser guide to certify the hidden interface. Do not dismantle anything just to complete these notes.
Count and tooth sequence answer different questions
The number of sprockets describes rear positions. Their complete tooth sequence describes numerical gearing. Neither alone specifies the attachment system, chain family, shift indexing or permitted hub-body combination. A fictional twelve-position declaration with 10–44 endpoints and another twelve-position declaration with 11–44 endpoints need independent exact sources; one is not a variant of the other merely because the count agrees.
The previous guide owns range and adjacent-step calculations. Carry its raw inventory into the interface discussion without turning a desirable numerical endpoint into approval. If a catalogue gives only a range, mark middle teeth unknown. If it omits the driver interface, keep that unknown too. Resolving one missing quantity does not automatically resolve the others.
Driver family names are not interchangeable
HG, MICRO SPLINE, XD and XDR are interface-family labels, not different spellings of speed count. The exact source may distinguish variants inside a family, so preserve its complete wording rather than shortening everything to Shimano-compatible or SRAM-compatible. A family label helps locate the right documentation; it does not supply tolerances, contact lengths, retention details or a universal conversion.
SRAM explicitly distinguishes its XD and XDR driver interfaces. Its explanation is evidence about those named interfaces, not a claim that every SRAM cassette uses them. Likewise a Shimano table must be read for its stated models, columns and conditions, not converted into a brand-wide matrix. A familiar smallest-sprocket count can prompt a question but cannot replace exact component identity.
A length difference is a scoped source fact
SRAM describes XDR as 1.85 mm longer than XD and explains a specific XD-cassette-on-XDR condition. That is a scoped manufacturer statement, not this page prescribing a spacer for an unknown assembly. Keep the direction of the interface relationship, exact cassette and hub instructions, and all required conditions. Do not reverse the relationship or transfer its dimension to HG, MICRO SPLINE or a different hub.
The original schematic shows separate identity cards, not measured spline profiles, a machining drawing or an installation sequence. No spacer is inferred from an observed gap. A part that seems to start engaging is not evidence that its interface, retention or operating clearance is correct. Stop at unresolved permission; do not use force, an adapter or a tightening step to make a mathematical comparison appear physically true.
The driver-to-hub boundary is another interface
A cassette may be documented for a driver family while the proposed driver body is not documented for the particular hub. Name the actual body and the actual receiving hub, generation and axle/end-cap configuration. The inner body mechanism and connection are not established by the outer cassette interface label. There is no universal replacement-body instruction on this page.
Treat a proposed body conversion as its own manufacturer question, not an automatic remedy for a cassette mismatch. Record the exact source that permits the combination and any unresolved condition without carrying out the conversion. Frame and axle compatibility, wheel location and other receiving parts remain independent. A compatible outer family does not prove that an arbitrary body fits an arbitrary wheel.
Read the scope of every table check mark
A compatibility chart must be read by its title, named models, column meanings, variants and footnotes. Shimano C-299, for example, concerns spoke protectors and specified cassette/wheel combinations. A check mark in that table is not a whole-drivetrain verdict or a general cassette-to-freehub matrix. Preserve what the cell actually answers before adding it to a reference record.
This is a practical way to avoid evidence laundering: a genuine manufacturer source can still be used for the wrong question. Record the question answered, the model row, the relevant column and any exception. An absent cell or a dash should not silently become permission. If two current exact sources conflict, retain both and ask the manufacturer or qualified mechanic instead of choosing whichever allows the desired purchase.
Keep chain, control and derailleur evidence separate
Even after the cassette/driver and body/hub relationships are resolved, the chain, controls, rear derailleur and front system need their own named compatibility evidence. The same rear speed count does not establish chain design, indexing, electronic system generation or permitted tooth range. The next guide distinguishes total capacity from the independent largest and smallest sprocket limits.
The existing crankset-interface guide owns shell, spindle, chainring, chainline and lateral/clearance references. This article does not replace that owner or add an assembly verdict. Keep exact part identities across the whole record. Numerical gearing and interface evidence can both be available while a complete configuration remains unresolved; do not erase the latter because the ratio calculation is attractive.
Prepare a question rather than an installation plan
A complete technical question lists current and proposed cassette identities and tooth variants, driver family and exact body, receiving hub/wheel generation, axle configuration, chain/control/derailleur identities, sources and outstanding conditions. Distinguish a stated source permission from a physical inspection not yet performed. Record contradictions explicitly; do not relabel an unknown as probably fits.
Use the free blank worksheet with supplementary controlled paper notes; its general component and question spaces are not dedicated cassette fields. No account, upload, private record or installation action is needed to read this journey. It offers no torque, retention, spacer, lubrication or conversion recipe, and certifies no shifting, fit, safety or performance result. The next step is exact documentation and qualified physical assessment where needed, not forcing an unresolved assembly into place.
Practical questions
Frequently asked questions
Does matching twelve-speed count prove cassette compatibility?
No. Cassette/driver interface, exact body/hub permission, tooth variant, chain, controls and derailleur evidence are separate.
Can I infer a spacer from the XD/XDR length difference?
Not for an unidentified assembly. The manufacturer describes a specific directional relationship; follow exact current part documentation and qualified physical checks, not a universal spacer recipe from this guide.
Does an XDR-labelled body fit any hub?
No. The cassette-facing family does not identify or approve the body-to-hub connection. The exact receiving hub and body generation need their own documentation.
Does a check mark in a manufacturer chart approve the whole drivetrain?
Only the chart’s stated question is answered. Model rows, columns, variants, exceptions and the title determine its scope; other interfaces remain independent.