Bikes Ranked
Which cassette fits your wheel: identifying your freehub body
After reading this you will know how to tell a cassette from a freewheel, what it takes to get the cassette off, which freehub body is on your wheel, which spec field on the cassette you are about to buy has to match it, and which two follow-on checks — chain and rear derailleur — decide whether the new cassette will work once it is on.
Your old cassette and your new cassette are both, say, 11-speed. That tells you how many sprockets are on each. It tells you nothing about whether either one will slide onto your wheel. The part that decides is the freehub body — the splined cylinder the cassette slides over — and several incompatible families of them are in circulation, some carrying cassettes of identical speed counts.
The governing rule: a cassette fits the freehub body it was designed for. Speed count is not a compatibility statement. Buy for the body, then check the chain, then check the derailleur.
The proof that speed count means nothing on its own is easiest to see in chains. KMC's X12 is a 12-speed chain. KMC's product page states compatibility with "SRAM EAGLE, and Campagnolo 12-speed systems", and adds a footnote: "Not Compatible with SRAM T-Type, eTAP and Flattop". Those are all 12-speed systems too. Same number, different interface. Cassettes behave the same way.
Step one: confirm you actually have a cassette
Some wheels — older bikes, lower-end bikes, some e-bikes — have a threaded freewheel instead, where the sprockets and the ratchet mechanism are one screwed-on unit. No cassette will fit those, and nothing below applies. There is a test that needs no tools. Take the rear wheel out, find the splined tool fitting in the center of the sprocket cluster, and spin the sprockets backwards. Sheldon Brown's reference gives the two outcomes: on a cassette, the "Lockring splines turn with sprockets when spun backwards"; on a freewheel, the "Extractor splines do not turn when sprockets are spun backwards".
Check the direction carefully, because it is easy to state backwards. Fitting turns with the cogs = cassette on a freehub, keep reading. Fitting stays still while the cogs turn = threaded freewheel, and this page does not apply to you. The mechanism explains it: a cassette lockring threads into the freehub body and clamps the sprocket stack, so it is rigidly joined to the cogs and must turn with them. The same source notes that cassette freehubs often have a distinctive bulge on the right end of the hub barrel, though it says this is not universal.
Step two: getting the cassette off
Identifying the body means looking at it bare, and that needs two tools, not one. You need a splined lockring tool that matches your cassette's fitting, and something to hold the sprockets while you turn the lockring anticlockwise — the sprockets freewheel in that direction otherwise. Campagnolo's 13s sprockets manual is explicit about the pair: remove the locknut "using Campagnolo tool UT-BB080 with a 24 mm Allen wrench and wrench with chain Campagnolo UT-CS060, or equivalent tool." The Shimano-side equivalent lockring tool is the TL-LR15, listed as being for "installing/removing lockrings for HG/IG cassettes and CenterLock disc brake rotors", with a 24 mm wrench drive.
The lockring fitting is not universal across brands, so match the tool to your cassette rather than assuming. If you do not have both tools, a shop will pull the cassette in a couple of minutes, and you can read the body while it is off.
Step three: identify the body, not the cassette
With the cassette off you are looking at the bare splined body. Counting splines resolves some cases and not others, so it is worth knowing in advance which.
| Family | Published by | Smallest cog the cited source allows | Distinguishing detail |
|---|---|---|---|
| HG (HyperGlide) | Shimano | At least 11T per ENVE; Shimano's C-731 publishes no minimum cog | Four lengths in Shimano's own table. Three share 9 effective spline teeth; the road 12-speed dedicated L2 body has 18 (see table below) |
| MICRO SPLINE | Shimano | 10T per ENVE | 23 fine splines; 26 mm body. Shimano's C-731 covers Shimano cassettes and within it marks MTB 12-speed only — it is not a statement about other makers' cassettes |
| XD | SRAM | Fewer than 11T; SRAM cites 10-tooth cog compatibility | SRAM states XD is for mountain bike hub applications |
| XDR | SRAM | Fewer than 11T; SRAM cites 10-tooth cog compatibility | SRAM states XDR is for road hub applications and is 1.85 mm longer than XD |
| N3W | Campagnolo | 9T observed — Campagnolo publishes 9-36T and 9-42T Ekar cassettes for it | 4.4 mm shorter than the classic Campagnolo body, same groove profiles |
| Classic Campagnolo | Campagnolo | Not published in the documents opened here — read your cassette's own specification | Still in service; 4.4 mm longer than N3W. ENVE lists Campagnolo freehub bodies as an option on its rim and disc road wheels |
Counting splines separates MICRO SPLINE (23) and the road 12-speed HG spline L2 (18) from everything else at a glance. It cannot separate HG spline L, M and S, because Shimano gives all three 9 effective spline teeth. Those three are told apart by length only: 36.75 mm, 34.9 mm and 31 mm. Shimano defines the measurement as the "length from the contact surface of the cassette of the free unit to the tip of the free unit" — from the shoulder the cassette seats against to the outboard tip of the splined body. The S body is 3.9 mm shorter than M, which a ruler will show. L and M differ by 1.85 mm, which they will not; that one needs a caliper, or the hub maker's stated field.
| FREEHUB type | Effective spline teeth | Outer length | MTB 12-sp | MTB 11-sp | ROAD 12-sp | ROAD 11-sp | 10/9/8-sp (All) | 7-sp (All) |
|---|---|---|---|---|---|---|---|---|
| MICRO SPLINE | 23 | 26 mm | yes | no | no | no | no | no |
| HG spline L2 | 18 | 37.65 mm | no | no | yes | no | no | no |
| HG spline L | 9 | 36.75 mm | no | yes *1 | yes (no footnote) | yes *3 | yes *2 | no |
| HG spline M | 9 | 34.9 mm | no | yes | no | no *4 | yes *5 | yes *6 |
| HG spline S | 9 | 31 mm | no | no | no | no | no | yes *7 |
- *1 — Need 1.85 mm low spacer. (Attached only to MTB 11-speed on HG spline L.)
- *2 — Need 1.85 mm low spacer and 1.0 mm spacer for the cassette below: CS-7900 / CS-7800 / CS-6700 / CS-6600 / CS-5700 / CS-5600 (1.0 mm spacer is included). (Attached only to 10/9/8-speed on HG spline L.)
- *3 — CS-HG800 / CS-HG700 / CS-RS400 of ROAD 11-speed are compatible with HG spline L by installing 1.85 mm spacer.
- *4 — CS-HG800 / CS-HG700 / CS-RS400 of ROAD 11-speed are compatible with HG spline M. (This is the exception list against a NOT-compatible mark — road 11-speed cassettes other than these three are marked incompatible with HG spline M.)
- *5 — Need 1.0 mm spacer for the 10-speed ROAD cassettes below: CS-7900 / CS-7800 / CS-6700 / CS-6600 / CS-5700 / CS-5600.
- *6 — Only CS-HG210-7 and CS-HG400-7 are compatible.
- *7 — Only CS-HG41-7, CS-HG200-7 and CS-HG20-7 are compatible.
Three things to take from that table. First, ROAD 11-speed on HG spline M is a dash, not a tick: Shimano marks it incompatible, and footnote *4 names CS-HG800, CS-HG700 and CS-RS400 as the only exceptions. If you have a 34.9 mm body and a road 11-speed cassette, check the part number against that footnote before ordering. Second, HG spline L is not road-only — Shimano marks it compatible with MTB 11-speed and with all 10/9/8-speed cassettes, each with its own stated spacer. Third, the footnotes attach to individual cells, not to whole rows: ROAD 12-speed on HG spline L carries no footnote at all, so no spacer is listed for that combination.
One arithmetic observation that makes the spacers easier to remember. 36.75 mm minus 34.9 mm is 1.85 mm — the L body is longer than the M body by exactly the thickness of the low spacer Shimano specifies in footnote *1 for putting an MTB 11-speed cassette on an L body. The spacer is making up the length difference between the two bodies. That is an inference from Shimano's own two numbers, not something Shimano states.
The SRAM case: XD and XDR are not interchangeable in both directions
SRAM states that "the XDR interface is 1.85mm longer than XD and is designed for road hub applications", that XD is for mountain bike applications, and that "XDR driver bodies are compatible with all XD cassettes when the cassette is installed with a 1.85mm spacer behind it." Note what that sentence does and does not cover. XD cassette onto an XDR body with a spacer: stated as supported. XDR cassette onto an XD body: SRAM's article does not address it, and there is no length to give back — the body is shorter than the cassette needs. Do not read the first statement as symmetrical.
The Campagnolo case
Campagnolo's Ekar 13-speed sprockets page describes the N3W freehub driver body as "highly versatile, featuring the same groove profiles as the classic Campagnolo body, but 4.4mm shorter and lighter", and says that "with appropriate lockrings and adaptors, N3W is also compatible with all current and forthcoming Campagnolo 12-, 11- and 10-speed systems, with retro-fit kits including readily available." The Ekar cassettes it lists for that body are 9-36T, 9-42T and 10-44T — so 9- and 10-tooth starts mount natively.
The lockring is where the starting sprocket size shows up. Campagnolo's 13s sprockets manual states that the sprockets "need to be fitted to an N3W Campagnolo body", that "for sprocket cassettes starting from Z9, the ring nut is built into the smallest sprocket assembly", and that the tightening torque differs by start — 45 Nm for Z9 cassettes, 40 Nm for Z10. Its 12s equivalent carries a blunter warning: "With the 12s Campagnolo sprockets use ONLY the specific lockring. Be sure to use the correct size lockring to properly tighten the assembly."
So read a Campagnolo product page with that in mind. The Record 13 cassette is published in 10-33 and 11-36, and the page states that "the proven N3W standard is fully maintained, with no need for adapters or dedicated hubs" — without distinguishing the two ranges. The 11-36 starts on an 11-tooth sprocket, which is the case Campagnolo elsewhere covers with the words "appropriate lockrings and adaptors". A separate part sold as a Campagnolo cassette lockring, code AC21-N3W, is listed by retailers as "13X11T" and described as an adapter to run a Campagnolo cassette on an N3W freehub body. Before ordering an 11-tooth-start cassette for an N3W body, check which lockring and ring your cassette ships with and which your body takes. The product page does not answer it.
Step four: the chain
Every derailleur chain shares a pitch of 1/2 inch (12.7 mm), and 9- through 12-speed chains share an inner width of 11/128 inch (2.18 mm). KMC's X12 listing shows both figures directly as 1/2" x 11/128". What narrows with speed count is the overall outer width, because the sprockets sit closer together.
| Speeds | Outer width |
|---|---|
| 8 | 7.0–7.3 mm |
| 9 | 6.5–6.7 mm |
| 10 (most) | 5.84–6.1 mm |
| 11 | 5.46–5.74 mm |
| 12 (SRAM MTB) | 5.25 mm |
| 12 (Campagnolo) | 5.15 mm |
| 13 (Campagnolo Ekar) | 4.9 mm |
Use that table to understand why the chain matters, not to choose one. Buy the chain your drivetrain manufacturer specifies for your groupset, because — as the KMC X12 example shows — a chain can be the right speed count and the wrong chain.
Step five: the derailleur, and which document covers yours
If the new cassette has a bigger largest sprocket or a wider spread than the old one, the derailleur becomes a live question. Shimano splits this across two documents, and picking the wrong one wastes your time.
For road, gravel and Metrea drivetrains (RD-R…, RD-RX…, RD-U…, RD-A…), the document is C-254, "Compatibility between rear derailleur and cassette gear teeth [ROAD, Gravel, METREA]". It sets models against named cassette ranges — 11-30T, 11-34T, 11-36T, 12-28T and so on, organised by speed count — and marks each combination compatible or not. It publishes ticks and dashes, not numbers, and it contains no MTB derailleurs at all.
For MTB the document is C-433, "Rear drivetrain compatibility [MTB, LIFESTYLE]". This one does publish a numeric field, and it is the field you want: Largest sprocket, given as a permitted range per model and per drivetrain configuration. Entries read like "RD-M9250-GS RD-M8250-GS (45T ≤ Largest sprocket ≤ 45T for 1x12-speed)" and "RD-M9000-SGS RD-M8000-SGS (40T ≤ Largest sprocket ≤ 46T for 1x11-speed, 42T for 2x11-speed)". Find your model, read its largest-sprocket range, and compare it against the largest sprocket on the cassette you want. Note that the limit changes between 1x and 2x on the same derailleur.
Your derailleur model number is stamped on the body and carries a cage-variant suffix — RD-M8100-SGS, RD-R7000-GS. Match it exactly, including the suffix, because the variants differ. Shimano's specification indexes list the models by groupset, with MTB and road on separate pages: the MTB index carries RD-M9100-GS/SGS, RD-M8200-SGS, RD-M8100-GS/SGS, RD-M8120-SGS and RD-M7100-SGS, and the road index carries RD-R8000-SS/GS, RD-R7100, RD-R7000-SS/GS, RD-4700-SS/GS and others. Those indexes are for confirming your model number; the compatibility documents are where the tooth limits live. A total-capacity figure per model was not found in any Shimano document opened for this page, so use the largest-sprocket limit in C-433, or the ticks in C-254, rather than a capacity calculation from a forum.
What to look up on your own equipment
- In your wheel or hub manufacturer's specification, find the freehub body type. It is a named field — HG, MICRO SPLINE, XD, XDR, N3W, Campagnolo — not something to judge by eye. If the hub names an HG variant, note which one, because L, M and S all have 9 splines.
- In the cassette manufacturer's specification, find the freehub body it requires. Same kind of named field. ENVE puts it plainly: "checking with the drivetrain or cassette manufacturer is the best confirmation of which freehub to pick."
- If the two names do not match, the cassette does not fit. No amount of force changes that.
- If your cassette appears in a C-731 footnote, work out which spacers it needs and whether they ship in the box. The 1.0 mm spacer for CS-7900 / 7800 / 6700 / 6600 / 5700 / 5600 is stated as included; the 1.85 mm low spacer is not described that way.
- Check whether your hub's freehub body is a replaceable part. ENVE states that "most rear hubs, including ENVE, allow for a complete freehub swap without the use of tools or re-dishing of the wheel." Whether yours does is a question for your hub's manufacturer — look for a freehub body listed as a spare part. If it is replaceable, that is a third option alongside changing the cassette or changing the wheel. Prices vary by hub; ask the hub maker.
A cassette that almost fits is not a fit. In a thread on MTBR, a rider could not push a worn 9-speed cassette onto a new hub of the same speed count. Replies attributed it to the cassette's condition and its steel spider against an aluminum freehub body, warning that it would "chew the s*** out of the freehub body" and that if it is hard to get on, "try getting it off when it cuts into the new freehub body." That thread is not a freehub-family mismatch — it is a worn part being forced — and it is reported rider experience, not a tested claim. Both failure modes are worth knowing apart: the wrong family does not go on at all, while a worn or ill-matched cassette goes on badly and damages the body. If it does not slide on with hand pressure, stop.
The method here is the same one that resolves tire fitment on /tire-rim-compatibility/ — find the standardized number both parts publish, and compare those, rather than comparing category names. It is also the same trap described on the frame sizing guide, where two bikes both labeled 'medium' are different bikes. 'Medium' and '12-speed' are labels. The spline count and the body length are the specification.
Check it on your own equipment
These take you to the manufacturers and standards bodies the page draws on, so you can look up your exact model.
- Manufacturer specification
Shimano C-731: FREEHUB and cassette spline compatibility (opens in a new tab)Shimano's own grid of five freehub body types with effective spline teeth and outer length for each, and a tick or dash for every cassette category, with numbered footnotes attached to individual cells. Read the cell for your body and your cassette category, then read any footnote marker on that exact cell — two of them are exception lists sitting against a NOT-compatible mark. Check your cassette's part number against the footnotes before ordering. — productinfo.shimano.com - Official support page
SRAM: XD and XDR driver body explained (opens in a new tab)SRAM's statement of the 1.85 mm length difference between XDR and XD, which body belongs on road versus mountain hubs, and the spacer rule for fitting XD cassettes to an XDR body. Note that the article states that direction only — it says nothing about fitting an XDR cassette to an XD body. — www.sram.com - Manufacturer specification
Shimano compatibility document index (opens in a new tab)The list of Shimano's compatibility documents by code, which is how you find the right one for your drivetrain instead of guessing. C-254 covers rear derailleur and cassette teeth for road, gravel and Metrea; C-433 covers MTB and Lifestyle rear drivetrains and publishes the Largest sprocket limit per model; C-649 covers LINKGLIDE cassettes, which C-731 excludes; C-817 covers 7-speed rear derailleurs and freehubs. — productinfo.shimano.com - Manufacturer specification
Campagnolo Ekar 13-speed sprockets specification (opens in a new tab)Campagnolo's statement that the N3W freehub driver body has the same groove profiles as the classic body but is 4.4 mm shorter, the three published cassette ranges for it (9-36T, 9-42T, 10-44T), and the qualifier that compatibility with Campagnolo's 12-, 11- and 10-speed systems comes with appropriate lockrings and adaptors. Use it as a model for the freehub field to find on your own cassette's page. — www.campagnolo.com
What this page does not tell you
- The freewheel-versus-cassette spin test is easy to state backwards, and an earlier draft of this page did exactly that. The direction given here — lockring fitting turns WITH the cogs on a cassette — is taken from Sheldon Brown's reference, which was opened directly, and matches the mechanism: the lockring threads into the freehub body and clamps the sprocket stack. Park Tool publishes the same test with photographs and is the better-illustrated source, but parktool.com serves an automated bot check to non-browser clients, so it was not opened and is not cited here. It is worth opening in a browser if you want the pictures.
- Shimano's C-731 table is reproduced here cell by cell, with footnote markers kept against the individual cells they are attached to, because summarising it into prose is where errors creep in. Two combinations in particular are easy to get wrong: ROAD 11-speed on HG spline M is marked NOT compatible except for three named cassettes, and HG spline L is not road-only. Read Shimano's own page against your specific cassette part number before you buy.
- bike.shimano.com and si.shimano.com both returned HTTP 403 to direct retrieval on 2026-09-22, so Shimano's Micro Spline technology page and its cassette dealer's manuals could not be opened. No claim on this page rests on them. The MICRO SPLINE figures here come from C-731 and from ENVE; a 10-51T cog range and a groupset list that appeared in an earlier draft were dropped because no source that could be opened supported them.
- The Campagnolo URL campagnolo.com/UK/en/CampyWorld/Products/n3w_hub, cited in an earlier draft, now redirects to Campagnolo's country selector and carries none of the N3W content. It has been replaced with Campagnolo's Ekar 13-speed sprockets page, which was opened and which carries the 4.4 mm figure and the groove-profile statement directly.
- Campagnolo's own wording that N3W works with other cassettes "with appropriate lockrings and adaptors" was read on a live Campagnolo page, and its 13s manual confirms the lockring arrangement and torque differ by starting sprocket size. The specific kit code AC21-N3W could not be confirmed on any Campagnolo page that would load — the Campagnolo support page for that kit redirects to the country selector — so it is attributed here only to retailer listings, which establish that the part exists and how it is described, not that it is required for any particular cassette. Confirm the lockring question with Campagnolo or your wheel maker before buying an 11-tooth-start cassette for an N3W body.
- The chain outer-width table is a compiled third-party reference, not a manufacturer specification, and none of its figures were confirmed against a chain manufacturer. Pitch and inner width were confirmed against KMC's own published X12 dimensions. Treat the outer widths as explanatory and buy the chain your drivetrain manufacturer names.
- No total-capacity figure is published on this page. Shimano's C-433 publishes a largest-sprocket range per MTB model, and C-254 publishes compatibility marks for road, gravel and Metrea; neither document opened here published a per-model total-capacity number, and Shimano's per-model specification pages did not return retrievable content. Those figures are omitted rather than guessed.
- Shimano's C-731 is a table of Shimano cassettes. It does not speak to cassettes from other makers that state Micro Spline, HG, XD, XDR or N3W compatibility. Micro Spline freehub bodies are sold on non-Shimano hubs — ENVE lists them on its M Series wheels — but no third-party Micro Spline cassette maker's own specification page could be opened on 2026-09-22, so none is cited. For any non-Shimano cassette, read the freehub field on that maker's specification.
- Cassette installation torque and lockring procedure affect how the wheel behaves under load. Campagnolo's figures are quoted here only as evidence that the lockring arrangement varies by cassette; follow your own cassette manufacturer's installation instructions for torque, which are not covered here.
- SRAM's per-cassette support section on freehub body requirements returned HTTP 403 and could not be opened, so no claim is drawn from it here. The XD/XDR article itself loaded and is the source for every SRAM figure on this page.
Sources
Manufacturers revise specifications. Every source below is dated — open it before you buy.
- Shimano document C-731 groups its cassette columns as MTB (12-speed, 11-speed), ROAD (12-speed, 11-speed) and All (10/9/8-speed, 7-speed), so the 10/9/8-speed and 7-speed columns are not MTB-only.
- Shimano's MICRO SPLINE freehub body has 23 effective spline teeth and a 26 mm outer length, and in C-731 is marked compatible with MTB 12-speed cassettes and with nothing else.
- Shimano's HG spline L2 freehub body has 18 effective spline teeth and a 37.65 mm outer length, and in C-731 is marked compatible with ROAD 12-speed only.
- Shimano's HG spline L freehub body has 9 effective spline teeth and a 36.75 mm outer length, and in C-731 is marked compatible with MTB 11-speed (footnote *1), ROAD 12-speed (no footnote), ROAD 11-speed (footnote *3) and 10/9/8-speed (footnote *2); 7-speed and MTB 12-speed are dashes.
- Shimano's HG spline M freehub body has 9 effective spline teeth and a 34.9 mm outer length, and in C-731 ROAD 11-speed is marked NOT compatible, carrying footnote *4; MTB 11-speed is a plain tick, 10/9/8-speed carries *5 and 7-speed carries *6.
- Shimano's HG spline S freehub body has 9 effective spline teeth and a 31 mm outer length, and in C-731 only the 7-speed column is ticked, carrying footnote *7.
- Shimano's C-731 footnote *1 reads "Need 1.85 mm low spacer" and is attached only to the MTB 11-speed cell of the HG spline L row.
- Shimano's C-731 footnote *2 requires a 1.85 mm low spacer plus a 1.0 mm spacer for CS-7900, CS-7800, CS-6700, CS-6600, CS-5700 and CS-5600, states the 1.0 mm spacer is included, and is attached only to the 10/9/8-speed cell of the HG spline L row.
- Shimano's C-731 footnote *3 states that CS-HG800, CS-HG700 and CS-RS400 road 11-speed cassettes are compatible with HG spline L by installing a 1.85 mm spacer.
- Shimano's C-731 footnote *4 states that CS-HG800, CS-HG700 and CS-RS400 road 11-speed cassettes are compatible with HG spline M, and it is attached to a NOT-compatible mark — so road 11-speed cassettes other than these three are marked incompatible with HG spline M.
- Shimano's C-731 footnote *5 requires a 1.0 mm spacer for the 10-speed ROAD cassettes CS-7900, CS-7800, CS-6700, CS-6600, CS-5700 and CS-5600 on the HG spline M body.
- Shimano's C-731 footnote *6 states that only CS-HG210-7 and CS-HG400-7 are compatible, and footnote *7 states that only CS-HG41-7, CS-HG200-7 and CS-HG20-7 are compatible.
- Shimano's freehub outer-length figure is measured as the length from the contact surface of the cassette of the free unit to the tip of the free unit.
- Shimano's C-731 states that the table does not include LINKGLIDE cassettes and directs readers to document C-649 for those.
- Shimano's C-731 lists four HG freehub variants, not three: HG spline L2 (18 effective spline teeth), HG spline L, HG spline M and HG spline S (9 each). Three share 9 spline teeth; L2 has 18.
- The difference in outer length between HG spline L (36.75 mm) and HG spline M (34.9 mm) is 1.85 mm — exactly the thickness of the low spacer Shimano specifies in footnote *1 for fitting an MTB 11-speed cassette to an HG spline L body. The gap between HG spline M and HG spline S is 3.9 mm.
- SRAM states that the XDR interface is 1.85 mm longer than XD and is designed for road hub applications, while XD is for mountain bike applications.
- SRAM states that XDR driver bodies are compatible with all XD cassettes when the cassette is installed with a 1.85 mm spacer behind it. SRAM's article does not address fitting XDR cassettes to XD driver bodies.
- SRAM states that both XD and XDR accommodate cassettes with cogs of fewer than 11 teeth, citing 10-tooth cog compatibility as what allows the expanded cassette range.
- On a cassette, the lockring splines turn with the sprockets when the sprockets are spun backwards; on a threaded freewheel, the extractor splines do not turn with the sprockets.
- Cassette freehubs often have a distinctive bulge on the right end of the hub barrel, though this is not universal.
- A cassette lockring threads into the freehub body and clamps the sprocket stack, which is why the lockring fitting is rigidly joined to the cogs and must turn with them.
- Campagnolo's 13s sprockets technical manual states that removing the locknut requires Campagnolo tool UT-BB080 with a 24 mm Allen wrench together with the Campagnolo chain wrench UT-CS060, or an equivalent tool — that is, a splined lockring tool plus a sprocket-holding tool.
- Campagnolo's 13s sprockets technical manual states that the sprockets need to be fitted to an N3W Campagnolo body, that for cassettes starting from Z9 the ring nut is built into the smallest sprocket assembly, and that tightening torque is 45 Nm for Z9-start cassettes and 40 Nm for Z10-start cassettes unless otherwise indicated on the locknut.
- Campagnolo's 12s sprockets technical manual warns that with 12s Campagnolo sprockets only the specific lockring should be used, and that an incorrect lockring could cause failure of the assembly.
- The Shimano TL-LR15 is sold as a tool for installing and removing lockrings for HG and IG cassettes and CenterLock disc brake rotors, with a 24 mm wrench drive, part number Y12009230.
- Campagnolo describes the N3W freehub driver body as having the same groove profiles as the classic Campagnolo body but 4.4 mm shorter and lighter.
- Campagnolo publishes Ekar 13-speed cassettes for the N3W body in 9-36T, 9-42T and 10-44T, so 9- and 10-tooth starting sprockets mount on N3W natively.
- Campagnolo states that with appropriate lockrings and adaptors, N3W is also compatible with current and forthcoming Campagnolo 12-, 11- and 10-speed systems, with retrofit kits readily available.
- Campagnolo's Record 13 cassette is published in 10-33 and 11-36, states that the N3W standard is fully maintained with no need for adapters or dedicated hubs, and draws no distinction between the two ranges.
- A part designated AC21-N3W is sold as a Campagnolo cassette lockring described as 13X11T and as an adapter to run a Campagnolo cassette on an N3W freehub body.
- The Record 13 11-36 cassette starts on an 11-tooth sprocket, which is the case Campagnolo covers elsewhere with the phrase "appropriate lockrings and adaptors", so the lockring and ring supplied with the cassette should be checked against the N3W body before ordering.
- ENVE states that HG is the standard used for cassettes that have at least an 11-tooth cog as the smallest cog. Shimano's C-731 publishes no minimum cog figure for any freehub body.
- ENVE states that Micro Spline is available with 2020 Shimano SLX, XT and XTR drivetrains and allows a wider-range 12-speed cassette with a 10-tooth cog.
- ENVE states that most rear hubs, including ENVE's own, allow a complete freehub swap without the use of tools or re-dishing of the wheel.
- ENVE offers HG, Micro Spline, XD, XDR and Campagnolo freehub bodies across its own wheel lines, which establishes that Micro Spline and Campagnolo freehub bodies are fitted to hubs other than those makers' own.
- ENVE states that checking with the drivetrain or cassette manufacturer is the best confirmation of which freehub to pick.
- KMC states that its X12 12-speed chain is compatible with SRAM Eagle and Campagnolo 12-speed systems and is not compatible with SRAM T-Type, eTAP and Flattop.
- KMC publishes the X12 chain's size as 1/2" x 11/128", corresponding to the standard derailleur-chain pitch and the 9- to 12-speed inner width.
- All bicycle derailleur chains share a pitch of 1/2 inch (12.7 mm) regardless of speed count, and chains for 9- through 12-speed share an inner width of 11/128 inch (2.18 mm).
- Compiled outer widths by speed count: 7.0-7.3 mm at 8-speed, 6.5-6.7 mm at 9-speed, 5.84-6.1 mm at 10-speed, 5.46-5.74 mm at 11-speed, 5.25 mm for SRAM 12-speed MTB, 5.15 mm for Campagnolo 12-speed and 4.9 mm for Campagnolo Ekar 13-speed. The source does not state what the spreads represent.
- Shimano's document C-254 is titled "Compatibility between rear derailleur and cassette gear teeth [ROAD, Gravel, METREA]". It covers road, gravel and Metrea models only, contains no MTB derailleurs, and publishes compatibility marks against named cassette tooth ranges rather than numeric capacity values.
- Shimano's document C-433 is titled "Rear drivetrain compatibility [MTB, LIFESTYLE]" and publishes a numeric "Largest sprocket" constraint per MTB derailleur model and drivetrain configuration, for example "RD-M9250-GS RD-M8250-GS (45T ≤ Largest sprocket ≤ 45T for 1x12-speed)" and "RD-M9000-SGS RD-M8000-SGS (40T ≤ Largest sprocket ≤ 46T for 1x11-speed, 42T for 2x11-speed)".
- Shimano's compatibility document index lists C-731 (FREEHUB and cassette spline compatibility), C-649 (LINKGLIDE cassette and FREEHUB compatibility), C-817 (7-speed rear derailleur and FREEHUB compatibility), C-254 (road, gravel and Metrea rear derailleur and cassette) and C-433 (MTB and Lifestyle rear drivetrain).
- Shimano's MTB rear derailleur specification index lists models such as RD-M9100-GS, RD-M9100-SGS, RD-M8200-SGS, RD-M8100-GS, RD-M8100-SGS, RD-M8120-SGS and RD-M7100-SGS, and contains no road models.
- Shimano's road rear derailleur specification index lists models including RD-R8000-SS, RD-R8000-GS, RD-R7100, RD-R7000-SS, RD-R7000-GS, RD-R4000, RD-4700-SS, RD-4700-GS, RD-R3000-SS/GS and RD-R2000-SS/GS.
- Speed count alone does not establish compatibility between a cassette and a freehub body, or between a chain and a drivetrain.
- In an MTBR thread, a rider could not fit a worn 9-speed cassette onto a new hub of the same speed count. Replies attributed the problem to the cassette's condition and its steel spider against an aluminum freehub body, warned it would damage the body, and noted removal would be harder than installation. It was not a freehub-standard mismatch.