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Swapping a Cassette at Home, Without Guesswork

The bench · September 1, 2026 · 7 min read

I am a hobbyist shop hand who likes jobs that end with a quiet drivetrain.

A cassette swap is one of the shortest jobs on the bench. Wheel out, lockring off, cogs off, new cogs on, lockring back. The hard part is not the wrench work. The hard part is knowing, before you order anything, which cassette your rear wheel and your rear derailleur will accept. That answer comes from three measurements, and if one of them is not on file, the shop says so instead of selling you a part.

Three numbers decide the part

Every cassette page in the shop carries the same three requirements: the freehub body it splines onto, the number of rear speeds it is cut for, and the largest cog your rear derailleur has to be able to wrap. Match all three and the job is mechanical. Miss one and the cassette either will not slide on, will not index, or will jam the derailleur into the spokes. Those are the rows to read before you read anything about tooth counts and range.

Requires — Freehub bodyShimano HG, 8/9/10-speed body (also 11/12-speed MTB HG cassettes)
Requires — Rear speeds9 speeds
Requires — Rear derailleur max cog≥ 46 t
Manufacturer part numberCS-H093 11-46
Requires — Freehub bodyShimano Micro Spline (12-speed MTB)
Requires — Rear speeds12 speeds
Requires — Rear derailleur max cog≥ 51 t
Manufacturer part numberCS-M7100-12 10-51
Requires — Freehub bodyShimano HG, 11-speed road body (+1.85 mm)
Requires — Rear speeds11 speeds
Requires — Rear derailleur max cog≥ 36 t
Manufacturer part numberCS-PG-1130-A1 11-36

The bench procedure

You need a cassette lockring tool that matches your lockring pattern, a wrench or adjustable spanner to drive it, a chain whip, a rag, and a light grease or anti-seize for the freehub threads. A torque wrench is the right way to finish, but we do not publish a torque figure here because we have no manufacturer sheet on file for it — read the number stamped on your own lockring or printed in the cassette's instruction sheet.

Removing and fitting a rear cassette

  1. Get the wheel out and clean Shift to the smallest cog, release the brake if it is rim brake, and remove the rear wheel. Pull the thru-axle or quick release. Wipe the cogs and the freehub area so grit does not travel into the threads. If your hub uses a Center Lock rotor, leave the rotor alone; it is not in the way of this job.
  2. Break the lockring Seat the lockring tool fully into the splines. If the tool has a guide pin, thread the axle nut or skewer over it to hold it square — a tool that skips will chew the lockring. Wrap the chain whip around a large cog so it drives the cassette clockwise, then turn the lockring counter-clockwise. It will crack loudly. That noise is the retaining teeth, not damage.
  3. Lift the cogs off in order Slide the lockring off, then draw the cassette straight off the freehub body. Loose sprockets and spacers may separate; lay them on the bench in the order they came off, facing the same way. Note the widest spline groove on the body — the cassette only goes back one way.
  4. Inspect before you commit Look at the freehub splines for gouging. Look at the cogs you removed: shark-fin teeth mean a worn chain has been at work, and a fresh cassette on a worn chain will skip. Check chain wear now, while the wheel is out and everything is easy to reach.
  5. Fit the new cassette dry and true Wipe a thin film of grease on the freehub threads only, not on the cog faces. Align the wide spline and push the cassette on. Confirm every spacer sits where the manufacturer's sheet shows it — a missing spacer is the usual cause of a cassette that will not index or a lockring that bottoms out early.
  6. Torque, refit, index Thread the lockring by hand first to be sure it is not cross-threaded, then bring it up with the tool to the torque marked on the ring. Refit the wheel, close the axle, and run through the gears on a stand. Small barrel adjuster corrections, an eighth of a turn at a time, are normal after a swap. Chain and derailleur limits stay as they were unless you changed the largest cog.

The wrench work takes minutes. The freehub body decides whether the job is possible at all.

The cassette pages the shop lists

microSHIFT ADVENT H-Series 9-speed cassette 11-46T

Shimano SLX CS-M7100-12 cassette 10-51T, 12-speed

SRAM PG-1130 cassette 11-36T, 11-speed

A worked example: the gravel bike on the stand

Here is what the projection looks like against a real bike in the fleet. Note first that no bike in our fleet is fully verified yet — some rows are derived from a single sheet, and where a row is missing we say it is missing.

Freehub bodyShimano HG, 11-speed road body (+1.85 mm)
Rear speeds12 speeds
Chain standard12-speed HG+ / Eagle (5.25 mm)
Rear axle spacingThru-axle, 142 × 12 mm
Shift actuationMechanical (cable)

Canyon Grail CF SL 7 (2025)

The microSHIFT ADVENT H-Series 9-speed cassette 11-46T does not fit the Canyon Grail CF SL 7 (2025): the rear speed count on the bike does not match what the cassette is cut for, and the bike's rear derailleur maximum cog is not on file at all. The Shimano SLX CS-M7100-12 cassette 10-51T, 12-speed does not fit the Canyon Grail CF SL 7 (2025) either — the freehub standard is different, and again the maximum cog is missing from the bike's record. The SRAM PG-1130 cassette 11-36T, 11-speed does not fit the Canyon Grail CF SL 7 (2025): the freehub matches, but the speed count does not, and the maximum cog row is still blank.

Cassette — Canyon Grail CF SL 7 (2025)

Can I put a wider-range cassette on without changing anything else?
Only if your rear derailleur's maximum cog rating covers the largest sprocket and your chain is long enough. Both are separate checks. If the derailleur's rating is not on file, that is an unknown and we will not call it a fit.
Do I need a chain whip, or can I hold the cogs by hand?
You need a chain whip, or a cassette-holding tool of some kind. The freehub ratchet spins freely in the loosening direction, so without a whip you are just turning the wheel.
Should I replace the chain at the same time?
If the old chain is worn, yes. New cogs meshed with a stretched chain will skip under load, and you will end up doing the job twice.
Can a spacer make a mountain-bike cassette fit a road freehub?
A spacer only ever addresses body width, and only for cassettes designed for that body. It cannot change a spline pattern. Micro Spline and HG are different standards, and no spacer bridges them.
Why do you say no bike here is fully verified?
A fact is derived when one manufacturer or standards sheet states it, and verified when two independent publishers agree. None of our fleet records has hit that second threshold across the board yet. We would rather say that out loud than dress a single source up as certainty.

What to hold on to

  • Read three rows before you buy: freehub body, rear speeds, and the derailleur's maximum cog.
  • The tools are a lockring tool, a driver, and a chain whip. Grease the threads, not the cog faces.
  • Lay the sprockets and spacers out in order; a missing spacer is the classic cause of a swap that will not index.
  • All three cassettes the shop lists are projected not to fit the Canyon Grail CF SL 7 (2025), each for its own reason.
  • A blank row means unknown, and unknown means we stop. Give us the sheet and we will finish the answer.

More in the Journal

  • What We Still Don't Know About the Grail CF SL 7

    The Canyon Grail CF SL 7 (2025) sits in our fleet with one source behind each fact and no second publisher agreeing yet. Here is what that means, which answers still stand, which ones wait, and what would change them.

  • SRAM DUB bottom brackets, sorted by shell

    Five SRAM DUB bottom brackets sit in the drawer. They all hand the crank the same spindle interface; what separates them is the frame shell they need. Here is each one by its numbers, plus the one projected verdict we have on file against a bike in the fleet.

  • The Cassette Shelf, Counted Cog by Cog

    Five cassettes are on file in the archive: one nine-speed microSHIFT, one twelve-speed Shimano, and three SRAM eleven-speed options. This guide lays out the three numbers that separate them — freehub body, rear speeds, and the smallest rear derailleur capacity they demand — and says plainly which bike in the fleet they do and do not fit.

  • Why your 11-speed chain fits — and the 12-speed one does not

    Chain compatibility comes down to one standard most boxes print as a speed count: the chain width. Here it is for the two KMC chains people ask about most, and what it means on an 11-speed and on a 12-speed bike from the fleet.

  • The Giant Escape 3, As Far As Our Paper Goes

    A plain accounting of the Giant Escape 3 (2024): the measurements we have on file, the ones we do not, the three regions worth reading before you buy, and four listed parts with their projected verdicts.

  • Rear Wheel of the Giant Fathom 29 2: What Bolts On

    A region guide to the rear wheel of the Giant Fathom 29 2 (2022): the cited frame and wheel facts we hold, the two Maxxis parts projected to fit, why each verdict lands where it does, and the measurements that are still missing from the file.

  • The Glory Advanced Is on File, Not Yet Verified

    Every fact we hold on the Giant Glory Advanced (2025) comes from a single cited source. That is enough to answer some questions and not enough to answer others. Here is exactly which is which, and what would move a line from unknown to answered.

  • Setting Up a Rear Derailleur on the Bench at Home

    A plain bench procedure for hanging, limiting, indexing and clutch-checking a rear derailleur at home, plus the three rear derailleurs the shop lists and how they read against the Canyon Grail CF SL 7 (2025).

  • The e12 chain and the Grail: a clean match on the drivetrain

    The KMC e12 e-bike chain, 12-speed fits the Canyon Grail CF SL 7 (2025). The chain standard on the bike's sheet matches the chain standard the part requires. Here is the reasoning, the rows behind it, and what happens when you bring an older chain to the same drivetrain.

  • The KMC X10, and the one thing it asks of your bike

    The KMC X10 chain, 10-speed has a single requirement: a 10-speed drivetrain. We read the spec rows, then check it against the two bikes on file with the same chain standard — the Giant Fathom 29 2 (2022) and the Kona Sutra (2025). Both come back as fits, on derived facts.

  • The X9 and the Roam: one chain, one answer

    The KMC X9 chain, 9-speed fits the Giant Roam 2 Disc (2021). The chain standard on the bike matches the chain standard the part asks for, and both facts are on file. Here is the reasoning, the spec rows behind it, and the chain that does not fit.

  • Rotor size is a safety question, not a taste

    A bigger rotor brakes harder. It also loads the fork mount beyond what it was tested for when it exceeds the fork maximum. Here is why a rotor reads "unknown" on a single-sourced bike, "does not fit" when the interface is wrong, and "unknown — safety-critical" when the maximum is not on file.

  • The 1.85 mm spacer: the cassette that confuses everyone

    An 8/9/10-speed cassette on an 11-speed road freehub: why there is a gap, why a 1.85 mm ring fills it, how the resolver treats that ring — and why the page can still say "unknown" after the freehub question is settled.

  • DUB: One Spindle, Four Shells

    SRAM DUB is a crank spindle standard measured at 28.99 mm. Here is what that number does mechanically, which bottom brackets in our archive carry it, and why the shell in your frame — not the spindle — decides what you can buy.

  • What "unknown" means in this shop

    A bike we have not verified stays on the floor with a sign on it, not in the back room. Here is what that sign says, with the Brompton C Line as the live example, and why we would rather lose the sale than guess.

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