Shimano CS-M8100 Cassette
What the checker says94will not fit
Run variant by variant through the e-MTB builder’s own engine. Every sentence below is the checker’s, unedited. Nothing here says this part fits your bike; it says what it does and does not fit among the parts we hold.
Checked against 458 verified e-MTB parts in this catalog. 335 produced no finding of any kind; that is CS-M8100 10-45 (2019). CS-M8100 10-51 (2019) clears 330. Each variant produces 50 to 78 distinct errors and 0 distinct warnings.
Will not fit
- Will not fiterror · Rear WheelFreehub mismatch: Shimano CS-M8100 10-45 needs a MicroSpline freehub, but Rear wheel has XD. On 23 of the 47 verified rear wheels in this catalog. Applies to 1 of 2 variants.
- Will not fiterror · Rear WheelFreehub mismatch: Shimano CS-M8100 10-51 needs a MicroSpline freehub, but Rear wheel has XD. On 23 of the 47 verified rear wheels in this catalog. Applies to 1 of 2 variants.
- Will not fiterror · Rear DerailleurDrivetrain mismatch: Derailleur = shimano-linkglide, Cassette = shimano-12. Shifter, derailleur and cassette must be one system. On 21 of the 74 verified rear derailleurs in this catalog. Applies to all 2 variants.
- Will not fiterror · Rear DerailleurSpeed mismatch: Derailleur 11s, Cassette 12s. Shifter, derailleur and cassette must be the same speed count. On 15 of the 74 verified rear derailleurs in this catalog. Applies to all 2 variants.
- Will not fiterror · Rear DerailleurDrivetrain mismatch: Derailleur = sram-eagle, Cassette = shimano-12. Shifter, derailleur and cassette must be one system. On 12 of the 74 verified rear derailleurs in this catalog. Applies to all 2 variants.
- Will not fiterror · ShifterDrivetrain mismatch: Shifter = shimano-linkglide, Cassette = shimano-12. Shifter, derailleur and cassette must be one system. On 11 of the 53 verified shifters in this catalog. Applies to all 2 variants.
- Will not fiterror · Rear WheelFreehub mismatch: Shimano CS-M8100 10-45 needs a MicroSpline freehub, but Rear wheel has HG. On 11 of the 47 verified rear wheels in this catalog. Applies to 1 of 2 variants.
- Will not fiterror · Rear WheelFreehub mismatch: Shimano CS-M8100 10-51 needs a MicroSpline freehub, but Rear wheel has HG. On 11 of the 47 verified rear wheels in this catalog. Applies to 1 of 2 variants.
Emtb cassette capacity, Rear Derailleur. 56 more findings from the same check, on up to 1 of the 74 verified rear derailleurs each.
Emtb drivetrain system, Shifter. 11 more findings from the same check, on up to 6 of the 53 verified shifters each.
Emtb drivetrain system, Rear Derailleur. 10 more findings from the same check, on up to 7 of the 74 verified rear derailleurs each.
Emtb drivetrain speeds, Shifter. 5 more findings from the same check, on up to 10 of the 53 verified shifters each.
Emtb drivetrain speeds, Rear Derailleur. 4 more findings from the same check, on up to 10 of the 74 verified rear derailleurs each.
Open a variant in the builder to see the ones that apply to your own parts.
$185.00 MSRP·461 to 470 g
What the maker states
- Speeds
- 12-speed (rear index count the maker rates it for)
- System
- Drivetrain system Shimano 12-speed
- Freehub
- / driver Shimano Micro Spline
- Minimum cog
- Smallest cog 10 teeth
- Maximum cog
- Largest cog 45 teeth (on 1 of 2 variants); Largest cog 51 teeth (on 1 of 2 variants)
A value shown as a set or a range differs between this model’s variants and is never one variant’s spec.
2 verified variants
| Variant | Maximum cog | Price (MSRP) | Weight | Source | Last checked | Build |
|---|---|---|---|---|---|---|
| CS-M8100 10-51 (2019) | Largest cog 51 teeth | $185.00 | 470 g | maker’s page | 2026-06-22 | Build with this |
| CS-M8100 10-45 (2019) | Largest cog 45 teeth | $185.00 | 461 g | maker’s page | 2026-08-15 | Build with this |
The rest of what the maker states1 not published
1 further field the checker looks for is not published by Shimano, so we leave it blank rather than estimate it, and that check stays silent on this cassette. It is e approved. Each is recorded as “not stated by the maker (not checked)”.
Source: each variant links the maker’s own page in the table above. Last checked 2026-06-22 to 2026-08-15.
Checked against
The checker ran this model against every verified part below that it has a slot for, the same way it checks a build in the builder. What follows is the verdict it actually produced for that specific pairing — not a recommendation, and not a guarantee any of these parts fits your own bike.
- 9point8 Fall Line 30.9 / 125mm (INLINE) (Dropper Post) No conflicts found
- BikeYoke Divine 2.0 Dropper Post 31.6 / 125mm (Dropper Post) No conflicts found
- BikeYoke Divine SL Dropper Post 30.9 / 80mm (Dropper Post) No conflicts found
- BikeYoke Divine SL Rascal Dropper Post 30.9 / 80mm (Dropper Post) No conflicts found
- BikeYoke Revive 3.0 Dropper Post 30.9 / 125mm (Dropper Post) No conflicts found
- BikeYoke Revive Max 3.0 (34.9) Silver Ltd. Dropper Post 34.9 / 125mm (Dropper Post) No conflicts found
6 of 245 counterparts with a page of their own that the checker actually probed this model against, in alphabetical order by brand and model — never by price, popularity or the verdict itself.