I was hoping that someone could provide me with the precise Shimano road-bike 8, 9, and 10 speed sizes for the following:

  1. Cassette Spacer Width
  2. Cog/Tooth Width
  3. Maximum Chain Width

1 Answer 1


I think these may be what you're looking for. FYI, a lot of this information is available with a little searching. Depending on what exactly you are looking for, you might want to look up a document for a specific cassette as the numbers might be slightly different.

Spacer widths (From Shimano tech docs)

  • 8 Spd: 3.00mm
  • 9 Spd: 2.56mm
  • 10 Spd: 2.35mm (1.0mm for lower spacer)

Cog/Tooth Width (From Sheldon Brown)

  • 8 Spd: 1.8mm
  • 9 Spd: 1.78mm
  • 10 Spd: 1.6mm

Chain widths (From wikipedia)*

  • 8 speed - 7.1mm (all brands)
  • 9 speed - 6.6 to 6.8mm (all brands)
  • 10 speed - 6.2mm (Shimano, Campagnolo)
  • 10 speed(Narrow, Direction) - 5.88mm (Shimano CN-5700,CN-6700,CN-7900)

*These chain widths are the standard widths, which I assume are recommended. I wouldn't go wider, but a narrower chain will probably work as some chains are cross-compatible.

  • 3
    +1 for being generous enough to provide an answer despite the fact that op could have easily have found the answer through Google.
    – PeteH
    Commented Aug 12, 2013 at 21:54
  • 1
    @PeteH Google won't have it nicely in one place like this. Well, it probably does now, if it points to this question!
    – Kaz
    Commented Jul 22, 2016 at 16:11
  • @Kaz People have maintained these lists on web pages for years!
    – PeteH
    Commented Jul 22, 2016 at 16:23
  • @PeteH, By the way, this morning I used a caliper gauge to measure, down to the micron, a KMC Z51 (which was labelled as a 6-7-8 speed), as well as a SRAM PC-850 (labeled as just 8 speed on the packaging). The both measured quite exactly 7.65 mm, not 7.1, at the widest girth. I wonder whose 8 speed chains actually measure 7.1.
    – Kaz
    Commented Jul 22, 2016 at 20:15
  • 2
    Pitty the OP didn't ask for overall cassette widths too.
    – david1024
    Commented Oct 20, 2016 at 18:26

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