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8 Speed Cogs on 10 Speed Cassette

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8 Speed Cogs on 10 Speed Cassette

Old 10-08-20, 04:36 AM
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8 Speed Cogs on 10 Speed Cassette

I have a bunch of both 8 speed and 10 speed loose cogs mixed together in a ziplock bag. I can't really tell which are which.

QUESTION: Can these cogs be installed on either type of cassette, if the proper spacers are used, and the tooth limits for adjacent cogs observed? TYIA.
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Old 10-08-20, 05:42 AM
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Sure. Do it all the time.
There are minor differences in thickness between different 'speeds' of HG cogs, but they will still work reasonably well together.
Shimano does index the various shifting gates in standard issue cassettes for optimum performance but even less than optimum is still very, very good in my opinion.
You may find it easier to use a 10 speed first cog (with spacer built in) with a 10 speed cassette and with an additional thin spacer for an 8 speed cassette.
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Old 10-08-20, 08:33 AM
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If you have a micrometer or a decent caliper you can sort them out. Shimano 8-speed cogs are 1.8 mm (0.071") thick and Shimano 10-speed cogs are 1.6 mm (0.063") thick.
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Old 10-08-20, 09:03 AM
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As others said, measure the thickness, or at least set the cogs on a flat surface and figure out which are which.

I tend to nit-pick cog spacing. With 10 speed 1.6mm cogs, I’d use 3.15mm spacers from a 7 speed cassette to get close to the 8 speed 4.8mm center to center spacing. Center to center distance is what is important.

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Old 10-08-20, 01:42 PM
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Scroll down just a tiny bit-
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Old 10-08-20, 02:10 PM
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Great, thank you Bill! I knew the info was out there someplace on the web, but it's gotten very difficult lately to find specific things like this, without slogging through 20 pages of irrelevant search results.

I've taken a screenshot of this and will print it out and put in my toolbox, for future reference.
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