I need to install a 7-speed cassette on a Hyperglide freehub. This cassette is narrower than the freehub's spline height (meant to accommodate 9 and 10-speed cassettes). I also bought an additional spacer which was supposed to take up the slack:

Cassette spacer

When the parts had arrived, I discovered that the freehub's body was designed for 11-speed road Hyperglide. That is, it was even longer. The spacer that I had already bought was not enough to compensate for the height difference.

So, I need to use a second spacer to convert it full way from 11 speed road → 10 speed MTB → 7 speed, and then finally fit my cassette.

I have a lot of spare plastic BB spacers meant to be used with 68mm bottom brackets shells to accommodate 73 mm BBs.

BB spacer

Such a spacer fits on the freehub body. Its height is close enough to what I could have if I used an "official" spacer. It does not have splines to prevent it from rotating.

Would this arrangement (two plastic spacers) reliably work? To clarify, I am offsetting the whole cassette, not individual cogs on it.

  • 1
    The BB spacers are likely to all be 2.5mm. if you have a spacer for a 7s cassette on a MTB 11s freehub, that can be up to 3.45mm. To fit a 7s cassette on a road 11s freehub requires between 3.95 and 5.25 mm of spacers. So if you have the wide 3.45mm spacer and use a 2.5mm BB spacer, you're over by 0.7mm. Watch that doesn't negatively affect the mounting
    – Jeff
    Feb 26, 2022 at 10:55

1 Answer 1


Yes, it will work to use the plastic spacers. If they are not pressed against a flat surface however, they can warp and potentially crack. The metal spacers are better. You can also use individual sprockets from an old cassette as spacers. Anything 12 tooth or larger will slide all the way on and give you lost of options to get the spacing just right with the combination of different materials you have to hand.

My best suggestion is to use an official 1.8mm spacer to go from 11sp to 8/9/10 then use a 12t sprocket from a 7-or-8-speed at the back of the cassette to get down from 8/9/10 to 7.

  • Good point about stress risers with a no-splined plastic spacer. I need to sift through my "too worn to use, too good to throw away" box(es) for internal cassette spacers. Might even find a correct spacer unused in a past build. Feb 26, 2022 at 17:29

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