Can I use BSA bottom bracket's plastic spacer as a cassette spacer?

Question

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:

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.

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.

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.