8spd mtb cassette on 7spd freehub?

Sheldon Brown has a lot of stuff on his site about cassettes sheldonbrown.comk7.htmlOpen ↗

Spacing and cog width is covered for many options.

Regards, Maurie
=================================

hippy said:

Will an 8 speed Acera/Alivio cassette fit onto a 7 speed AceraX freehub?
i.e. is it not too wide?

Forgetting the width for a second, will a single cog from the 8spd cassette fit onto the freehub?
i.e. Do the "bumps and grooves" on the inside of the 8spd cog match those on the outside of the
7spd freehub?

Has the bottom bracket size changed from the AceraX groupset to the Acera/Alivio groupset? I think
~1996 Shimano versus 2000.

cheers hippy

hippy said:

Will an 8 speed Acera/Alivio cassette fit onto a 7 speed AceraX freehub?
i.e. is it not too wide?

No, it's too wide, so it won't fit. Eight sprockets from a 9-speed cassette will fit perfectly, but
an eight speed cassette will overhang the end of the freehub. Seven eighths of an 8-speed cassette
will also fit, but you may need to use a thin spacer to allow the lockring to engage properly.

Quoted message said:

Forgetting the width for a second, will a single cog from the 8spd cassette fit onto the freehub?
i.e. Do the "bumps and grooves" on the inside of the 8spd cog match those on the outside of the
7spd freehub?

Yes. The spline pattern is common to nearly all Shimano hubs made in the last dozen years, 7-, 8-,
or 9-speed.

Quoted message said:

Has the bottom bracket size changed from the AceraX groupset to the Acera/Alivio groupset? I think
~1996 Shimano versus 2000.

Sorry, I don't know.

James Thomson

Check out Sheldon Brown pages, you may be able to transplant the freehub body to an eight, you may also need to adjust the frame for the extra clearance. I transplanted a 7speed Uniglide body for 7 speed hyperglide one recently. Not a difficult job for one who is happy weilding large wrenches. I have often replaced single sprockets on my 1989 7-speed cassette with new ones which I presume are aimed at 8 or nine speed cassettes. I intend to do what the other poster said, that is fit 8 of the nine sprockets from a 9 speed cassette, use a nine speed chain and shifter. I have already checked and 8 from 9 will fit onto a 7 speed body and my frame (126mm drop out spacing) will accommodate it. I have the advantage then of cross compatibilty with my 1999 Ultegra 9 speed bike.