New Member
Nov 3, 2012
Hi there, anyone out there can help!
I've got an 8 speed lx cassette, for a 8/24 speed retro mountain bike I'm building. The rear wheel I have bought has come with a 9 speed xt cassette. Can I use the better cassette and just replace the removed (12t !!?) cog with a spacer or is this a no no?. or should I just stick with the lx cassette. The rest of the groupset is 739 shifters, etc.
Cheers NTT


Well-Known Member
Jul 23, 2005
[COLOR= rgb(24, 24, 24)]The [/COLOR]spacing[COLOR= rgb(24, 24, 24)] between the cogs of an 8-speed Cassette and of a 9-speed Cassette is [/COLOR][COLOR= rgb(255, 0, 0)]different [/COLOR][COLOR= rgb(24, 24, 24)]...[/COLOR]
[COLOR= rgb(24, 24, 24)]So, the [/COLOR]'official'[COLOR= rgb(24, 24, 24)] answer would be 'NO' ...[/COLOR] BUT[COLOR= rgb(24, 24, 24)], due to the Shimano's superior ramping which you will find on all their 9-speed-and-subsequent cogs ([/COLOR]or, later 8-speed/etc. Cassettes[COLOR= rgb(24, 24, 24)]), the 9-speed Cassette will probably work ([/COLOR]the 8-speed shifter will only find 8-of-the-9 cogs, BTW[COLOR= rgb(24, 24, 24)]), [/COLOR]as-is[COLOR= rgb(24, 24, 24)], but it may-or-may-not be a bit dodgy DEPENDING on how you adjust the rear derailleur's stops & cable ... [/COLOR]

  • [COLOR= rgb(24, 24, 24)]adjust the rear derailleur's Hi-Lo stops, as needed ...[/COLOR]

The GREATER problem may be with the chain's width ...

  • HOWEVER, if you swap to a 9-speed chain, then the front derailleur will have difficulty shifting the chain across all three chainrings -- NOT a good thing!

So, FWIW, I recommend that you simply save the the 9-speed Cassette for when you have a bike with a 9-speed drivetrain OR for when you decide you also want to change the shifters + front derailleur to 9-speed components.

[COLOR= rgb(24, 24, 24)] [/COLOR]