One spacer or two...?

San Marzano

Hi

I’ve just swapped cassettes (both 10 speed) on a Mavic Ksyrium SL wheel.

I seem to have two spacers – one quite thick and the other much thinner. I can’t remember where they both came from 

It’s a simple question – do I need to fit both spacers at the back of the cassette?

Thanks

The Rookie

You only need enough that the locknut clamps the cassette in place without moving on the freehub, fit as little spacer as is needed to achieve that!

sungod

mavic sram/shimano hub always use the thick spacer with 10-speed cassette

plus the thin spacer for most shimano cassettes, but not for tiagra

no thin spacer for sram cassettes

San Marzano

Thanks chaps, I thought that it needed both and set it up that way but just wanted to be sure.

Freewheeling down a long descent last night – I started backpedalling slightly and there was a grinding/rubbing noise which stopped as I started pedalling forwards. It sounded very much like to spacers could be rubbing against each other / spinning round whilst the freehub was stationary???????

sungod

won't be that, nothing will rotate on the freehub body itself, cassette etc. are all splined

presumably you were in the smallest sprocket, might've been the slack chain hitting the chainstay

The Rookie

As he says, not that as a little logical thought tells you.

If its only when back pedalling and not freewheeling it sounds like the chain slack or slightly to long so it's rubbing on itself.

San Marzano

Definitely a grinding noise, not chain slapping / knocking on the chainstay....

It only comes on when travelling at speed and back pedalling. Once you start pedalling forwards it stops but can easily be brought on again by slowly rotating the cranks backwards................

Thanks all for your advice though, I will borrow tool and check chain length tonight.