running an 8spd casette on a 7spd freehub?

[456_rich]

I bought some wheels sold as 8spd. When they turned up I realised they have a 7spd freehub. As I was keen to get out on my new bike I removed the second sprocket (the 13T) on my 8spd casette and indexed my thumb shifter to 7spd. Now the gears all work when the bikes on the stand but as soon as I ride the chain slips and jumps horrendously.

Is this bodge possible? or is 7spd totally different spacing to 8spd?

 

[legrandefromage]

the cassette may be worn regardless of cassette size.

anyway, if you change the freewheel to an 8spd, get the wheel redished and play about with axle spacing, it will all work.

just be prepared to get greasy one damp afternoon...

 

[Martin]

Maybe mech hanger is bend? Or like said above, worn cassette?

It should work....maybe not 100% perfect but it should be ok.

 

[BoyBurning]

be prepared to get greasy one damp afternoon...

LG, you dirty dawg...

Stop it boy - you bad!

 

[456_rich]

Sorry should have said new chain and cassette. I suppose the mech cage could be bent but not by much. Will have a look tonight.

 

[Andy R]

8 speed is closer spacing than 7 speed - I've successfully used 8 speed shifters with a 7 speed cassette but never the other way around like you're trying to do.
Presumably every shift will be slightly "over shifted" and the chain will attempt to climb to the next lowest gear. I imagine it might be worse on downshifts than when changing up?

 

[Loki]

You can run 8 gears of nine on 7 speed hub and use nine speed shifter with the last click limited out. Use a 9 speed chain also.
http://sheldonbrown.com/k7.html#897

scowl down to 8 of 9 on 7

 

[456_rich]

Just been fetling feel really stupid all it was, was the chain rings had worn out! So fitted new rings and it's silky smoothe now.

 

[legrandefromage]

Just been fetling feel really stupid all it was, was the chain rings had worn out! So fitted new rings and it's silky smoothe now.

ha!