7 speed cassette on a 9 speed hub - possible?

[severnthheathen]

I'm starting a build and before I hit the usual snags I thought I'd seek some expert advice on here. I have some STX-RC 7 speed shifters/brake levers that I want to use with a 7 speed cassette. I want to put the 7 speed cassette on a nice wheel that is built with an XT 9 speed hub. The back end is spaced 135 mm OLD. Any probs so far??

Then I want to fit an STX-RC chainset that specifies an IG chain. I read on here that a KMC X9 chain would run ok with this arrangement and I'd prefer to do this as they are easily sourced.

Does anyone see any snags with my intended drivetrain solution?

 

[Raging_Bulls]

Re:

If I'm not mistaken, 8, 9 and 10-speed use the same freehub. The 7-speed freehub is a little shorter.
To put a 7-speed cassette on a longer freehub, people generally put a spacer on the freehub before putting the cassette on there.

According to this auction it's a 4mm spacer.
http://www.ebay.co.uk/itm/7-Speed-Bike- ... SwbYZXf-ZY

I have a 7 speed cassette on an 8 speed freehub, not sure how thick my spacer is, but I think it was thinner than 4mm. (EDIT : Yup, just looked at the bike and it looks like 2.5mm at first glance)
Just put the cassette on the freehub, screw in the nut and see how much play there is. Get a spacer that's 0.5 to 1mm thicker than that and you should be good.

 

[rogerzilla]

Re:

There are 3mm spacers sold for this purpose. Look on the Bay of Thieves.

 

[hamster]

An old spacer robbed from an 8 speed cassette does the job perfectly.

 

[patersondj]

Re:

check the splines in the cassette fit on the hub drive... some seven speeds i think had a different spline. uni glide or hyper glide , i think.. but spacers for the win old cassette is cheaper than thief bay, free i tells you FREE..... :facepalm:

 

[hamster]

The spline was different for 6 speed, which was UG. 7 speed is all the same.