replacing 7 and 8 speed shiman freehubs

steve68

I have an old Dawes giro 400 with shimano 7 speed sti. About a year ago I needed to replace the rear wheel but my local bike shop only had wheels with 8 speed hubs and free hubs. They gave me a 3mm spacer to fit my 7 speed cassette onto the hub, but it has always felty very loose, and is playing havoc with my indexing, even when tightened to 40nm.
I still have the old broken wheel, and tried today to swap the freehubs over. I removed the 7 speed freehub from the old wheel with a 10mm Allen key, but when I tried to do the same with the 'new' wheel with the 8 speed freehub, there was nothing for the allen key to turn.
How are 8 speed freehubs fastened onto the wheel hub. Is it usually different? Am I just better off getting the broken spokes on the old wheel repaired even though the rim is 10 yrs old?

nicklouse

the spacer should be 4,5mm thick that could be the problem.

they fit the same way. but 8/9speed hubs are a little wider than the 7spd.

was you frame cold set for the wider hub or was the hub just squeezed in?

steve68

thanks for the reply. The frame was not adjusted for the new wheel, so I guess the wheel was squeezed into the frame. Will try my LBC today (a mountain bike shop) for any spokes to repair the old worn out rim.

maddog 2

It's not that 8spd hubs are wider, it's that the freehub on a 8spd hub is wider and thus takes up a bigger proportion of the overall width of the hub.

Hence, a 7spd wheel and a 8spd wheel are the same width.

but if you fit a 8spd freehub to a 7spd wheel you'll need to re-cone and re-dish the wheel.

the solution is to get the right washer, or an extra washer, so the cassette fits properly. A decent LBS should have (he says speculatively).

If it's a Shimano 8spd hub then the freehub is connected by a 10mm allen key, as you suggest. If the hub is not Shimano then it could be connected in any number of ways.