Putting 9 speed cassette on a 7 speed hub?!?

I have a set of 9 speed sora shifters that I'm to use to a build a bike, and they have been a massive pain from the get go, first I didn't have cable stops, then the cassette on my wheel was 7 speed. Someone told me that 7, 8 and 9 speed free hubs were the same length and I could just get a 9 speed cassette, but alas I know have a 9 speed cassette my freehub is not big enough for it.

I was wandering if I could just only put 7 gears on and not shift into the highest ones? I don't want my bike to be very nice necessarily, just functional by the end of march for as little money as possible.

is your hub a shimano one? if so, you have to check one thing: does your casette body have threads on the OUTside only? if this is the case, no.

if you have threads on the outside and inside too, it can be done. shimano changed the casette body length in the 7/8 transition era. 8sp=8/9/10 (10sp needs a 1mm spacer).

if your hub is the older 7sp UG (threded on the outside only) you can get a newer casette body (8sp HG) and fit it to your hub. there are a lot of interchangeable parts (eg. i fitted a HB6200 600 hub with a later XT casette so the GF could have 9speeds).

also, this thread belongs in mechanics and the problem must have been addressed quite a few times (as i wrote the same thing down in another thread a few weeks ago) :)

is your hub a shimano one? if so, you have to check one thing: does your casette body have threads on the OUTside only? if this is the case, no.

if you have threads on the outside and inside too, it can be done. shimano changed the casette body length in the 7/8 transition era. 8sp=8/9/10 (10sp needs a 1mm spacer).

if your hub is the older 7sp UG (threded on the outside only) you can get a newer casette body (8sp HG) and fit it to your hub. there are a lot of interchangeable parts (eg. i fitted a HB6200 600 hub with a later XT casette so the GF could have 9speeds).

also, this thread belongs in mechanics and the problem must have been addressed quite a few times (as i wrote the same thing down in another thread a few weeks ago) :)

essentially every 8-9 speed freehb body will work with 10spd cassettes (see, SH-1056, SH-6402) but if someone has a seven speed freehub body (which is alas, shorter) the only option to fit an 9spd cassette is to drop one cog. Then he'll have 8spd at the rear, but with 9spd spacing, so the setup will work with any 9spd shifter.

using a seven speed cassette with 9spd shifter is a pain. the indexing will be totally out of alignement after a few cliks. avoid it.

finding freehub bodies for older shimano hubs is not always easy, though I do believe that probably a new tiagra (4600) hub for 20 euros is sometimes cheaper than to get the desired fh body..