Bicycle Mechanics - Freewheel question

I have been out of the sport for a while and can't remember what I need... I just got a new set of wheels and need some cogs. I know there used to be free wheels and cassettes, but don't really remember. Anyway, I need a shimano compatable 8 speed _________. What do i ask for? I am planning on finding it on ebay and want to make sure I get the right thing. Thanks!

DD

Question?

Is you hub threaded or is there a splined ratcheting thingy (Freehub) that the cogs slide onto?

If you have a freehub, you need "an 8 - Speed Cassette".

L8R

New better stuff uses cassettes.Freewheels are still around too. If you hub is splined it takes a cassette, If it has big threads,it takes a screw on freewheel.you also need to match the number of cogs on the whatever to the number os speed in your index? shifters.

It is the second... I guess a free hub...

Look at the end of the small cogs on your hub. If there is a small lock-ring with arrows for lock and unlock, you have a freehub. If you dont have any cogs on the hub, can you see a splined tube which rotates ? That is a freehub design. You will need a chain whip and a lockring tool to replace the cogs. Time for a visit to your local bike shop ??

Park Tools has a good website to explain more.

It does not have any cogs on it, just the splined thingy. LBS's are old fashioned... I know just enough to be dangerous and what I don't know, I find out here:D . I just bought a sweet set of Rigida wheels with bladed spokes from a buddy. I got a heck of a deal and for the first time will have something with radial laced spokes. It is amazing how much this stuff has changed in a short period of time... I remember when radial lacing was "new".

Next question... will I need a new chain? I am going from 7 to 8... baby steps, I know!

If you are putting on a new cassette,start with a new chain too.Your shifters match the number of cogs you are going to have on the rear?????

Yeah, I just scored some sti shifters from ebay. I installed them with my 7 speed stuff, the work fine, just have an extra 'click'. I really am fine with 7 speeds, raced for years on 6, even with junior restricted gears... is one more really worth it?

Originally posted by tex
... for the first time will have something with radial laced spokes. It is amazing how much this stuff has changed in a short period of time... I remember when radial lacing was "new".

Next question... will I need a new chain? I am going from 7 to 8... baby steps, I know!

I built a radial-laced front wheel in the early 1970s, but I still think cross-laced wheels are more reliable, because the crossed spokes spread any sideward load on the rim. Radial lacing is OK on the left side of a rear wheel (Sheldon has a pretty good article on this), but I have actually seen some factory wheels with radial-laced driveside spokes, which makes no engineering sense whatsoever. I'll stick with what works: 32 or more spokes, in a 3X pattern.

You do not necessarily need a new chain, unless your 8-speed was built up with 9-speed cogs and spacers. However, if your chain has stretched more than 1/16" per 24 half-links, you do need a new chain.

It's been some time since I upgraded to 8spd from 7 but as I recall you need to extend the axle on the cassette side as the 8 is wider than the 7.
I think I managed to scrounge some axle spacers to increase the axle length but this does push the centre of the wheel over slightly off centre and the axle requires a little more room between the dropouts. (Should really recentre the wheel)
If its an old frame it might be a good idea to get the stays coldset by the LBS for 130mm
I would recommend going for 8 speed it gives a much more even spread of gear ratios
:)