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Converting 7 Speed into 1 speed(5 posts)

Converting 7 Speed into 1 speedwarriorcharge
Jun 18, 2002 9:13 AM
can i somehow convert an old 7 speed cassette wheel to use a single speed(i dont care how it looks)
re: Converting 7 Speed into 1 speedbrider
Jun 18, 2002 9:23 AM
Single speed -- yes. Fixie -- no. Use stacks of spacers to get the right chain line, then tighten the cassette HARD. You'll only have one cogs worth of splines engaging the cassette body, so the potential for stripping is pretty high. A better solution would be to get a cheap thread-on hub and a BMX freewheel, then re-space the hub to get the right chainline, and lace to a bombproof rim.
i can think of one wayczardonic
Jun 18, 2002 9:33 AM
I am assuming that you are stuck using the whole cassette on the wheel for some reason. If so, you would have to pick the best cog, and then fiddle with spacers on the chainring bolts and/or BB's with different spindle lengths to get a good chainline between your chosen cog and the chainring.

Chainline will be particularly important if you still have neighboring cogs, because anything less than straight may cause the chain to try and shift. If it goes to a larger cog, it could break, or do other damage.

Chain tension will also be important to preventing unwanted shifting. You could use the old rear derailer, or buy a tensioner.

Then again, for the money you could spend on a tensioner, you could go a fair way toward buying a cheap but functional single speed hub. I converted an old 10 speed to a fixed gear using Suzue track hubs (the rear can be flipped and used with a single speed freewheel). Excel sells the rear hub for $27. You would still need spokes to re-build the wheel, but you would have a much better selection of gears.

Folks on the Single Speed board at MTBR may have more ideas, or experience with the hub you are working with.
if it's really old it's easierlaffeaux
Jun 18, 2002 9:45 AM
If the larger cogs are integrated in with the spider it can be difficult to select the cog that you need (unless you're happy with one of the smaller cogs. If your cassette is older and has no spider, the casette will pull apart completely. Use the internal spacers (plus you'll need a few extras) to fill up the extra room on the hub. Place the one cog between the spacers where it gives you the best chain line.

I just did this on an old MTB. It looks like crap but seems to work.
spacersoff roadie
Jun 18, 2002 12:14 PM
Like others pointed out, all that is needed is to move the desired cog in-line with your chainring via some spacers. Your 7 speed probably doesn't have a spider, but you if it does, you can still use some of the cogs on a spider- you just mount the whole spider so the desired cog lines up. You could even pull the other cogs off the spider, if you wanted.

Your spacers don't HAVE to be cassette spacers. A properly cut piece of PVC pipe will do the trick, if need be.

Its a real improvement if instead of using a cog (w/ or w/out spider) from you existing cassette, you get a Shimano DX Cog or a King Cog. They are cheap ($10 or $20), and fit on standard Shimano freehubs. They are specifically designed for singlespeed freehubs (designed BMX or MTB), made from a thicker metal (so they don't dig into the freehub body and can take more abuse) and have taller, non-shifting teeth (so the chain won't come off as easily).

That's as far as a lot of singlespeed conversions go, and its actually a very good option.