Bicycle Mechanics - Single Speed Help

Ok i have an old bike all torn apart and want to make it a single speed just to ride for fun and to beat on. Its got a 6 speed rear cassete and crankset with 3 rings. i was just thinking i could leave it 3 in the front and take the front deraler off. But for the back can i just take the cassete of and apart and use one of the gears and the spacers to make it one in the back.

If that won't work or if theres a better way to do it with out spending alot of money i would love to hear about those to.

Thanks

Yep - run the chain on the middle ring on the front, and if you truly have a cassette, you may have to buy spacers to displace the cogs you leave off. Or leave the cassette intact, but move your chosen cog into the chainline.

From $ to $$$,

If you have no room in the dropout to take up slack, you can either find the magic sweet spot for chain length + cog size + chainring = no slack, use the derailleur to tension the chain, get a singleator (I use the Pyramid knockoff on my MTB, works great, $10 Ebay) or get an eccentric hub.

Ok im not sure if its a freewheel or cassete. Its six speed and is a shimano sis

You can make a search on the difference between freewheels and casettes. Freewheel is a one piece, casette consists of separatable cogs....

Freewheels are not "one piece", at least not in general. Mine never were on about four bikes. I used to change cogs around in them frequently.

Hmmm, I am not sure, but seems like you had a cassette. Did you? acording to this page http://sheldonbrown.com/free-k7.html

Most quality freewheels were to be designed for rebuilding/customizing, and were locked in place by a threaded small cog, like early cassettes.

If you have vertical dropouts, and want to use the derailer as a tensioner, then you must keep your front derailer too in order to hold the chain on. Check the single speed forum and do a search, there is tons of info. Don't miss Sheldon Brown's website either, he has some great info. Really it would be all you need.

You do? I have vert drops, and used a r. der. for a few days until my tensioner came in. As long as the chainline is good (it was), why the front?

(Not trying to be smart)

If you have a freewheel (most likely) you can replace it with a singlespeed BMX type freewheel for about $15. If you want to do it right, you'll need to then adjust your chainline by spacing the rear hub over to the right slightly so it lines up with the from chainring you select, then dish the rear rim back over to the left to center it.

If you want to go cheap, just select which front and rear gears you want to use, remove the rear derailler, and shorten the chain so it fits. Since you have a six-speed rear, you probably have horizontal dropouts and can get some chain adjustment. Otherwise, you'll need to keep the rear derailler (or get a chain tensioner) and adjust the limit screws to 'fix' the position of the cage for the selected cog. You can then remove the rear shifter and cable.

You may also be able to remove any unwanted chainrings and the front derailler.

I prefer the BMX freewhel myself with a shortened chain. It looks much cleaner without the extra cogs and derailler but takes a bit more work to get the wheel spaced correctly.

Thanks for all the advice. I don't have the tool to remove the freewhell/cassete yet. I will hopefully get that today.

You don't need to keep the front derailleur on. If you want to you can remove two of the chainrings; leave the middle on. If it's older, it doesn't have the ramps and pins to make shifting easier. That's good for SS. Find out what you have at the rear and follow the above advice. If it is a cassette, you're set but might have to scrounge up a few more spacers to fill the gap on the freehub. A shop should have some old stuff sitting around that will work. Line up your chain by positioning a single cog so that everything's on the same plane and you're good to go. An old derailleur, road if you can find one, works as a good chain tensioner. If your dropouts are semi-horizontal you may not need a tensioner. And if you haven't googled Sheldon Brown and gone to his site, do it. You'll learn all you need to know and more about your project.

Also, you may not need a chain tensioner even with vertical dropouts if you have your gear combo right. Sheldon Brown has a link to an Eric Harris site that allows you to find a gear that fits fine based on gear inches. Basically, since there are duplicate gears, once you find one you like, you can play around with the actual cogs to find a combo that fits a good chain length.
Also, BMX cogs should be about $6 for the back. Fronts are a little more expensive...