Single speeding an old road bike, help please...

Check out Sheldon Brown's site mentioned above, I converted an old frame with vertical dropouts and a cracked gear hanger using his tip for cutting down the axle length. Using that fix and a half link I sorted an fixed wheel with limited fuss that could take a range of ratio's.

I have to agree with Dave about the ENO hub, thats why i'm taking his s/s off his hands.

But if you don't have the cash to splash on something like that. Then something like this would do you fine without changing much apart from cassette and chainset

http://www.ebay.co.uk/itm/DMR-Single-Speed-Convertor-Tensioner-STS-Twin-...

best way to get good chain tension on vertical dropouts is with an ENO hub - not cheap though

Ratios, 48x15 will probably be good for flat commuting, 42 for rolling, you'll need to be very careful about chainline and tension.

Anything less, and you'll spin out on tiny descents, anything more, and if there's a headwind, you'll be overgeared.

You could just buy a track wheel off planet x, then the conversion would be easier.

Will be difficult to get the right chain tension on verts, may need a tensioner, or a different frame.

Hey Karlos. Shimano do a freewheel single speed cog. You can get on CRC for £22 I think. I use the 17t but I have a couple of hills on my commute. You'll need to pick up a single speed chain. I recommend the small chain ring (I'm assuming it's a 38 and also helps with the chainline) Also if you have skewers ditch the rear ones for nuts. And that will stop the rear wheel slipping. Either that or get a chain tensioner. Otherwise you will be retesioning the chain every few days. Hope that helps
Giff

This is pretty good stuff;

http://sheldonbrown.com/singlespeed.html

does it have sloping slot dropouts?