Advice: Wheels for the uneducated

im new to singlespeed and at the moment ive just got a bmx free wheel on my road bike. is it possible to get other cogs or fixed cogs which will fit on my wheel or do i need a new type of wheel?

I dont really know about bmx but depends on the hub
a pic would help.

I depends on the threads of the hub.

If it's a proper road wheel, then no, you cannot make it fixed without doing something silly.
Proper track hubs have two sets of threads, one you screw on like normal, the other is counter threaded so that it holds your cog on better.

Mr. Lightyear is correct, pictures would help.

ignore the slack chain thats been sorted

http://www.flickr.com/photos/40612430@N08/3731438091/

its a 27 inch wheel with threads on one side. can i not put a cog on then tighten it with a lock ring so its then fixed?

could you make your photos any smaller please??

you cant stick a lockring on a free wheel to 'make it fixed'
If you've only got threads on one side, its either a track only hub, which is what you want, or its a road hub, which is no good.

for a fixed hub, needs to look like this:
2 threads next to each other. the inner thread allows you to screw on the cog in one direction (clockwise i think) then the outer thread is for the lockring (anticlock)

can you recommend any needs to be cheap

You cannot make the hub in your photo fixed.

You would need a proper track hub to do this.

The catch is, that it won't be spaced properly and you would need to have someone who knows what they are doing space it out.

http://www.londonfgss.com/thread11148.html
see hubs

I depends on the threads of the hub.

If it's a proper road wheel, then no, you cannot make it fixed without doing something silly.
.

Most vintage road hubs are flip-flop with a fixed side from what ive noticed.