Looking for a wee help up in relation to sourcing a single speed cog that will fit onto the same size of thread that the current Shimano single speed free wheel cogs fit onto. Any suggestions?

Ahhh – what are you after? Something to fit a shimano splined freehub body or a threaded hub?

I’ve basically got an old genesis IO hub which is now laced with 700cc rims on my commute bike. I fancy giving this fixed gear thingy a wee try!

Sorry, meant to say its a threaded hub.

Something like this: http://www.charliethebikemonger.com/gusset-track-cog-177-p.asp
Or a Surly cog: http://www.charliethebikemonger.com/surly-fixed-cogs-156-p.asp
Or On-One have some: http://www.on-one.co.uk/c/q/drivetrain/track_sprockets

“That’ll do pig”

Cheers mucho!

Its unlikely to fit if a freewheel went on,

You could run a cog by itself but I wouldn’t do it without a lockring.

Just get a proper fixed hub.

Or get a velosolo 6 bolt cog to mount onto you disc mount.

You need a reverse threaded lockring to use a track cog, not advisable to use it on a normal freewheel threaded hub as you’ll just spin it straight off as soon as you back-pedal. If it has a disc mount best bet would be to try a bolt on disc cog if you want to try fixed.

like this:

velosolo

Its debatable as to whether you need a lockring. Just tighten the cog with a large chainwhip, then ride up a few steep hills, that will get it rather tight.
Its unlikely to unscrew unless you are regularly doing skid stops. Best to avoid skid stops, just use a front and rear brake instead.

you can do it with a track cog,and an old bb lock ring,as the threads are the same.
but it WILL end in tears.buy a track hub,and as Sam said,use a lock ring.