Bloody Lockring... I think

Ok, so now i can see (after op) Id like to get my fixed wheel bike up and running ASAP

When i took it to the LBS to have it checked over/brake assembled, they said it required a lockring to be fitted to stop the cog from slipping under braking (when skidding iirc).

I did not want to wait for the part as i wanted the bike back that day, so i took it home without this part.

Im a little unsure if this part is indeed missing from a few post when i posted the bike up in the projects section. I only have the components that are currently on the wheels/hubs and have not removed a lockring.

Can anyone confirm with confidence if i need to get hold of a lock ring for the cog? and if anything else is problematic on the bike.

Many thanks

You need a lockring.
hard to tell from that top pic but if thats a fixed hub it should have an extra bit of thread to screw on a lockring to secure the sprocket.

Anymore close pics of the hub?

Having had a lockring fail an hour ago and having ended in some scaffolding on the pavement, I can confirm that it is an essential piece of hardware. Your cog unsrews very easily otherwise, even if you don t skid.

Is the rear a track hub (i.e with two 'steps' of threading)?

Er, I can't see any thread for a lockring. You sure that's a trackhub?

Those are DA hi flange track hubs

aserota: take another picture of just the rear wheel, side on. It's impossible to tell from the pictures you currently have.

Did you fit the cog yourself, or were the wheels ready fitted? If you fitted the cog yourself, you would have had to remove the lockring first.

in fact, are you sure that's a fixed cog and not a freewheel? ie, when the bike is leaning against a wall, can you move the cranks backwards without the rear wheel turning? (sorry if this sounds patronising!)

Pictures in OP look like road hub to me.

only thing wrong with the bike is the rider......? Road use=lock ring (if it is indeed a fixie)

The hub has Shimano stamped on it, no?

Yeah, it's a Shimano hub, but road not track as far as I can tell.

Its a single sided DA track hub, fitted with a 15t EAI cog.

Dude, you need to go buy a lockring. Dura ace once are £5 from condor. If you don't have the tools to fit it, take the wheel in. You can't be riding round on the road without a lockring, fine on the track, good way to die on the road, plus you can wreck your hub.