Cog slippage.
 

I strip my first hub, get a new wheel rotafix the cog on like there is no tomorrow, tighten the lock ring to a limit that would scare most.

Today on a descent, I felt slippage. I pedal forward real quick it slips back. What am I doing wrong. I don't think there is any damage, but thats why I specifically got a fixed/fixed wheel.

What else can I do?

how many miles has the chain had?

how old are your tyres?

how old is the bb?

vertical or horizontal dropouts?

hows your tension?

Did you put a **** ton of grease onto all the threads on the cog and lockring before putting them on? If not, you should.

Umm..I think you mean a ton of locktite, not grease.

Everything is greased up, I am running a new chain, new BB, horizontal drop outs, crappy old tires, and the tension is good.

No, he means a ton of grease. There's no reason to use locktite on your cog or lockring unless you are running a suicide setup.

chainring bolts not not tightened enough?
je ne sais pas

For the past few days I have avoided using any negative force on the cog (never back pedaling or resisting). At every stop that exceeds 2min I tighten my lock ring a bit, it doesn't really get much tighter, not even 2 deg turns can be made.

Since you don't say what the brand names are, better quality components?

That may be your problem. Overtightening can strip the hub. Even if that's not what happened, overtightening the cog could lead to a slight gap between the cog and the lockring (doubtful, but I can see that happening).

Dimension fixed hub, surly 15t cog, and some normal lock ring.

I hope its not that. I'm just going to ride it out is if it gets worse.

new chain? it could still be stretching itself.
LBS?

+ 1

you can really strip a generic taiwanese hub simply overtightening the cog on it, I've done it on an OnOne hub with OnOne cog (taiwanese stuff rebraded by OnOne)

Are you joking or are you just a moron? None of this has anything to do with a cog slipping.

To the OP, you should grease the living hell out of the threads, run the cog on as tight as you can, pound up a nice long hill with a lockring wrench in your back pocket, then get off of your bike without any resistance and tighten that lockring up really good.

the quality of drivetrain parts is paramount in my opinion. there is no reason whatsoever to save $5-$10 on cogs and lockrings. just buy the NJS stuff (not going on an NJS tyraid), it is'nt that expensive and you will know it is quality. the problem with the cheaper components is the metalurgy and machining. the shimano, EAI stuff that is stamped is going to last longer and be more reliable. the tolerances of production and quality metal alloys make a world of difference.

Your problem is all 3 of your parts are of not-so awesome quality.

Dimension hub: X
Surly cog: X
Normal lockring <- Don't know what this means, either it's generic which is **** or it's good say phil or dura ace.

He's thinking that the OP isn't really feeling the cog/lockring combo moving but something else although I can't imagine it'd be anything he suggested either. If someone feels slipping in the drivetrain, it's 99.99% certainty the cog/lockring.

The other time it will be completely obvious that the drivetrain is shot.

Make sure it's not the BB that's loose.

thanks for that, thats exactly what i was saying.