How do I even explain this. Ok my drive drain runs smoothly in 95% of the cases. Dura Ace in the front Surly playing in the back with a 17T. All driven by a Sram track chain. It sometimes now happens, mostly when riding uphill that there is a certain miss in the game, you can even hear it when you listen closely. You do feel it in the pedals, its like something is loose for a split second or something is not fully engaging. Its really heard to explain but maybe you have/had this as well and know what I’m talking about. Any ideas appreciated. I ride brake less and don’t want my drive train to suddenly fail on me.
How’s the chain line/wear - master link catching?
the chain line is pretty perfect I’d say but the chain ist still the first one when I built up this bike 3 years ago. I don’t ride it that much anymore so its hard to say how many k’s the chain has on it.
My guesses:
- dodgy sram joiner link
- bent/damaged tooth on chainring or cog
- two chain links seized together
- new bike required
Cog slipping loose/tight?
What he said, or she. I don’t wish to apply gender stereotypes to Tomatoes.
Check chainring bolts?
Is your chain tensioned super tight? Could it be binding when you put the extra load on it going uphill? Will we ever stop answering your question with more questions?
Are you using Biopace?
It is pretty tight yes…mmmh…everything else looks/seems to be fine. How do I check if a track chain is worn out without having a chain checker tool?
Cog slipping is my guess as well. It might be tightening up when going uphill. It’s a weird feeling when it happens,
Lets assume its a slipping cog, would this mean I need a new cog or could the flanges at the hub be worn out as well? Meaning I would need a new hub/wheel etc…
Oh man… I’m on the edge of my seat every time I get to this thread thinking there will be a resolution. But so far no dice. 
On the latest suggestion. Chuck a lockring spanner in your pocket. Wait until the cog ‘slips’ going up a hill. Then get off and see if you can tighten the lockring at all. Might stop it loosening again.
It depends on how long it’s been like this, and how good your hubs are. Normally if it slips a little you can just stomp up a big hill to make sure it tight, and the tighten up the locking at the top, and it should be ok, but if the hubs are low quality aluminium the thread will be destroyed by now, but you would have noticed it getting worse… The age and wear on the cog is irrelevant to this, it’s all about lockrings and hubs
Another thing - some cogs can be a fraction thinner than the hub is designed for, meaning that when you tighten the lockring, it bottoms out before it hits the cog. This leaves a tiny gap between the lockring and cog, resulting in slipping each way when you pedal/skid.
I’ve seen this happen with modern hubs that are designed for thicker cogs (e.g. Surly) rather than skinnier ones (vintage Dura Ace)