trying to run a 34t ss specific ring, 17t superstar sprocket, superstar tensioner and a sram ss chain.

under load (on the stand its fine) it seems to pick up somewhere and clunk, it happens probably twice in a full pedal revolution.

i can’t see where its catching (or whatever is heppening), i’ve messed with the chain alignment, tensioner alignment and, well, what else is there!?

please help, it’s breaking me!

Check you don’t have any stiff chain links, they would sit high on the ring and sprocket.

I just set up my bike with exactly the same kit lol, hows the chain? any stiff links? Is there a noticeably tight/loose point in the chain?

spanking new everything, chain is as supple as a supple thing coated in olive oil… well, wiped down with gt85 but you get the picture

Check for stiff links
check the chainline is spot on
check the chainring is centered!

if you turn the cranks, does the chainring alternate between tight and loose?
if so, its probably clunking at one of the extremes?

to sort it, half loosen the chainring bolts, ie: so that they hold the ring in place, but are not tight.
then rotate the cranksto the point where the chain is tightest, and tap the chain itself to shift the chainring.
re spin the cranks, repeat till the chain is evenly tensioned through the rotation, and then carefully, gently, so as not to shift the chainring, nip it back up again.

oo, if you using a tensioner, it could be that. (and negate my previous point)

is the jockey centered when under load. this is a different position to when turning the pedals backwards on my old SS, (which is due to the mech hanger being not quite straight)

hmmmm… will check the hanger.

dont think its the hanger, its pretty straight to the eye.

Just a guess, could it be that you’re using a 1/8″ SS chain and the tensioner is meant for 3/32″ ?

How tight is the chain? Is the tensioner pulling it down? I’m thinking perhaps the chain is too long and the clunk under load is the chain climbing over the teth on the sprocket. You may need a half link in order to shorten the chain. A really good sprocket like the groove armada (on-one sell them) with nice high teeth may also solve it…or you may need to do both.

I had problems with not enough chain wrap on the sprocket trying to tension down, shortened chain and tensioned up, no clunk

What’s your freewheel like, could be pawl troubles.

You need more chain on your cog. Tension up, or down but with less links.

Oh and GT85 is not good chain oil

How’s the chain joined? Powerlinks and similar on ss chains can catch on a tensioner.

Is the clunk once per crank rev, once per rear wheel or roughly iirc once every threeIsh crank revs?

That’ll indicate if the problem is at the chainring, rear wheel or sprocket/tensioner respectively.