I put a new chain on my singlespeed last week (after not riding it at all over the summer). Now its making a right racket when I'm stood up and pedaling (kind of a clanking sound)

my feeling is its either

a – I need a new bottom bracket
b- I need a new chairing and/ or sprocket (I have had them on there since the bike was built and this is my third or fourth chain – I check for chain stretch on my geared bikes but never on my SS)

any ideas on whats most likely so I know what to try first?

have you got a bashring it might be rubbing against?

1st thing I would do is put the old chain back on to see if the noise goes away.

see if the noise occurs in time with your pedal stroke, or the rear wheel, or the chain. helps to narrow down the source

no bashring

I can't try the old chain as that got thrown away when I partially stripped the bike at the end of last winter

the noise occurs for around half a pedal stroke if that makes any sense – so I get a clank every revolution, followed by a short silence, then another clank as I continue to spin

freewheel?
try skipping the chain on one tooth.

BB at a guess. Does it only work when you stand and honk or during seated pedalling? Try pedalling one footed with each leg and see if the same with both or if just follows one leg. May then be pedal. Do you feel anything or just a noise?

A couple more things:

* Remove the chainring, clean and grease the chainring bolts and flats. Also check to see how worn the chainring is – if it's sharktoothed, and you've not flipped it before, flip it.

* check the freewheel teeth too – if they are worn, then the teeth may be chainsucking the chain as you pedal hard – but it won't show if you're spinning.

Basically, if you've got a very worn drivetrain, and you've swapped to a brand new chain, it will make noise when you crank hard. It's really important, for this reason, to hang on to old chains. If you have a sprocket rather than a freewheel, it wouldn't hurt to try swapping to a new sprocket to see if the noise goes away. Also try comparing new chainrings (or other chainrings) to see how worn the ones on your singlespeed are.

HTH

good advice people

hadn't thought of flipping the chainring – could also try flipping the sprocket I think (thought I would need to buy new ones)

don't think its the pedals – they spent a couple of months on my roadbike over the summer (got proper road pedals now) and they were fine then

Is the sprocket one for a cassette hub? In that case, definitely flip it and the chainring. I've got a White Industries freewheel and a Thorn chainring, and the chainring is definitely hooked, while the freewheel seems pretty happy – mind you, it is stainless steel. Flipping the chainring and fitting a brand new chain has quietened things down on mine no end.

Also, try grabbing the frame with one hand and a crank with the other. Try to see if the cranks move in the BB shell by wobbling them around. You can and should use as much force as you can manage, after all it still won't be as much as your legs can exert. If there is significant play, get a new BB anyway.