Annoying drag when freewheeling

PJPenrouz

I put together this bike (see pict1), for city riding, some trails and mostly for fun. It's a dual singlespeed with sliding dropouts (see pict2) - I change gear by hand from 36x13 to 32x17.. When I turn the cranks counterclockwise, for each turn there is this rubbing (the movement ceases to be smooth for a while) - I first thought the BB shell needs facing because it occurs once in each crank turn, but the rubbing actually makes the rear wheel turn. Is it the rear hub? I've tried different chain - to no avail. I've tried to fiddle with the SS spacer set and the chainline - no difference. It increases with the chain tension - if the chain is looser, it's barely detectable. The cranks (Hone HTII) and the cogs are new. Any ideas?
Cheers
http://www.photobox.co.uk/album/album_p ... 1601698819
http://www.photobox.co.uk/album/album_p ... 1601698813

nicklouse

chain ring not centered.

run less tension on the chain.

Big Red S

The chain's too tight, and putting loading on the freehub that's not supposed to be there unless the ratchet's engaged.

The chain should sag ever-so-slightly between the cogs, it shouldn't be as tight as you can get it.

PJPenrouz

Thanks.
Nick, by "chain ring not centered." do you mean the chainline is not correct or the BB shell needs facing (or something completely else)?

nicklouse

Sometimes if you change the position of the chain ring (undo ring bolts and move around one hole at a time) you can get the tension to change less.

but as BRS said the chain should not be that tight of the freebody will not be lasting too long.