or have I put my hub back together incorrectly?

I have just rebuilt my rear hub with a new freehub and cassette etc the wheel spins freely and the freehub seems to be working ok.

However, on my test up and down the street I attempted to back-pedal – the chain just went slack rather than rotating smoothly in reverse.

Is this because the freehub needs running in or have I tightened something up too much?

Have you done any other work at the same time? Could be that one, or both, of your jockey wheels isn't spinning freely

Its a brand new rear mech and chain too.

hmm, I've never had that problem with new free-hubs or hubs, though I did have a Shimano BMX freewheel that was a bit sticky. If you lift the back end and pedal it normally with your hands then let go of the crank does it freewheel or does it try and turn the crank as it goes?

May just be sticky or overpacked grease from the factory which will loosen up with use.

Sounds like you've re-assembled it incorrectly. Strip it down again and have another go. Go to the Park website for info.

Could also possibly be worn front rings not 'letting go' of the chain when you backpedal, causing chainsuck when you pedal backwards.

Its a brand new chain set too.

Mike – I've just tried what you said – lifted the back wheel up, and turned the pedals. The wheel spun normally and the cranks stayed still.

I've got the bike upside down in the kitchen now!

The answer was, Yes, they do… 24 miles today and its now spinning freely and well and truely christened.

Did you grease it? Sometimes if the grease is too thick it will cause a surprising amount of friction. If so, remove it and wipe it off.

I hadn't put any grease on the freehub, just on the bearings in the cup and cone bit.

Sorry fr the hijack – but if you free wheel and the cranks move what does that mean? I'm getting that on a 2nd hand single speed bike – does that mean the freehubs knackered?

Well, I had to change mine as it was failing to engage drive, whereas yours sounds like it is seized in the 'on' position (if that makes sense)

Someone more knowledgeable than me will be along shortly.