First off, flip the wheel and run the fixed cog, even if you're not planning to stay that way, it'll soon tell you if it's the freewheel making the noise or not.

Spokes can produce a sort of creaking noise, so check to see if they are all evenly tensioned. Just grab 'parallel' pairs of spokes and squeeze them, you'll soon tell if they aren't evenly tensioned. The other method is to tap each spoke with a screwdriver and listen to the 'ping' - they should all sound the same.

Creaks can also come from cranks or bottom brackets that aren't tightened properly and I'm guessing the chainring can also make noise if a bolt is loose.

Finally, if you're running a Brooks, there's a creak that occurs between the nose and the leather - a shot of chain oil fixes that.

But first off, just flip the wheel and go for a ride up the street. If the noise is gone, it's the freewheel, if it's not, you're in for an interesting few weeks while you trace it.

Richard