I have a rear wheel with a threaded single-speed freewheel.

I took my wheel off to clean the chain and cog on the freewheel.

When I put it all back together, I heard a weird noise whenever the chain moved across the freewheel. It's not audible when the freewheel is spinning, only when it's under load. The chain is well-lubed.

I'm wondering if some degreaser got into the bearings on the freewheel.

Here's the video of how it sounds.

http://www.youtube.com/watch?v=TkskR8fDEzE

Suggestions?