For all you guys looking for a degree wheel. For the last few month I have been using this angle tool pictured below. The cool thing is that the needle is attached like a compass needle with a weight on the bottom, so it always point vertically up.
I cut the flat parts of, so I only have the round gauge

On the back I glued a 5mm ring (see pic) in the center with which I mount it on the crank.
This piece is much easier to use and IMHO also more precise than a degree wheel.