Hi! I have a back wheel mounted trainer (CyclOps Fluid) and I'd like to get something that will ideally help me track speed and cadence. Speed because then I can put it in my FitBit, and cadence because I think that's probably a good measurement to have too (I'm big on quantitative measurements).

The choices on Amazon are overwhelming and some seem unable to be used on a back wheel.

Any suggestions greatly appreciated!

Teresa