Everything I read about spinning bikes was that your rode for time, more than distance or speed ( I know, two different measurements, tell that to Han Solo who did the Kessel run in under 12 parsecs). Nevertheless, I wouldn't mind knowing what is the what, so I retrofitted a cheap bicycle computer to the wheel and frame of a Sunny Health spinning bike. The piece (just a magnet) that goes on the spoke is attached with velcro, and some zip ties were long enough to attach the detector to the frame by the wheel. The wheel is only 18 inch diameter, giving a circumference of 1436 mm. Entered that in the computer and seems pretty accurate.