Monitor your pedalling cadence andor speed as you ride with these easy to install wireless sensors simply attach the sensors and ride with no magnets or other exposed parts to line up these sensors are easy to install maintain and move between bikes the cadence sensor fastens to any crank arm size and measures pedal strokes per minute so you can get the most out of your training the speed sensor attaches to the hub of either wheel and self calibrates with your edge to give you accurat