Monitor your pedaling cadence andor speed as you ride with these easy to install wireless sensorssimply 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 bikesthe cadence sensor fastens to any crank arm size and measures pedal strokes per minute so you can get the most out of your trainingthe speed sensor attaches to the hub of either wheel and self calibrates with your edge to give you accurate speed