Fitness is always in, and people who exercise always need feedback on how many calories they have burnt, or how many kilometers one has cycled or how fast they were going etc. Bicycle manufacturers have tuned in to these requirements and have made sure that the cycles sold provide a lot of information. This is where Magnetic Proximity Sensors are useful. Reed Switch based Proximity sensors are used to display the speed of the wheel which is then translated by the on-board microprocessor to other information such as calories burnt, top speed, average speed and even pushed to hand held devices. The wheel speed is sensed by securing two magnets to opposite ends of the wheel and with the sensor mounted near the brake pads, to generate a square wave output that is fed to the microprocessor. This in turn is used to trigger other information, for example to start a timer to keep track of start and end times, which is then used with owner information such as height, weight age and sex, to calculate calories burnt.