The greatest advantage of conventional bicycle computers is that they can measure instantaneous velocity precisely thanks to wheel sensors. However, measured data is often visualised in a less user-friendly way because of the limited display size of conventional bike computer gadgets. This fact leads to the idea to use smartphones as modern bicycle computers. However, currently used smartphone-based bike computer applications require complex hardware devices to measure instantaneous velocity precisely. Without these special devices, bike computer applications can only rely on GPS data to estimate current speed of bicycle.
In my solution, a wheel sensor is applied to determine instantaneous velocity precisely. However, instead of complex hardware devices, only a 4-pole Jack connector is used to attach the wheel sensor to the smartphone. This solution combines the advantages of precise velocity measurement of conventional bike computers with the ability of smartphones to display measured data in a user-friendly way.
After implementing the application, I compared my solution to other velocity measurement methods available on smartphones. Then I took measurements to prove that my solution is precise and accurate in velocity and distance determination. Description of hardware and software components of my solution and measurement results can be found in this essay.