>>1694385I was looking for this in this thread. There are several examples on Github, but here's an example of a Japanese guy making his own bike computer with a 5 USD Raspberry Pi and other components. I haven't looked into it, but the whole thing couldn't have costed him more than 50 USD.
https://github.com/hishizuka/pizero_bikecomputerMaybe /n/iggers aren't interested in DIY projects but I think this is really cool.