Fun project! Using the slightly different values of black pixels to map button clicks back onto the right object is a clever hack.
A bit of background: I'm a software engineer by trade, but I'm currently on sabbatical doing a year-long working holiday in Australia. I love riding bikes but only had the most beginner-level knowledge of them before I found a job at a bike shop. This was a fun personal project to try to capture some of what I've learned so far, targeted at fellow beginners. It's going to be incomplete/lacking if you already have some bike knowledge, but I hope you all enjoyed it all the same.
Please keep the feedback coming; it's late in Australia, but I want to make sure the bike info is at least accurate, if not comprehensive!