I was sitting in the park the other day and I heard some kids riding outdoor exercise bikes. They were clearly a bit rusty, because the big metal resistance wheels made a nasty squeaking noise. But then I got to thinking, well, what if you made a noise deliberately? You could design the big metal wheel to resonate at a particular pitch, and with a few of them in a row tuned to different frequencies you might even get some nice music out.
It seemed like a cool idea, but one that wouldn't be very easy for me to try without investing in some welding equipment. I figured I'd just leave it in the unrequited pile, but then I realised that I could just make a simple version of it using much more readily available tools. So I put together the above demo; go ahead, you can click and hold the bikes to rev them up and listen to the harmonious sound of singing bicycles.
It worked in all the browsers I tested it in, though the Safari version is a bit glitchy. You can find the source code on Github and a standalone version on my demoserver. The parameters are customisable, so you can make your own version with different colours and tones if that's something you'd like to do.
It really is a good feeling to just go all in on a silly spur of the moment idea like this. I doubt that my singing bikes will ever actually get built, but I'm glad that, in my own way, I could make them real.