Here's another, ultimate bike derailleur geekery -- Disraeli Gears: https://www.disraeligears.co.uk/site/home.html

I started checking out Dan's Motorcycle Repair Web page, expecting to read about Motorcycle Repair, and the first thing I do read about is the Bible. Good lord!

Me too! I'm a big fan of Rob Robinette's guitar amp page [1] for similar reasons

[1] https://robrobinette.com/Amp_Stuff.htm