If you ride a bike even remotely seriously, your bike is not cheap… It might not be expensive, but you quickly realize why cheap bikes are cheap.

Spot on. I've got about $3k into my bike, but it's not a fancy race bike (it's a steel fixed gear), so I invested in bombproof parts that could end up outliving me. Once a year I'll replace the tires/chain/brake pads, service the bearings, and strip/regrease a few parts, so the running cost is maybe $15/month. If you've got a road bike with a 2x drivetrain, or if you're paying people to service your bike that might go up to $30/month, but still negligible compared to a car.