Probably the biggest downside to bikes is how they have to be ridden outside, powered by only your own dumb "feet" and "legs." You have to ride them around other people, along streets and sidewalks, sometimes in the rain and sometimes when it is uncomfortably hot. I mean, sure, they don't use any gas or fossil fuels and are usually pretty easily stored and offer exercise and environmental benefits and let you feel smugly superior to everyone you see/judge in a car, but otherwise they're pretty much the worst things ever, and that's before the chains slip off, which of course happens all the time, because bikes are terrible.