I'm a beginner to bikes. I keep buying them, and the gears start "sticking"--they don't shift for longer and loger periods after I click the thingy. Eventually they become unuseable.

Sometimes I take it to a bike shop and try to explain my problem, only for the gears to magically work while I'm demonstrating for the dude.

Other times he does something and it works for about an hour, then it's back to being a piece of shit

what the fuck is going on and what do I do about it

pic. My bike in Laos. I like going on long bike tours of a country.