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Ha! Or really high gears. Those people grinding along at 15rpm with their kneecaps about to pop off into orbit. Just shift down.
I've seen one guy a few times on my commute who seems to be stuck in the easiest gear, he speeds away from lights and then puts in about 10 superfast pedal strokes, coasts for a bit and repeats all the way to the next set of lights. Never changes gear. I almost asked him about it once. Might offer to have a fiddle with his derailleur next time I spot him.
Always feel sorry for people who don't know what the gears do and happened to have bought their bike in a really low one. Must wonder what they're doing wrong