Fixed-gear bicycles are still popular nowadays because they are simple, low maintenance, make for great winter bikes and urban commuters as well, as long as you don’t have to cope with steep hills.

Arash Guity can't stop pedaling. That's because the "fixie" bicycle he rides to work has no freewheel, which means there is no such thing as coasting. But Guity, a 34-year-old energy consultant, doesn ...