For serious cyclists
If you've always dreamed of maneuvering a fixie through the Diagonal traffic, this is the place to find one. Deviant offers the rental bikes you won't see anywhere else in town: fixed-wheel, single-speed, BMX and dirt jump bikes—and skateboards too. The Deviants custom-build their own, quite elegant bikes; they would be glad to make one for you if you're staying for a while.
Bikes start at €25 per day, all-inclusive; you can book online.