Scientists have proven it: Florida is flatter than a pancake. In fact, it's flatter than Kansas, Nebraska, or any other state in the whole country. We live in a drained swamp that's slowly refilling from sea-level rise. That means if you're the type of cyclist who gets off on huffing up a hill and then flying down the backslope, you're pretty much out of luck here. There is one notable exception: the William Powell Bridge that spans between Hobie Island Beach Park and Virginia Key on the way to Key Biscayne. Built in 1985 to be tall enough so boats can pass beneath it, the bridge has a fringe benefit of its steep grade: Cyclists can finally click through all their gears. Sure, the way up is a legit workout, but you can find inspiration in the glorious views of Brickell and downtown and the sparkling blue grandeur of Biscayne Bay. Then the way down is all adrenaline, where you can let your bike fly and try to keep up with the cars. But be warned: This is a bridge, after all, so there's no such thing as a one-way ride. If you want to get home, you'll have to scale this beast again.