Standing on your pedals and huffing and puffing up a hill is totally unnecessary in the lithium-ion era. E-bikes—basically standard two-wheelers with motors and batteries squirreled away in their frames—put a little wind at your back. Torque sensors near the pedals signal the motors to kick in when you're pedaling, helping you boost your cruising speed to 28 miles per hour. If the juice in the battery dries up, you can ride on using leg power, just like a regular bike. While e-bikes are a blast to ride, not every model is built for every terrain. Pedal-assisted mountain bikes are major overkill for commuting, and a casual beach cruiser isn't very useful on a rocky, rooty trail through the woods. This selection of souped-up whips can tackle any terrain—from urban jungle to actual jungle.