Heybike has introduced its latest X-series fat-tire e-bikes in the US. The Heybike X-series consists of two e-bikes: the Mars 3.0 and the Ranger 3.0 Pro. Both fat-tire e-bikes come with a foldable design, a top speed of 28 mph (45 kph), an aluminum alloy frame, a full suspension system, 4-inch fat tires, and an IP65 water resistance rating.