Review: Polarna M4 Foldable Electric Bike (20″ Fat Tire, 750W, 35mph, 8-Speed)
Read: 15 mins.Polarna M4 is a hefty, foldable electric bike with 20" fat tires, 8 gears, and a 750W motor capable of going at least 30mph. It was the fastest bicycle we had tested yet, was both exhilarating and scary, and could still accommodate a 5'1" rider.