It’s always a smart idea to wear a helmet while cycling, and it’s especially important when you’re mountain biking. In fact, you should make sure to get a special helmet for off-road or extreme biking, as a typical bike helmet doesn’t necessarily provide enough protection for falling off your biking uphill, off-road, at motor-powered speeds. Always look for a helmet with MIPS (Multi-directional Impact Protection), and preferably with some form of face/eye protection like a visor or even a full face guard. Smith, POC, Trek, and Fox all make some outstanding electric mountain bike helmets.