In a friction drive motor, a small, solid wheel rotates against the side of the tire in order to drive it. The first motorcycles used the same concept, with a motor mounted above the front wheel. The problem is that the drive rubs at the side of the tire. It's inefficient, and it quickly wears the sidewall away. Tires need to be replaced every couple hundred miles. For this reason, you'll seldom see electric bikes with this type of drive anymore.
The National Institute for Transportation and Communities believes ebikes remove barriers to cycling, such as physical limitations and challenging topography. The results of a recent survey “indicate that, by reducing the physical demands on the rider, e-bikes are encouraging more people to replace car trips with bike trips,” it says. The survey found that 37 percent of frequent cyclists and 27 percent of non- or seldom-cyclists who bought an ebike now primarily use their ebike to commute to work, an encouraging sign for transportation officials who want to increase bicycle commuting. (May 18 is National Bike to Work Day.)
Electric bikes are here in a big way. Liberated from some of the normal constraints of standard bike design like weight and gearing, e-bike design has exploded; if you can imagine it, someone has built it. From cargo bikes to city bikes, messenger bikes to mountain bikes, road bikes, and even beach cruisers, there is something for everyone. The beauty of e-bikes is they make the joy of cycling accessible to so many people in so many ways.