Gearing: none (many hub motors, one motor revolution = one wheel revolution), fixed gear reduction for more torque, varies when geared motor drives the chain through the bicycle gears which increases torque about 50% (in low gear) for better hill-climbing and offers better top-end speed (in high gear) than direct drive systems using motors of similar wattage.
If you’re interested in an ebike, you have a couple of options: converting your existing bike or buying an electric version. Abadie says a bike suitable for conversion will have a powerful brake system, wider tires and a strong frame that can hold the motor and battery. He charges $800 to $1,200 to find the right parts and motors for a particular bike.
James LaLonde, senior brand manager for Cannondale, agrees. He says their entry-level (read: good for beginners and more affordable) e-bike—the Quick Neo—has a battery life that lasts up to 70 miles. “If you ride for a full day, you may want to recharge it before you go to bed. But if you’re just commuting [a few miles], you could use it for a full week before you need to plug in. Then it’s a four-hour recharge when it’s completely dead.” (Of course, you don’t have to wait for it to get to zero if you want a shorter charge time.)

E-bikes mostly use motors and battery options from a few major suppliers: Bosch, Yamaha, Shimano, and Brose. A few other brands exist, but are less reliable or powerful. Some, like the Yamaha system, have more torque and others are quieter. But generally all four make good options. Look for motor output (in watts) which will give you an idea of total power. But watt hours (Wh) is perhaps a better figure to use—it takes into account battery output and life to give a truer reflection of power.