A Kalkhoff Pedelec is a lot more than simply bolting a motor onto a great bike. Their electric-assist bicycles utilize a brushless DC motor system that is lightweight, precisely-controlled, efficient, low-maintenance, and reliable. The Panasonic drive system is center drive, meaning that it's designed to be in the middle of the bike for a low center of gravity, stability and an easy integration with the drivetrain. The drive unit is more than just a motor; it also has a torque sensor and controller unit as well - all in the weatherproof casing, surrounding the motor. The torque sensor and the controller senses how hard you're pedaling and adjusts how much assistance the motor gives you through the drive sprocket.
Yes, you read that right – north of £4k for a bike. But then, this is basically the top end of the mountain e-bike market, and you do get a lot of bike for your buck: a Yamaha Lithium battery, masterful Magura brakes, mud-slaying tyres, and – my favourite flourish of all – a hydraulic seat post that you can adjust on the move (surprisingly useful when navigating tricky downhill trails, as it means you can depress the saddle out of the way with the press of a button).
China's experience, as the leading e-bike world market, has raised concerns about road traffic safety and several cities have considered banning them from bicycle lanes. As the number of e-bikes increased and more powerful motors are used, capable of reaching up to 30 miles per hour (48 km/h), the number of traffic accidents have risen significantly in China. E-bike riders are more likely than a car driver to be killed or injured in a collision, and because e-bikers use conventional bicycle lanes they mix with slower-moving bicycles and pedestrians, increasing the risk of traffic collisions.
For many bikes, battery range is more important that total power (because they're all pretty powerful). You want a bike that delivers a range long enough for your rides at the power levels you want. Most e-bikes will have three to five levels of assist kicking in anywhere from 25 percent of you pedal power to 200 percent boost. Consider how fast the battery takes to recharge, especially if you'll be using your bike for long commutes.