5 Tech Revolutions That Created The Modern ebike

Modern pedal-assist bikes are amazing. This is how it happened.

Gazelle T10 Speed hidden eBike battery, built into the downtube.
Gazelle T10 Speed hidden eBike battery, built into the downtube.Bosch

What Makes A Modern Ebike So Good?

The modern eBike or pedal-electric bicycle exists because of five technological breakthroughs that made seamless pedal assist possible. Ebikes have been around a long time (read about eBike history here), but it wasn't until the 1990s that their modern form began to take shape. It was in the mid-2000s when assist technology combined with falling lithium-ion battery costs to help usher in a new era of transportation.

Here are the five tech breakthroughs that made affordable, lightweight eBikes possible:

1. A high-energy-density and affordable rechargeable battery to supply the power. This is the lithium-ion chemistry commercialized by Sony in 1992 and now powering electric cars, mobile phones, and pretty much every other modern device. Typical electric-bike batteries weigh only 6–7 pounds and can provide 1,000 cycles of charge/discharge. Batteries are protected by electronic systems that prevent excessive temperatures from being reached (battery charging and discharge generate heat) and prevent damage from excessive battery discharge.

Bosch Active Line Plus motor on white background.
Hidden inside the Bosch Active Line Plus motor housing is a complex array of gears, circuitry and a permanent magnet motor. Despite its complex nature, it still has Q factor, or width between cranks just 10mm greater than a standard bicycle.Bosch

2. Light, powerful, and long-lasting electric motors. These are brushless permanent-magnet DC motors, their small size made possible by the same very powerful neodymium rare-earth magnets (10 times more powerful than Alnico) that have made recent automotive starters so tiny.

3. Accurate, affordable non-contact torque sensors that measure the torque you apply to the pedal shaft. The shaft is magnetized in a particular direction and the torque applied by your pedaling, by ever-so-slightly twisting the shaft, alters that magnetization in a measurable way. This effect is called magnetoelasticity.

4. Power electronics based on fast-switching high-current Insulated-Gate Bipolar Transistors (IGBTs). Sensors continuously monitor the angular position of the motor's rotor. The computer-phased IGBT switching of battery current to the motor's many stator windings generates a rotating magnetic field that stays just ahead of the whirling permanent magnets of the rotor, thereby strongly pulling them around at motor speeds from zero to 4,500 rpm or higher. Motor torque is multiplied and its speed reduced by two or more stages of gear reduction to assist you in driving the front sprocket.

5. Digital connectivity that can allow you to communicate with your bicycle's motor system from a smartphone or other handheld device. Although this is not necessarily key to the basic functioning of an eBike, the interface allows for great control of performance and insight into remaining range versus speed, percentage of boost, and more, that reduce range anxiety and increase our enjoyment of eBikes.