One of the most important systems for achieving this is the transmission, responsible for transferring energy from pedaling (and the motor) to the rear wheel. But what components exactly make it up? In this article, we explain them one by one and tell you what their function is.

1. Cranks and chainrings

The cranks are the parts that join the pedals to the bottom bracket axle. At the end of each crank is a chainring (or several, in some configurations), which is a toothed wheel that transmits movement to the chain.

On an electric bike, we usually use single-chainring configurations (a single chainring), since the motor compensates for the need for multiple developments. This simplifies maintenance and reduces weight.

2. Bottom bracket

The bottom bracket is the central axis on which the cranks rotate. On many e-bikes, this hub integrates torque and cadence sensors that help the system measure the rider's effort to intelligently adjust the motor's assistance.

3. Chain (or Belt)

The chain transmits the movement of the chainring to the rear cassette. On some urban electric bikes, it is replaced by a carbon belt, which is quieter and does not require lubrication, although it is not ideal for all types of use.

The chain must be resistant, since it supports the additional thrust of the motor in addition to human pedaling.

4. Cassette (or Sprockets)

The cassette is the set of sprockets located on the rear wheel. Depending on the selected gear, the chain moves between these sprockets to offer more or less resistance, which translates into greater speed or greater force. On e-bikes, wide-range cassettes are used to offer good versatility both on climbs and flat terrain.

5. Rear Derailleur (Front Derailleur)

The rear derailleur, or front derailleur, is the component that moves the chain from one sprocket to another. Many high-end electric bikes, like the ones we make at Bewatt, use electronic shifting to ensure precision and durability, even under load.

6. Shifters

These are located on the handlebars and allow the rider to select the desired gear. They can be mechanical or electronic, and their ergonomic design makes for quick and comfortable use, which is essential on technical or long-distance rides.

7. Chain tensioner (if applicable)

Some configurations (especially belt-drive or complex suspension systems) incorporate a chain tensioner to maintain proper tension and prevent the chain from slipping or hitting the frame.

Why is a good drivetrain important on an e-bike?

A well-adjusted, quality drivetrain improves pedaling efficiency, reduces motor wear, and provides a smoother, quieter riding experience. At Bewatt, we work with the best suppliers and carry out custom builds so that each bike is tailored to the style and needs of each customer.