October 20, 2022 - The big news behind Trek’s new Fuel EXe eMTB is its compact and lightweight HPR50 drive system with patented harmonic pin-ring technology pioneered by the TQ-Group, a multi award-winning German robotics manufacturer.

TQ’s novel harmonic pin-ring concept, first introduced back in 2012, does away with cogs, belts and planetary gears in favour of a more refined system that includes an elliptical wave generator and two gears — internal and external — that sit on a central axis and are connected by a flexible pin-ring transmitter.

The unique e-drive system can achieve the required reduction between the RPM of the rider and the motor in just one step, with a reduction ratio that is about 1/3 of other systems, which need several steps. 

With 50Nm of torque, the HPR50 motor boasts a torque density of 82Nm/dm³, touted as the highest e-bike torque density on the market. 

Claimed as the smallest, lightest and quietest e-drive system in its class, the HPR50 tips the scales at just 1,800g, and it pairs with a 360Wh high-density battery that uses 50% less space for a 3.9kg package. 

Integrated into the frame, the TQ display provides battery status, riding mode and available range. With ANT+, you can connect your smartphone or bike computer.

The Remote allows you to switch between the three power-assist modes without taking your hands off the handlebars, and a walk mode is also available. For longer rides a lightweight 160Wh Range Extender fits into any standard bottle cage.

The HPR50 tucks neatly behind the front chainring, similar to a regular bike. Its small size allows for a traditional 135mm Q-factor delivering the same comfortable riding position as a non-electric bike, according to Trek.

Thanks to the HPR50’s integrated freewheel, the Fuel EXe can be pedalled like a bike as no internal components run when the drive is switched off.

With roots in the aerospace and robotics sectors, TQ’s harmonic pin-ring precision systems have been used in the aviation, medical and space industries.

The release of TQ’s powerful HPR 120S, which delivers 120Nm of torque, means we can expect to see more from this innovative company in the world of e-bikes.