Small. Light. Quiet. Natural.

The heart of TQ-Group’s e-bike transmission is the HPR50 – short for harmonic pin ring transmission with 50 Nm of torque. What’s a harmonic pin ring transmission? It’s a relatively simple, yet ingenious, drive mechanism that operates similarly to a rotary motor, but more refined. Internally, there are three concentric precision pieces, an elliptical wave generator, an inner flex spline and a circular spline, that come together to propel you forward, while remaining small and lightweight. Compared to classic toothed gears and belt drives, a harmonic pin ring transmission is more compact, more powerful, feels smoother and is more durable.

Due to their precision, durability and compact design, harmonic pin ring transmissions and specifically TQ harmonic pin ring drives, have been used in the space industry, aviation, the medical industry and robotics. For all the same reasons they succeed in moon landers and surgery robots, they work brilliantly in e-bikes as well.


Tipping the scale at just 1,800 g, the HPR50 is 1,100-grams lighter than other high-powered drive systems.


HPR50 tucks neatly behind the front chainring for the clean look of a traditional bike.


Foregoing noisy belts and geared teeth, the HPR50 comes in as much quieter than other systems.

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The small size of HPR50 allows for a minimal 135 mm Q-factor (the distance between the outside of one crank and the outside of the opposite crank), providing a comfortable riding position similar to a non-electric bike.

Power density

A balanced 50 Nm of torque gives just the right amount of assist that isn’t overwhelming, and doesn’t jerk you around like a full-powered 85-90 Nm e-bike.

A better battery


360 Wh packed into a lightweight 1,835 g package.


Fully charge in 2-3 hours.


Daisy-chain to charge your booster and battery simultaneously.


Simple removal, just unplug, remove the downtube guard and two bolts, and pull out by the handle.


An LED charge display illuminates to indicate how much charge your battery has, and lets you know when it's full.

Fitting snugly into the existing bottle cage, the Range Extender offers an additional 160 Wh of power to increase the range of your ride by 44%

Mounted flush into the top tube, a 5-cm display keeps your set-up discrete from a side-view, while providing crisp and bright details from the bird’s eye. The bright contrast stays visible in blinding sunlight and offers just enough information to be useful without overwhelming you at a glance. A single button turns the system on and off, and toggles through riding screens.

Control at your fingertips

Fuel EXe handlebar-located remote

Small, stealthy and easy for everyone but your thumb to miss. The handlebar-located remote, developed specifically for mountain bikes, features two buttons that allow you to toggle through support modes, engage walk assist and turn off assistance right from the comfort of your grips. Easily unplug the remote when you need to change or replace components.

Domane+ SLR top-mounted buttons

Discreet yet intuitive, the Domane+ SLR has mode control buttons that are located on the top, so you can easily and intuitively switch between the three electric levels of natural-feeling assist. It’s just like shifting a regular road bike, with a little extra pep in your pedals.

A bike this advanced and refined deserves an app equally advanced and refined.

Tuned to you

You’re in control with three completely adjustable motor tune settings that can be easily tweaked on the fly.

How far can you go?

See your estimated ride range to plan your route without the worry that you might run out of juice.

Plan your ride

Map out the perfect ride with easy-to-use routes for road and trail alike.

See your stats

Log your rides, keep track of maintenance and reach your goals with activity tracking.

Plays well with others

Pairs with Strava and Komoot to automatically log your rides across different apps.

Who is TQ?

TQ is a hard hitter in the e-bike world here to refine and redefine the way we ride. Delivering the best of both electric and traditional bikes, TQ’s harmonic pin ring transmission comes in lighter, quieter and smaller than most other e-bike drive units on the market. Wherever you roam, its assist feels natural and keeps you at one with the ride.

Formed in 1994 as 'Technologie in Qualität' in the blue lake land of Bavaria, TQ has grown from two founders to a team of over 1,700 employees across 14 locations, with a passion for innovation. Firmly established as one of Germany’s largest and best electronic product specialists in the fields of robotics, embedded systems, automation, medical technology and aerospace. You’ll find TQ in the moon-rover and robots performing surgery – systems that need to be equally precise and dependable.

TQ embarked on the e-bike journey as long ago as 2008 and has been building the passion, expertise, hardware, industry connections and plenty of ride time to prove it all out. In short, TQ is your riding buddy who can hold its own with the best while also articulating the subtle nuances of riding to the most minute detail.

Creating a system this new and this different took heaps of collaboration and a whole lot of prototypes. Throughout the development process, Germany-based TQ and US-based Trek worked exclusively together to fine-tune the HPR50 transmission system for a ride feel that’s unlike anything cycling has ever seen.

Made by bike people passionate about finding a better way to ride, the HPR50 provides nearly invisible assist that feels like a hand at your back on steep climbs and stays nimble and natural whether weaving down steep canyon roads or through technical trail terrain.

Shop bikes with TQ-HPR50