TQ HPR40 On Review: Stealth Motor for Drop-bar Bikes

For a long time, e-road bikes felt like a contradiction in terms: too heavy, too bulky, and sluggish once you crossed the 25 km/h threshold. Now TQ are aiming to change that with the HPR40 – an ultra-lightweight, near-invisible motor designed specifically for drop-bar bikes. We put it through its paces to find out whether the HPR40 lives up to the hype.

Stealth was the clear design brief here – and the HPR40 delivers just that. Built specifically to meet the demands of road and gravel bikes, the Bavarian manufacturer now splits their motor line-up for the first time. Until now, the HPR50 served as an all-rounder, appearing in everything from e-road bikes to eMTBs. But things are getting more focused: The new HPR40 is tailored for drop-bar bikes, whereas the HPR60 is geared toward urban and mountain bike use.We’ve tested both motors already – for the review of the HPR60, head over to our sister magazine E-MOUNTAINBIKE Magazine. For now, let’s dive into what the HPR40 has to offer.

The new TQ HPR40 motor at a glance

With just 40 Nm of torque, the HPR40 is one of the lightest and weakest mid-drive motors on the market. But that’s no accident. TQ intentionally pared the system back, fine-tuning it it for use in road and gravel bikes. The motor itself weighs just 1.17 kg. Throw in the 290 Wh battery and minimalist system components, and the total system weight lands at just 2.7 kg.

This opens up new possibilities: fully integrated e-road bikes with mid-drive motors tipping the scales below 10 kg – something previously considered near-impossible. And while the motor maxes out at a modest 200 watts on paper, that’s enough to catapult an averagely fit rider into power-to-weight zones normally reserved for the pros. The motor is barely bigger than a clenched fist and, according to TQ, boasts the highest torque density on the market. The compact, round shape allows for a clean integration into the bottom bracket area. Like a stem clamped to a steerer, the motor is fixed to the frame with two mounting bridges, which simplifies removal and any maintenance work.

Internally, the HPR40 relies on TQ’s proprietary Harmonic Pin-Ring gearbox, which allows for a more compact design and, according to the brand, highly efficient power transfer with minimal loss. The gear ratio has been tuned for quiet operation and optimal performance at typical road bike cadences – between 75 and 95 rpm.

A built-in torque and cadence sensor in the bottom bracket adapts motor output to your pedalling input and can transmit the data to your head unit if needed. Unlike many other mid-drive motors, the HPR40 connects the crank directly to the chainring. This means when you backpedal, the chain moves with it, and on the road, the pedal-to-wheel power transfer feels even more direct.

Battery and range extender of the new TQ HPR40

The motor draws its power from a sleek 290 Wh battery integrated inside the frame. If your ride demands more, you can extend the range by 160 Wh using a range extender that mounts like a standard 500 ml bottle and weighs 900 g. How far that’ll actually take you? We’ll get to that in the ride impressions below.

The TQ HPR 40 display and remote control

Matching the minimalist design of the system, the remote is cleverly integrated into the end of the handlebars. Nearly invisible, it blends perfectly into the cockpit with a clean and functional look. A small LED light strip provides battery status and current support mode. It saves space, avoids clutter and ditches the typical bulky e-bike aesthetic – a win for style-conscious riders.

One standout feature: the support modes can be controlled using the auxiliary buttons of your electronic shift levers. This means that you can toggle modes or activate lights directly from the shifter without needing a separate remote. TQ went for maximum compatibility too: the system includes multiple ports for powering external devices like integrated front and rear lights straight from the main battery. On our test bike – the Canyon Endurace:ON Fly – the entire lighting system was integrated and powered from the TQ battery, as was the electronic drivetrain.

Manufacturers can also wire in charging ports for your head unit, radar tail lights or even a smartphone. The internal control unit housed in the handlebars provides two additional outputs for accessories – a smart touch that expands the HPR40’s potential and simplifies integration. TQ haven’t just built a motor, they’ve created a complete system for modern, connected drop-bar bikes.

TQ E-Bike App

Speaking of connectivity, the HPR40 pairs with the TQ E-Bike app via Bluetooth. Just like the motor itself, the app is refreshingly streamlined – no gimmicks, no bloat, just a clean, focused interface.

You can view key data like the battery charge status and ride metrics, but more importantly, you can set up rider profiles and fine-tune the three support modes. Adjust maximum power output, support intensity and pedal response to dial in the ride feel for long gravel adventures, fast road rides or laid-back evening spins.

Real-world test: the TQ HPR40 in action

Claiming a drop-bar e-bike looks like a regular road bike is hardly headline material in 2025. Sleek integration is now the standard. But TQ have raised the bar again – not just visually, but also acoustically and functionally.

The motor virtually disappears into the bike’s downtube. The removable cover can even be painted to match the frame. There’s no display on the top tube, no obvious buttons or bulky interfaces. Just a tiny LED indicator tucked into the bar end, barely noticeable even on second glance. Mode and light controls are handled via the shift levers, whether you’re running SRAM or Shimano. Alternatively, you can use the app or the button at the bar end.

But it’s not just about looks. The HPR40 is whisper-quiet, even under full load. The hum of your tires or the wind around your helmet will be louder. And then there’s the weight – historically the Achilles heel of many e-road bikes. But TQ are bringing the dream of a “normal” road bike with a stealthy motor support much closer to reality. The Canyon Endurace:ON Fly stays under the 10 kg mark with the HPR40, and with going full weight-weenie on components.

On the road, it rides naturally. Power transfer is direct, and the weight pleasantly balanced. Cruising at 30 km/h on rolling terrain – just like you would on a standard road bike – feels totally natural. The HPR40 doesn’t hold you back; it’s integrated so well that riding without support is genuinely enjoyable.

And that’s a big deal. Until now, e-road bikes were great for climbing with friends who are fitter than you, but once on the flat, the motor would cut out, and the extra weight would leave you working twice as hard to keep up. The HPR40 changes that.

On climbs, the assistance kicks in smoothly and fades out just as gently – no jerky transitions, no sudden cut-offs. Even in the highest mode, the support feels subtle. It helps, but it doesn’t take over. With a max assist of 200 watts, add in your own effort, and you’re comfortably powering up steep gradients – think double-digit percentages – and still feeling like you’re doing the work. Or push it harder, and you’re flying up climbs at 7 watts per kilo.

In short: the HPR40 is made for riders who want to earn their ride but appreciate a little boost when the road turns skyward. In our test, it was one of the most discreet, natural and seamlessly integrated e-bike systems we’ve ever ridden. In terms of sound, ride feel, power delivery and integration, it sets a new benchmark – and brings the dream of a lightweight, agile, near-invisible e-road bike tantalisingly close.

Climbing range test: how many vertical metres can you get with the TQ HPR40?

There’s little point quoting range figures for e-road bikes – after all, you’re usually above the 25 km/h limit on the flat, so riding happens mostly without motor support. The real question is: how much climbing can the battery handle?

We ran the numbers. Our test rider (72 kg) rode the 10.9 kg Canyon Endurace:ON Fly in the highest support mode, holding a constant 200 watts of personal power. The motor matched that output with a consistent 200 watts of assist. Result: after 1,217 vertical metres, the 290 Wh battery was empty. This equates to 23.83 Wh per 100 vertical metres – a solid result that shows the motor is working efficiently. Most importantly, the HPR40 maintained full power right up until the final percentage of battery – no throttling like with some other systems. That gives you confidence and control when planning big rides.

And of course, you’ll go further if you vary the support level. With a decent level of base fitness, 2,000 metres of climbing is well within reach using Eco or Medium mode. Add the range extender, and even more ambitious adventures become possible.

Who should take a closer look at the TQ HPR40?

The HPR40 is built for sporty road cyclists and gravel riders who want an e-bike that doesn’t scream “e-bike.” If low weight, stealthy integration and a natural ride feel matter to you, this system ticks all the boxes. Thanks to its great efficiency and balanced system weight, it’s just as suited to punchy climbs as it is to fast-paced flat rides – even above the 25 km/h limit. If you like riding fast on your own steam but want a hidden ace for the climbs, the HPR40 is your perfect riding partner.

Conclusions

With the HPR40, TQ took a major leap forward, delivering a motor that sets new standards. The blend of natural ride feel, efficiency beyond the assist cut-off and ultra-clean integration makes this compact mid-drive motor hard to beat. TQ aren’t chasing maximum power. Instead, they’re doubling down on discretion – and it’s exactly what so many performance-minded riders have been waiting for: an e-bike you can’t see, barely hear, but will definitely feel when you need it most.

More info at tq-ebike.com.

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Words: Jan Richter Photos: Jan Richter