Electric mountain bikes have come a long way in the past decade, with the industry standard for full-power models settling on a mid-drive motor with a down-tube integrated battery that can churn out in excess of 85Nm of torque.
Although an already competitive market, it has now got a new contender in MAHLE.
Well-renowned in the electric road bike market with its hub-based motors, the German conglomerate – which has more than 100 years' expertise of mobility innovation – has now turned its forward-thinking approach to the world of eMTB.
The result is the M40 – a lightweight complete system that starts at only 5kg (with the 534Wh iM5 battery) but punches way above its weight, laying down 105Nm torque and 850W peak power.
Its appeal extends beyond its brawn, though.
Instead of steamrolling everything in its path, the drive system works intelligently with the rider. It enhances their physical abilities rather than overshadowing them to provide a natural riding experience that unlocks possibilities – whether that’s riding further, climbing higher or tackling more technical terrain without losing that inherent connection to the trail.
It manages this through a suite of intelligent assistance technologies that help amplify every ride.
From traction control to smart assist, a MAHLE SmartBike Systems engineer explains how once you've experienced these technologies, you’ll wonder how you ever managed without them.
Traction control
A form of traction control has been commonplace in cars since the 1980s, but its application in electric mountain bikes – where slippery or low-grip terrain combined with a heavier bike can make progress difficult – has been limited to date.
The M40 looks to solve these issues thanks to a combination of speed sensor, motor data, torque sensor and cadence information.
“To prevent traction loss, the system regulates the motor torque in real time to ensure the resulting torque at the wheel does not exceed a defined threshold, reducing power spikes that cause wheel slip,” says the MAHLE engineer.
When that threshold is met, the system’s control algorithm compensates power delivery, smoothing output at the wheel. It’s instantaneous, too, with the rear wheel’s speed sensor measuring its position 84 times per rotation.
“Combined with motor signals and rider torque and cadence data, we can reliably identify traction losses and determine from their frequency whether the terrain is slippery,” the engineer adds.
Smart Assist (automatic mode)
In addition to its three modes of assistance – Level 1 (100%), Level 2 (200%) and Level 3(400%) – the M40 also has a Smart Assist mode, where the system will determine the amount of power a rider needs based on analysis of their power, bike speed, selected gear (certain cases) and terrain gradient. This means constant tweaks, regardless of changes in gradient or trail type, and no more manually cycling between modes.
"Receiving the power you need in every situation makes the ride significantly more satisfying, fully recovering the feeling of muscular pedaling while enabling greater capabilities thanks to the assistance,” says the engineer. “Additionally, it increases range by optimising battery consumption.”
It’s not a one-size-fits-all approach either, and riders are able to customise the Smart Assist mode via the app or HMI, tailoring the assistance ratio, maximum power and acceleration to their specific needs – whether that’s a maximum effort session where the bike rides almost like an acoustic bike or maxed out for unparalleled comfort.
The Assistance Ratio can also be configured via the app, the Trio Remote (handlebar controller) and the Head Unit + (top tube display).
The Assistance Ratio can be adjusted from 50% to 600%, while the fine-tuning range available in the app and the Head Unit+ is 50% to 150%, with 100% set as the default (standard).
For example, if you are in Level 3 and want an Assistance Ratio of 400%, the setting in the app or Head Unit+ should be at 100%. This means the Assistance Ratio can be balanced between 50% and 150%, with 100% as the default value.
Auto Hold
The M40 isn’t focused solely on providing support in the form of power, but also has some smart safety innovations up its sleeves. Its Auto Hold feature takes information from the HMI accelerometer, speed sensor and torque sensor.
It then applies a motor brake, meaning the pedals remain locked and the bike stays in place, similar to holding the brake. This enables the rider to remain stationary without needing to keep a hand on the brake lever.
"The system detects the slope, confirms that the bike is stopped, and when the rider steps on the pedal, it engages the rear brake automatically, indicating the function on the display,” says the MAHLE engineer.
Useful for when stopping on steep, technical slopes, it enables the rider to remain stationary and focus on the task at hand without also having to contort themselves to hold the brake levers.
Plus, when they’re ready to commence climbing again, the Auto Hold is paired with a button-free start-assist feature that provides a small boost with the first pedal stroke, helping them get their second foot on the pedal.
"An extra impulse is provided at the start, allowing the rider to maintain balance without difficulty,” the engineer explains.
Dynamic Overrun
At the opposite end of proceedings, the M40 helps with another boost when a rider stops pedalling – helping to overcome technical climbs without striking the pedals on common obstacles such as rocks, steps or logs.
It doesn’t automatically happen whenever cadence dips, though, and adapts to the conditions and the rider input, hence why it’s called Dynamic Overrun.
“Overrun provides the confidence and momentum needed to tackle technical climbs and enables each rider to overcome challenges that previously felt impossible.“
"Thanks to the speed and rider‑torque sensors integrated into the bike, along with our control algorithms, we can determine the necessary power for each situation and adapt the bike’s response to the user’s input.”
As with all of MAHLE’s other intelligent assistance technologies, though, it’s designed to enhance rather than eclipse the experience, providing intuitive support instead of over-engineering that takes away from the joy of riding a bike. It can be configured to taste and even deactivated completely if there’s no need for the feature in a rider’s typical riding terrain.
