While Mahle might not be on the tip of ebikers’ tongues when it comes to considering which motor they’d like in their next bike, the introduction of the new M40 motor may change things.
That's thanks to some impressive performance stats – 105Nm of torque, 850W maximum power and a weight of 2.5kg.
Mahle isn’t the best-known brand in the electric mountain bike motor space. The brand is better known in the assisted road bike market, thanks to a range of hub-drive motors mounted in bikes from the likes of Merida, Bianchi, Wilier and Ribble. However, Mahle does manufacture the motor in the Specialized Turbo Levo SL.
As with the likes of Bosch, Gates and Magura, the bike division is only a small part of a large conglomerate, with Mahle’s technology extending far into the electric automotive world. Some 68,000 people work for this huge company.
The introduction of the M40 puts Mahle's flag in the electric mountain bike ground, and we’re excited to see which brands pick up this new motor.
Current partners are listed as "Abums, Labyrinth, Messingschlager, Sants and Titan Racing". However, we believe more will be announced at Eurobike 2025.
The M40 is a mid-mount motor (as per the majority of eMTB motors), comes with a pair of new batteries and features some interesting technology.
Mahle M40 stats
Key when it comes to ebike motor performance are the torque and power outputs.
DJI’s Avinox motor set the market alight with its impressive 120Nm and 1,000W max outputs, with updates and new motors from competitors clamouring to reach such figures.
However, it’s worth bearing in mind potential EU legislation could limit these figures down the line, with support from Bosch.
For now, Mahle’s M40 hits some high numbers. 105Nm of torque and 850W maximum power are not to be sniffed at, placing the new motor on the powerful performance leaderboard.
It’ll kick out up to 400% of assistance – if you put in 100W, it’ll add another 400W – up to that 850W max.
Its peak performance is delivered with a cadence of 90-120rpm, however, below this speed, there’s still plenty on offer.
The motor weighs in at 2.5kg – in line with the most recent full-power motors from other brands, thanks to its lightweight magnesium casing.
The M40 is said to benefit from Mahle's Decoupling Mounting System, which reduces the transmission of vibrations from the motor to the frame.
Cranks attach via the ETOR standard, enabling a wide range of cranks from the major manufacturers to be fitted.
Brands will have the option of the 534Wh iM5 battery, which weighs 2.5kg, or the heavier iM8, with 850Wh of capacity, aimed at those looking for an optimised range of up to 150km, or 2,500m of ascent.
Both batteries share the same form factor, so should fit in the same frames.
Keeping it rolling
There's quite a lot more involved in making a decent eMTB motor, namely how – and how consistently – the power is delivered.
Although it's not often mentioned, temperature control is important when it comes to ebike motors – getting them too hot by asking for consistently high power can degrade performance.
When this happens, motors can turn off, or drastically reduce their output until things cool down a little.
Mahle is keen to point out that its heat management systems should prevent this from happening.
When the temperature gets towards the limit, the maximum power is limited to 750W with the aim of lessening the chance of overheating, without drastically impacting the ride experience.
Perhaps more interesting are the internal sensors – and what they mean for current and future performance.
Inside the motor are various accelerometers, torque meters and gyroscopes.
There's also a rear-wheel speed sensor that has a high degree of resolution. With a 27.5in wheel, the system can detect your speed every 3cm of trail – thanks to 84 readings per revolution.
In contrast, if your ebike has a magnet mounted to the wheel or rotor, that's only reading your speed once per wheel revolution.
These sensors are able, therefore, to detect a large amount of data pertaining to what your bike is doing, and then adjust the motor's attitude to your power input accordingly.
For example, if the system detects the rear wheel suddenly speeding up while climbing, it's a fair assumption that the wheel is spinning and not gripping. Power can then be reduced to regain control.
On descents, if the bike is leant over, the kick of any power input can be reduced to prevent the loss of control.
Likewise, the motor's 'Dynamic Overrun' alters how much the motor continues to pull the chain round once you stop pedalling, depending on the speed and whether you're climbing or descending.
Doing this is said to improve the motor's climbing performance.
Mahle tells us it is continuously monitoring user data to improve the software and thus performance.
For example, in time, it should be able to tell the difference between a bike that's looping out by accident on a climb, and when someone is intentionally popping a wheelie.
Three modes will be on offer, with Level 1 being moderately chill, and Level 3 offering it's full punch.
Level 1 will give 100% assistance - doubling what you put in. Level 2 will triple it, with 200% assistance, while Level 3 gives you up to the 400% assistance, maxing out at 850W.
Extra assistance
The walk mode is engaged by holding the 'down' button on the wireless on-bar controller. This spins the cranks to rotate the rear wheel.
Additionally, there's a hill-start function. By gently pushing down on the cranks while the bike is facing uphill, the motor engages and prevents the bike from rolling backwards.
The neat on-bar Trio Remote, which features LED status displays, is supplemented by a 1.9in top-tube mounted head unit and display, which shows a multitude of data via its colour screen. A second Trio Remote can be added to the bar for additional functionality.
Data is customisable, while additional data can be found in the accompanying app.
While OEMs (bike brands to you and I) will have around 100 customisable parameters, to match the motor's performance to their individual bikes, riders will also be able to tweak a second, narrower layer of motor performance.
Mahle has a suite of additional items in its ebike ecosystem, including neat wall-mounted chargers, mirroring those in the automotive world.
Mahle M40 motor initial impressions
I only spent a little while riding the motor, which was fitted to a frame that Mahle had built specifically for the launch – expect more partner brands to be announced at Eurobike 2025.
Much like DJI's Avinox, what is immediately obvious is how reactive the motor is to human and trail impacts.
While it's a cliche, it has a very natural feel, with easily controllable power to the rear wheel.
At those higher, ideal cadences, the power delivery is punchy and smooth, easily powering you up steep, loose and technical climbs.
The overrun doesn't boost you uncontrollably into sections you want to take more care in – rather, it supplements what you're trying to achieve in a subtle manner.
At lower cadences, there's still ample grunt to get you up steep pitches. In fact, on the steepest pitches, I used lower cadences to keep the bike as stable as possible, rather than pedalling manically at a high rate and relying on the torque to get me up.
During descents, I didn't find the motor pushed me beyond speeds I wanted to be at – the overrun is subtle and the kick of power when I did put pedal strokes in was smooth.
The hardware seems solid. The remote controller is well-shaped and doesn't take over the bar, while the feedback through the buttons is ample.
The screen is bright and readable in sunny conditions.
I'm excited to see which brands pick up this motor. It's a crowded space, and it's difficult to think of bikes that are due a refresh. However, whichever bikes come equipped with the M40 shouldn't find their performance compromised by the motor.
