What’s currently the best eMTB motor? Is Bosch still considered the benchmark, or is it time to move on and look at other factors? What we know for sure is that the motor is the heart of any eMTB and has a decisive impact on riding dynamics and performance. However, there are still many myths and half-truths surrounding electric motors.

When taking a closer look at some of the most popular eMTBs you’ll come across the same five brands over and over: Bosch, Brose, Panasonic, Shimano, and Yamaha. There is also an exciting motor on the market produced by TQ which is not yet popular amongst manufacturers, but will surely cause a stir in the near feature. Over the years we’ve tested every single motor on dozens of different bikes, munching thousands of kilometres on hundreds of different trails and accumulating endless hours of usage. This gave us more than one opportunity to carefully analyse and consider all of the advantages and disadvantages of each motor.

  Each motor has a unique character and distinguishes itself from the competition by far more than just its power.

What’s the most powerful motor on the market?

If this is the one aspect you’re interested in, the answer is simple: the TQ 120S. With its massive torque of 120 Nm, this full-blooded Bavarian power-pack smokes the entire competition. Not many brands are using it just yet, but we’re sure this will change later on this year.
Second place goes to the brand-new Brose Drive S, which finally managed to overtake the Bosch Performance CX and Shimano thanks to its recent update. Generally speaking, all motors have more than enough power to climb even the steepest of hills. However, there is more to motors than just raw power.

Power is nothing without control

Spinning wheels are not just an issue for cars, as eMTBs have this problem too – maximum power doesn’t get you anywhere if it’s not properly transferred into the ground. Especially when starting up or riding on technical terrain, the power delivery of a motor needs to be both consistent and not overly vigorous. The motor that does this best is the Brose Drive S, closely followed by the Shimano STEPS E8000 in “Trail mode” and the Bosch Performance CX in “eMTB mode.” The Yamaha PW-X pushes forward powerfully from the first pedal-stroke, making starts on steep terrain much more pleasant. On loose terrain and steep gradients we recommend reducing the support level of the Yamaha to prevent the rear wheel from spinning. Despite its enormous power, the TQ 120S is surprisingly easy to modulate. In slippery conditions and on steep starts we still recommend reducing the support level.

Permanent headwind over the 25 km/h limit

There are motors which seem to be affected by drag (or a “permanent headwind”) when riding above the 25 km/h limit or the motor is switched off. This is especially noticeable with the Bosch Performance CX and Panasonic X0. Their internal gears drag and create a consistent loss of power. The only motors without any drag are the Brose and the TQ. These give you the same feeling you get when riding a classic mountain bike, even at speeds above the 25 km/h limit – with the exception of the extra weight of the bike. A slight dip in power is noticeable on both Shimano and Yamaha motors, but it’s still a lot less than with the Bosch.

Diesel or petrol?

Obviously, none of the motors run on fossil fuel. And still, the analogy comes in handy when comparing the performance of different motors, especially when talking about elasticity. Both the Panasonic and the Yamaha PW-X motors remind us of diesel engines, pulling strongly even at low revs. But once you pedal harder – to build up speed before a steep climb for example – the Yamaha runs out of steam. The Bosch, Shimano, and TQ are clearly better at this, providing for lots of power in a wide cadence range, whilst Brose have significantly improved their new version of the Drive S. Having said that, the Brose still performs most efficiently at a high cadence.

The motor hugely affects the handling of a bike

The motor hugely affects the cornering, control, and overall agility of an eMTB, the main reason being the size of the motor rather than its power output. The compact Shimano motor gives developers and engineers the most freedom when designing frame geometries, which explains its popularity with bike designers and engineers. On top of that, it’s a whole kg lighter than the big Bosch Performance CX, which also requires considerably more room for installation and thus limits both the geometry and the positioning of the bearing points. Brose and TQ give manufacturers plenty of freedom, but are still not that popular.
Even the best motor is totally useless if it’s not harmonising with the whole concept. This is why integration is one of the most important aspects engineers and designers have to consider when coming up with a design.
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How many support levels should a motor have?

In an ideal world, the motor would automatically adapt its power output to the current riding situation. Currently only the Shimano (Trail mode) and Bosch (eMTB mode) offer this function. Depending on pedal force, the motor releases different amounts of power, allowing a single mode to cover the same range that other motors would use several modes for.
This automatic mode allows you to focus more on the trail and less on the technical side of the motor. Still, a wider selection of support levels has its advantages: it allows you to save battery by riding in the weakest mode when possible. With their five modes, the TQ and Yamaha PW-X offer the most support levels.

How far does a fully-charged battery get you?

The amount of climbing you can do on one charge depends on many factors. However, it doesn’t take an engineer to work out that more power needs more energy. Depending on your weight, riding style, cadence, the terrain you’re riding on, the support level you’re using, the capacity of your battery, and many more factors, you can expect to squeeze between 700 and 2,000 meters of climbing out of a single battery charge. Currently all bikes with a Bosch motor feature a battery with a 500 Wh capacity. Other manufacturers, on the other hand, offer batteries with capacities ranging between 350 and 770 Wh. These values are nominal: in reality there can be fluctuations even within the exact same models. Due to the huge number of parameters, it’s impossible to come up with a general rule for battery range and capacity and tell you how far you’ll get with a fully-charged battery. If you’re thinking of getting a spare battery for long rides, you should be aware of its dimensions: some batteries are simply too long to fit into conventional backpacks. In this case, the external batteries from Shimano and Bosch are the ideal option.

Full info versus minimalistic design – the display dilemma

When it comes to displays, bike manufacturers have the choice. Almost every motor supplier offers a number of options and different sizes. For their Brose motor, Specialized dispense with a display altogether and rely on a minimalist charge-indicator placed on the downtube. You also have the option of sending all of the most important data via Bluetooth directly to an external device such a Garmin or a smartphone. With their high-resolution display mounted behind the handlebars, Shimano currently offers the best compromise between integration, legibility, and protection. Shimano also offers a very intuitive remote system which derives from a Di2 shifter and allows you to switch between support levels.

Symphony or rock gig?

This might look like a small detail, but the sound of a motor is crucial to many riders. It’s no surprise that sound designers spend hundreds of hours working out the perfect pitch of a closing car door or the signature growl of an aggressive V8 engine. When we talk about eMTBs, a quiet (or even soundless) motor is considered to be pleasant. In this matter, the Brose motor sets the benchmark even though it is still subject to fluctuations. (That’s why on some bikes you can hardly hear it, and on others you can hear a light buzzing noise.) Depending on the bike’s speed and the resonance of the frame, Bosch, Shimano, and Yamaha develop relatively high noise levels.

Did someone say walk-assist?

After the first tests were carried out a few years back, the walk-assist mode almost sunk into oblivion – that’s how badly it worked and how difficult it was to reach! Shimano wanted to prove they could do it better and revised both the ergonomics and the power-side of it. Brose and Bosch have improved their own systems too, while TQ‘s walk-assist version is alright. In reality, however, we’re still not using this feature very much since most climbs can be ridden or because the climb is so steep and technical that even the walk-assist wouldn’t help.

A matter of software

Hardly a day goes by without your smartphone asking you to update the apps and operating systems. In our digital world it’s the software rather than the hardware that makes the difference – and eMTBs are undergoing the same development. Motor manufacturers are regularly releasing software updates and constantly improving the performance of their motors as a consequence. Bosch recently presented the eMTB mode for their popular Performance CX motor, which will eliminate the need to change the levels of support while riding offroad. Brose and Shimano offer consistent software updates too. As clients we should keep up to date by regularly looking for possible software updates. We can do this either by referring directly to our dealer or by checking the available smartphone apps.

Service

If you have an issue with your eMTB motor or simply need to get it serviced, your certified dealer should always be your first contact. Certified dealers follow special training programs issued by motor and bike manufacturers and are authorised to carry out a number of basic repairs. With more complex issues or serious faults, your motor will typically be sent back to the manufacturer. Waiting times can vary depending on the season and workload. For software-related issues and updates, once again your dealer is your first point of contact. This leads us to one major consideration: when buying your new eMTB you should consider the competency and know-how of the dealer and not just the price of the bike.

Which motor is the best?

If we were exclusively looking for power, the TQ 120S would be the undisputed winner. However its sheer power is difficult to modulate and eats through a lot of energy in the higher support levels – plus not many manufacturers are using it at the moment. The Yamaha PW-X churns out decent amounts of power at low cadence, but eventually runs out of steam when riding at high cadence. Its turbulent nature in standing starts is not to everyone’s liking either.
The Panasonic is a very reliable motor, but its performance loss at a high cadence is irritating at best and the display integration still needs more sorting.
The Bosch Performance CX is currently the most common motor on the market and has repeatedly proven its capability over the years. Thanks to its updated software and the progressive eMTB mode, it is now even better equipped for all off-road scenarios. Unfortunately, its large dimensions and the noticeable drag above the 25-km/h limit is still a major drawback and represents a serious challenge for ebike designers.

Shimano STEPS E8000 | 70 Nm | 504 Wh, Custom
Brose Drive S | max. 90 Nm | 400-770 Wh

Shimano’s STEPS E8000 motor offers the fewest compromises and suits a wider range of applications. Its intuitive operation system and well-balanced power delivery (especially in Trail mode) are truly pleasant – plus the compact design and light weight are the ideal prerequisites for manufacturers to design the perfect eMTB.

The brand-new Brose Drive S motor offers the most natural and controllable ride. If its predecessor was lacking power, the updated version of the Brose motor stands right behind the TQ motor. On top of this, it runs very quietly, can be finely modulated even in the higher support levels, and presents virtually no resistance at speeds above 25 km/h.

However, the motor is only half of the story. Factors such as geometry, suspension, and spec of a bike are the keys to a comfortable, safe, and pleasant ride. When deciding on a bike you should consider all of these decisive factors carefully.

About the author

Christoph Bayer

Christoph loves to be kept on his toes – both on the bike and in his role for the E-MOUNTAINBIKE Magazine. He’s known as the guy in charge of the magazine and masquerades as both its editor and photographer. You’ll usually find him tearing up the mountains on his bike, soaking up the flow or tackling technical, narrow trails.