Correctly Choosing Your Ebike Motor

Although ebike motors in Europe can’t legally deliver more than 250W without license plates, their torque, functioning, noise, and levels of assistance can significantly vary.

Last update 07/10/2024

There is plenty of choice for motors on the e-bike market

We hope we are not skipping your favorite motor. Although we don’t pretend to be exhaustive, we hope that this post will let you grasp ebike motors basics, enabling you to better choose.

Battery capacity and torque are paramount

Since the scope of this post is only 250 W motors, the two most important factors are battery capacity and torque. Of course, more torque implies more electric energy consumption.

Choosing the right battery for your motor

The more a battery is powerful, the heavier and more expensive, but also the longer the range it allows. Therefore, bigger and more powerful is not always better. It all depends on the usage. If you are to ride hardly ever longer than an hour, using medium levels of assistance, 350 Wh will be largely sufficient. On the other hand, if you often challenge steep climbs for longer trips, you’d better choose a battery with at least 600 Wh, all the way up to 900 Wh. Take into account that the higher the torque of your motor, the more it will consume energy. If you privilege agility over assistance power, using your muscles rather than massively relying on your motor, even a light 242 Wh battery, like that of the MahleX 20 drive, would be enough. A range extender is a good option, providing more flexibility, inasmuch you carry its extra weight, an average 1.8 kg for 250 Wh, only if you need it. High-quality batteries, like those of established brands, last longer and deliver power more homogenously even when working at low charge levels or in cold and hot temperatures.

Discerning the right amount of torque

Torque is expressed in Newton meters. Isaac Newton discovered gravity; indeed, the bigger the torque, the stronger the motor assistance for climbing. torque is the capacity of a levy, like a crank arm, or a piston, to rotate any wheel, like a chain ring. E-bikes motors can have a torque going from the 23 Newton meters of the MahleX 20 to the 120 Newton meters of the TQ HPR 120 S. Many high-quality e-bikes offer 85 Newton meters of torque, equivalent to that of a small city car! The weight of a motor is proportional to its torque, going from the 1.365 kg of a MahleX 20 to the 2.8 kg of a bosch performance CX, sporting 85 Newton meters of torque. Some motors with 85 Nm weigh more than 3 kg, and those with more than 90 Nm, up to 120 Newton meters, weigh around 4 kg. Again, your choice depends on your riding habits and demands. For instance, for commuting on hilly roads, more torque is better, even if that involves three or four additional kilograms for motor and battery together. For mountain biking, the more you intend using your muscles, the better choosing a lighter motor with less torque.

Some of the most common e-bike motors in Europe

Motors for light e-bikes

Bosch Performance SX

Quite an innovation for Bosch. Instead of focusing on performance and power, this motor excels for versatility, ease of use and harmonious, pleasant assistance. Not that other motors from Bosch lacked these qualities, but this one is the state-of-the-art. With 55 Nm of torque, it weighs only about 2 kg and sports a power to weight ratio of 300 watts per kilogram. The rather narrow Q-factor of 160 millimetres and a noticeably lower pedalling resistance support the famous “natural” pedalling. Pedaling resistance has been one of the very few weak points of Bosch motors in the past. Peaking at 600 watts, this silent, discrete engine features a new assistance mode, the Sprint, which calibrates its support according to your pedaling cadence.

TQ HPR 50

Quite light, at 1.850 kg, the TQ HPR 50, with 50 Newton meters of torque, is extremely small. This motor is very silent, offering one of the best torque to weight and dimensions ratio on the market.

Fazua Ride 60

The most powerful in terms of torque of the very Iight motors, the Fazua Ride 60 weighs only 1.96 kg for 60 Newton meters of torque. Very small and extremely silent. You can take it off, together with its battery, turning your e-bike into a normal bike.

Mahle X20

The Mahle X20 hub motor itself weighs only 1.399 kg, being the lightest of all, with 23Nm of torque. Together with its 242Wh  battery, wiring, controller, and head unit, it weighs an astoundingly low 3.2 kg. It bundles the most modern technologies into the drive. Basically, it is a search for a system that gathers information from the way you ride and, with the help of the collected knowledge, highly individualises the support of the motor.

Mahle X35+

Unobtrusive, slim and light. The intube battery and the control units together weigh only 3.5 kilograms. Of course, in terms of power, the Mahle drive with its motor output of 250 watts, the torque of 40 Newton metres and the 245 watt hours of battery capacity is far away from the Bosch power. Indeed, the Mahle X35+ is for manufacturers who want to integrate a drive system into sporty bikes that don’t look like ebikes at all. For a good reason, the list of Mahle’s cooperation partners mainly includes illustrious names from the racing bike sector: Colnago, Pinarello, Bianchi, Orbea.

Maxon Bike Drive Air

It weighs only 3.5 kg together with its 250Wh battery. Ideal for very light e-bikes, it offers no resistance when turned off, giving your eBike the feeling of a regular bike.

Specialized SL 1.1

Relatively light at 1.95 kg, it delivers only 35 Newton meters of torque. Compare it with the Fazua Ride 60. Not particularly silent, it offers excellent regulations through its application and control unit.

Shimano EP 8 RS

Its hardware is identical to that of the Shimano EP 8. At 2.65 kg, being the heaviest of the light e-mountain bike category, it delivers 60 Newton meters of torque, and is more silent than the EP 8.

All around ebikes motors

For daily commuting or steep climbs, more torque is needed, although that requires more weight for motor and more powerful batteries.

Bosch Performance Line and Performance CX

Extremely precise and smooth, it’s almost unbeatable when it comes to harmonizing leg power and assistance. The Performance Line, particularly silent, delivers 65 Nm of torque, and 75 Nm in the Smart System version. With 85 Newton meters, the Performance Line CX, weighing 2.8 kg,  enables easy starting even on steep climbs, and accelerates quite promptly. It’s a little noisy, although only in its early versions.

Bosch Cargo Line

Bosch adapted their Performance CX already sporting a sound 85 Newton meters of torque to render it even mightier, thus reaching state-of-the-art level for cargo eBikes. Bosch has specifically designed its special cargo riding mode for the enormous stresses and strains of riding with a high payload, which are particularly noticeable when starting off.

Bosch Performance Line CX Race

Even more powerful, even more abrupt, even higher revs. The greater part of the development work probably went into the software. The result is a completely new support level – the race mode. According to Bosch, the assistance is even more direct than in the existing modes. In addition, support is provided up to 400 percent of your own pedal power. The “normal” Bosch Performance Line CX stops at 340 percent. Weight: approx. 2.75 kg, 150 g lighter than the Performance Line CX.

Bosch Active Line and Active Line Plus

It was conceived for the city, and is silent and smooth. Its 4o NM of torque (50Nm for the Active line plus) are sufficient on flat itineraries. Should riding uphill be frequent, a Performance CX would be highly appreciated.

Shimano EP5

Shimano EP800/EP801

Delivering 85 Newton meters of torque, this motor is relatively light, 2.6 kilogram, and rather compact. It’s compatible with several kinds of batteries, enabling its integration in different e-mountain bike frames, what allowed its adoption by many manufacturers. It works quite differently from the Bosch performance CX, since it requires more inputs from the rider in order to deploy all its power. It’s nevertheless appreciated by those who like a more active role of their legs. EP801 combined with DEORE XT Di2 or CUES Di2 shifting offers innovative FREE SHIFT technology, which allows to quickly shift gears at any time, even when the pedals are stopped. It can support AUTO SHIFT for automatic shifting.

Shimano E7000

Only 60 Nm of torque, fluid and smooth, although strong at the start.

Shimano E6100

Versatile and silent, 60 Nm of torque, conceived for city ebikes. Weight: 2.88 kg.

Shimano EP600

A little heavier, with 2.9 kg, but also cheaper, still 85 Newton meters of torque and AUTO SHIFT or FREE SHIFT, and DEORE XT Di2 or CUES Di2 rear derailleur compatible. SHIMANO EP600 delivers EP801-level performance at a more affordable price. Better suited for city and trekking than for MTB.

Shimano E5000

Silent, barely 40 Nm of torque, light with 2.5 kg, conceived for city ebikes, it’s the lightest and cheapest of the range.

Brose Drive S Mag

It’s one of the most silent of its category, thanks to its belt transmission. It’s particularly powerful at low pedaling cadences.

Some Bafang Motors, from their wide range:

To yhe best of our knowledge, it has yet to be proven that Bafang quality can compete with the likes of Bosch, Yamaha, TQ, Shimano, Brose, Mahle, etc.

• M820
  Good weight to torque ratio, 2.3 kg for 75 Newton meters. Even 95 Newton meters for a short time at peak are declared for the Bafang M820. Its case is made of magnesium, which effectively dissipates heat. It also attenuates the vibrations. Maximum extended cadence support of 120 rpm.
• M620
  2.3kg 75Nm (max torque) for a maximum extended cadence support of 120 rpm.
• Just two of their numerous hub motors:
  H610 65Nm torque for 4.5kg – H700, 40Nm of torque for 3.2kg, lightweight and compact, 136 millimetres in outer diameter.

Yamaha PW-ST

Weight, 3.4 kg. Rated Output, 250 W. Max. Torque, 70 Nm. Assist Mode, 4 modes.

Yamaha PW-SE

Weight, 3.5 kg. Rated Output, 250 W. Max. Torque, 70 Nm. Assist Mode, 4 modes.

PW series S2 for Speed Pedelec

Max. Torque 75 Nm; Weight 2.85 kg; Max. Assist Speed 45 km/h; Assist Mode 4 modes.

Yamaha PW X3 and PW XM

The PW X3 sports 85 Newton meters of torque and is quite similar to the Bosch Performance CX, weighing only 50 g more. The PW XM is 250 g lighter, at 2.6 kg, thanks to its magnesium case. It has got improved bearings and fins that, together with the magnesium case, help dissipate heat.

Yamaha PW-CE

Yamaha’s entry-level mid-motor  It has mainly been deployed in urban ebikes. With 50 Newton metres of torque, it weighs 3 kg.

Yamaha PW-C2

Updated (in 2023), bettered version of the PW-CE. It generates 55 Newton metres of torque (10% more than the PW-CE) weighing about three kg.

ZF Centrix

ZF, with more than 160,000 employees worldwide, is a giant car parts manufacturer. They now have launched an impressive ebike motor weighing barely 2.5 kg, impressively small with 88 mm of diameter, sporting a whopping 90 Newton meters of torque. A detailed review of the ZF Centrix here.

Polini E-P3+, E-P3+GP and E-P3+MX

Light, powerful and compact, the Polini E-P3+ motor has one of the smallest lateral encumbrances in its category and is available in 3 versions: the E-P3+ model that delivers 75 Nm torque (for all terrain or trekking bikes), the GP model with 80 Nm torque (designed specifically for road and gravel bikes) and the MX model (specifically for MTB) with 90 Nm torque for the most demanding customers. They alla weigh 2.950 g, with 250W and a peak power of 500W for the  E-P3+ and a peak power of 600W fro both the  E-P3+GP and E-P3+MX.  Five levels of assistance for all.

Panasonic’s GX ultimate

With 95 Nm of torque and a weight of 2.8 kilogram, it proves once more that torque and weight are strictly correlated. It deploys its power quite strongly and constantly, even at lower cadences. Its design is compact and particularly narrow, which enables a small Q factor. A reduced distance between pedals avoids knee problems, grants more efficient pedaling, and also lessen the risk of hitting obstacles on trails.

Sram Eagle Powertrain

Based on the Brose  S Mag, delivering a gorgeous 90 Nm of torque, it shines with the impressive technology of the whole Sram Powertrain, For instance, you enter your preferred cadence into the system and the ebike drive does the necessary gear shifting. Only Auto Shift does this with derailleur gears. Or, it displays even your power output in watts.

Powerful eBike motors

Always with 250 W, some motors offer an impressive torque.

Bafang M510

With 95 Nm of torque and weighing just 2.9 kg, this motor, especially conceived for eMTBs, sports the best weight to torque ratio across the board. Moreover, it delivers its pedalling assistance up to  high speeds of 120rpm.

Bafang M600
A whopping 120Nm max. torque, just 3.9kg, for eMTBs and eCargo bikes.

SACHS RS

With 110 Nm of torque, this German motor weighs 3.6 kg. It’s very powerful, but it’s not easy to master especially on steep climbs, because it delivers its power depending more on the cadence than on the pressure exerted on the pedals.

Rocky Mountain Dyname 4.0

Quite silent. Motor weight: 3kg, outstanding weigth to power ratio | Modes: Eco, Trail, Turbo | Norminal power: 250 W | Peak Power: 700W | Torque: 108Nm

TQ HPR 120 S

You can appreciate its whopping 120 Newton meters of torque on steep paths, albeit it being also the heaviest with its 3.9 kg. With such impressive power, one should better be careful when starting, to avoid that the ebike wheels up or that the rear wheel sleds. That’s why Haybike has developed a special sensor for this motor.

Motors with embedded gearbox

We extensively wrote about those, notably the Effigear and the Pinion MGU. We tested the former, which shifts automatically and smoothly according to the terrain, for instance when you start climbing, enabling even shift at standstill, or to shift multiple speeds at once, even with lower gears. The Pinion MGU is not second to Effigear, to the best of our knowledge.

Motor maintenance

Electric motors in general, and also eBike motors, require hardly any maintenance. Depending on the conditions of usage, they can easily ride more than 20,000 km without any maintenance. Nevertheless, some internal parts can wear off, especially bearings. For instance, riding in very hot or even very cold climate can accelerate bearings wearing off. That’s why Bosch offers maintenance kits for its models. Here’s one for Active and Performance Line drives from 2014, one for Bosch ActiveLine and ActiveLine Plus drives from 2018 and, from 2020, maintenance kits for Gen4 motors: Bosch Cargo Line Gen4 (BDU4XX), Bosch Cargo Line Speed Gen4 (BDU4XX), Bosch Performance Line CX Gen4 (BDU4XX), Bosch Performance Line Speed Gen4 (BDU4XX). Those include bearings protection rings and grease tubes.

Pictures: TQ, Fazua, Bosch, Brose, Bafang, Shimano, ZF, Yamaha, Specialized, Maxon