HomeNews & FeaturesCommutingFactory Tour - The brose motor for 'premium' e-bikes

Factory Tour – The brose motor for ‘premium’ e-bikes

Berlin is a magnet; centrally located in Europe, it teems with history, culture and innovation. The city is home to thousands of start-ups, though the company in focus in this article, brose, is over a century old. While they can’t be classified as a start-up, they are still innovating after all of this time.

brose’s main business is in automotive parts; electric windows, seats, automatic doors, and other mechanical systems from brose are delivered to 80 automobile manufacturers and 30 automotive suppliers. Car companies and suppliers, however, are becoming increasingly interested in bicycles, particularly with the rapid growth of e-bike sales globally. As the cities become congested and society pushes for renewable energy, the automotive sector recognises the potential of alternative transport and personal mobility devices; e-bikes are a natural stepping stone.

At brose, they identified similarities between an existing motor they produce for cars and e-bike motors. From 2010, their exploration into e-bike motor production lead to prototypes and by 2013 product development of the brose e-bike motor was ramped up to begin manufacture directly in 2014 in Berlin.

I was welcomed into the Berlin factory by Tobias Bergmann and Cornelis Van Vliet, but only after passing security checks and a briefing that photography of the product was strictly verboten. The upstairs meeting room overlooks one of the halls with production lines. It isn’t as noisy as I expected; lots of diligent automated machines assembling parts, guided by humans who ensure that production runs smoothly. Tobias points out the area where the e-bike motors are being made and where later I will be able to observe them close-up.

Porsche ebike
Porsche premium e-bike with a brose motor


brose prototype ebike
Prototype e-bike with brose motor


brose prototype display
Display unit on the prototype brose e-bike


brose ebike motor frontplate
The brose e-bike motor front-plate can be customised


brose ebike motor
The brose e-bike motor from behind


What makes the brose motor so special?

If you are new to e-bikes, the e-bike you buy today will be far more advanced than e-bikes available two years ago. The motors and electronics are evolving to deliver riders a smoother and more natural ride. brose are a second mover in a market dominated by the Bosch mid-drive motor, and while the two motors are comparable in many ways, the brose has two significant competitive advantages.

Firstly, the motor unit is compact. For all mid-drive motors, the frame is built around the motor itself, and the brose’s smaller motor size allows the bike brand more freedom to design the frame to prioritise riders requirements (i.e. frame geometry). brose also let the bike brand create their own cover plates for the motor; the result is a better aesthetic integration and it’s no longer only a bike with a motor attached.

The second advantage is that once the maximum pedal assist speed of 25 kmh is reached, the motor is disengaged, like a freewheel. In comparison, other systems still have motor resistance above 25kmh when there is no power assistance.

If you analyse the technical specifications and compare the brose with Bosch and Shimano Steps, you could argue about the finer details and differences, but the real test is on the bike. I was able to take a Rotwild MTB for a test ride for some first hand experience. Before testing, however, I had the opportunity to go down to the assembly area to see the brose e-bike motors.

brose Berlin Tobias Bergmann
Tobias Bergmann at brose in Berlin


Just-In-Time production

brose looks after the complete assembly of their motor in Berlin, from wrapping the copper wires on the motor right through to quality assurance and testing. I counted ten main steps for the assembly of each unit; the workers select, check and position parts and control high tech equipment for automated tasks.

The entire brose production operates “Just In Time”, which means that motors are built and delivered as required to the bike companies, which saves stock-piling at both ends. The production can be scaled up or down and the workers are skilled to perform each of the steps (plus other assembly roles in the factory). During peak production periods, the assembly workers concentrate on single steps, while in slower periods one worker will guide the motor assembly across multiple steps.

brose Berlin ebike assembly
brose e-bike motor assembly (photo supplied)


Power me up

brose collaborates with another German company called BMZ who are the preferred partner to supply batteries to power the brose motor. While other batteries are compatible with the brose motor, the collaboration defines both companies as suppliers to the premium e-bike segment; the batteries and configuration can be customised to the needs of the bike brand.

Traditional battery packs for e-bikes are mounted onto a rear pannier rack or onto the downtube. It is becoming common place for bike brands to preserve the aesthetics of their bikes and conceal the batteries inside the downtube of the bike, though this also requires the designers to properly engineer the bike to ensure that this part remains structurally sound.

BMZ collaborate with the bike designers to create customised batteries, though Cornelis confirms that this option does come at a price. Smaller bike brands tend to opt for one of the standard solutions. One of the innovative battery integrations was undertaken by the German MTB brand Rotwild, who I also visited while in Germany and who have a completely removable down tube section housing the battery. You can read more about Rotwild here >

Cornelis Van Vliet BMZ batteries
Cornelis Van Vliet of BMZ works in collaboration with brose


brose display unit BMZ batteries
Cornelis shared their next generation prototypes for the display units


On the bike with brose

The simple way to explain the benefit of an e-bike is that it reduces the physical effort required to ride it and this makes cycling (with motor assistance) attractive for a much larger audiences. Providing the power to assist cycling is the easy part of the equation, the hard part is integrating it seamlessly so that bike riding feels natural, without the motor suddenly cutting in or out and making riding disjointed. The e-bike motor needs to provide power without detracting from the cycling experience.

E-bike motors are peppered with sensors which constantly analyse speed, cadence and torque. A good motor will evaluate the data and control the motor to create the effect of seamless pedaling.

brose Rotwild BMZ battery
Rotwild with integrated brose motor and custom BMZ battery


I was able to test-ride a Rotwild MTB with the brose motor, first in the factory car park and then along some of the bike paths. It was a pedelec with a maximum of 250 watts and power assistance while pedaling, up to 25 km/h. On a MTB it is easy to reach 25km/h on the bike paths, more-so with power assistance. I tested the three different power modes as well as the acceleration and performance of the motor at very slow speeds.

The Cruise, Tour and Sport modes each provide an increasing amount of power assistance. Cruise and Tour are rather smooth; the power assistance is noticeable while pedaling, though it is gentle rather than abrupt. The Sport mode however is a real booster and quickly fires into action propelling you forward. The Sport mode is obviously tuned to mountain bikers who need the raw power to get them back up the hills. The powerful Sport mode is not as seamless as the Cruise and Tour mode, for a city bike however it would still be a welcome boost for riders who want to power along.

To put the motor on trial, I tried cycling very slowly and having an irregular cadence. At low speeds the motor struggled to understand what I (as the rider) want to do – did I want to start or stop? It became more noticeable when the motor was kicking in or stopping. In context, however, it is also unrealistic that a rider would ride less that 5 kmh and pedal in such a fashion.

I had trouble detecting the typical whine of the electric motor usually associated with e-bikes and electric cars. This is good news of course, the brose is a quiet motor.


A growing market

As a second mover, brose has to compete against mid-drive e-bike motors from Bosch, Shimano Steps, Panasonic and Impulse. The challenge is getting bike brands on board. Specialized recently announced that brose was spec’ed for their premium e-bikes, which confirms brose as a premium solution. Other brands, such as the German BULLS and Spanish BH Bikes, now spec the brose on their high end MTBs while a number of smaller brands are turning to brose for commuter bikes.

Specialized e-mtb
Specialized have a range of full-suspension and hardtail e-mtbs  (photo supplied)

specialized ebike battery
Battery removed from the Specialized Levo FSR  (photo supplied)

Specialized brose ebike motor
Custom and individual brose motor integration in the Specialized Levo MTBs  (photo supplied)


For German speakers, further information about brose is on their website: brose-ebike.com. If you prefer English, you can use the google website translator tool for fairly good results: brose-ebike.com (translated to English).

For information on BMZ and their battery solutions visit: bmz-gmbh.de (English)

Christopher Jones
Christopher Joneshttps://www.bicycles.net.au
Christopher Jones is a recreational cyclist and runs a design agency, Signale. As the driving force behind Bicycles.net.au he has one of each 'types' of bicycles.
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