The E-Bike Gearbox Has Arrived | Pinion’s MGU Motor.Gearbox.Unit

by | Jun 21, 2023 | Gear, Reviews & First Looks, Bike, E-Bikes, First Look, Sports

German gearbox specialist Pinion has merged the E-Bike motor and the internal gearbox to make an electronically shifting drivetrain with ride support from a full powered electric motor. Here’s what you need to know!

Alright this is exciting. Partly because I have a personal soft spot for gearboxes on bicycles and also because, preferences aside, what Pinion has done with their new Motor.Gearbox.Unit (MGU) is very innovative in the fastest growing division of the sport of mountain biking, E-bike technology.

Pinion Mgu Gearbox
Pinion’s MGU Motor Gearbox Unit merges E-Bike drive power with the gearbox system

The modern derailleur drivetrains are very very good. These systems are more robust than ever and deliver a massive gear range with high levels of efficiency and simple shifting. What are their drawbacks? Being very much externally located drivetrains they are exposed to damage in crashes and other mishaps and require regular maintenance (lubrication of the chain). Derailleur systems also increase wear on the chain as the gears cannot all be in perfect alignment with the chainring and the derailleur itself often requires adjusting to maintain good shifting (less so with electronic options).

Aside from these pitfalls (which could be major or minor, depending on your perspective) that we have all learned to live with, the modern derailleur system does a great job of power transfer to the rear wheel and more often than not doesn’t bother the rider.

So what does a gearbox system bring to the table?

Pros of the gearbox system

Reduced unsprung mass and central weight

Being located around the bottom bracket of the main frame, most of the drivetrain mass (aside from the chain, rear hub and rear sprocket) is situated low and central on the bike which increases stability of the system.

Moreover, this takes weight off of the rear triangle / axle and puts it on a part of the bike supported by the suspension. This makes the rear suspension system lighter and able to react quicker to terrain and generally do a better job!

Better suspension design

Because the chain only runs over one cog, bike designers only have to account for the chain being in one position through the travel range and thus can better tune suspension kinematics (which are typically affected by the chain).

Zerode Mountain Bike With Pinion Gearbox
Zerode is a popular mountain bike manufacturer that uses pinion gearboxes in their bikes. Notice the single sprocket at the rear allowing for better suspension tuning and a straight chain line.

Reduced maintenance

As the whole gearing system is sealed it is protected from the elements and thus doesn’t need constant cleaning and lubrication (especially if you then swap out the chain for a belt drive that doesn’t need lubrication). The gearbox only requires oiling every 10 000 km or so and the process is a 10 minute job.

With one chainring in front and 1 sprocket on the rear hub, you can achieve a straight chainline which greatly reduces wear on the chain (making it almost impossible to snap one) and reduces drag slightly.

Protected drive unit

There is no derailleur hanging off the rear axle that can smash rocks. Pretty simple. Everything is tucked away safe and sound!

Shifting while coasting or stationary

A smaller bonus to the system is the ability to shift gears without pedaling (on the E-Bike version and a normal gearbox system). Shift to an easy starting gear while stationary or shift gears to match your speed on the descent for the next pedal section without the need to turn the cranks. Magical and quite useful.

Cons of the gearbox system

Specific frame design

While you can hang a derailleur off of just about every production bike on the market and chop and change drivetrain manufacturers with ease, because the gearbox houses the bottom bracket of the mainframe, the frame needs to be designed around the gearbox in a sense. Not a deal breaker but certainly a hurdle.

System drag

While the perfect chainline reduces drag slightly, the small gears in the gearbox do create a little more drag than the cogs of a traditional cassette. It is not hugely significant but it is perceptible.


The gearbox system is typically about 1kg heavier than a derailleur system. While this location of this weight has benefits for the bike’s stability, this is enough to end the conversation for most.

Shifting under load

With a cable actuated gearbox, shifting under load is not possible as you cannot generate enough torque with your hands to shift the gears. With electronic shifting, it is possible to change gears under load though not quite as much as the latest drivetrains are capable of.

So what makes the Pinion MGU so delightful?

Well essentially you’re getting all the benefits of a gearbox system but without several of the typical drawbacks as the weight penalty and the (minor) drag of the system isn’t an issue when you have an electric motor powering you forward! Pinion have also solved the shifting under load issue with their electronic Smart.Shift technology that is standard in the E-Bike drives which also allows you to shift multiple gears at once something not possible with most E-Bike drivetrains due to the high torque.

Simplon E Bike With Pinion Mgu Gearbox
Simplon E-Bike with Pinion MGU gearbox

The Smart.Shift system also has some cool features that are similar to the recently launched Shimano Di2 E Drive. The system can automatically shift for you on descents to match your speed so that when you get on the pedals you’re always in the right gear. It also has the capacity to automatically shift to your preferred starting gear if you come to a stop on the trail so that when you set off, you have the ideal gear already engaged. Both of these features can be turned off if the rider would like to do so.

Details on the Pinion MGU

You have 12 (E1.12) or 9 (E1.9) geared models offering a 600% or 568% gear range with different gear steps, the same as with their non-motorised options (P1.12 and P1.9)

The motor output is up to 600W and effectively 85 Nm of torque. Having read some reviews from testers who have been able to ride the new system, the motor is on par with, if not exceeding, the most powerful traditional E-Bike motor options on the market. 

FIT E-Bike systems provide the batteries, display, and controller for the MGU and give one several options on that front. Battery size options are 480, 720, and 960Wh + a 470Wh range extender. Imagine the ride you could do with a 1430Wh battery on your full powered E-Bike!

The E-Bike Gearbox Has Arrived | Pinion'S Mgu Motor.gearbox.unit
FIT Bike’s range of component options to pair with the MGU

You’ll get an app that can connect to the bike and fine tune your preferences for power in the 4 modes (ECO, Flow, Flex, and Fly) and the control unit on the handlebar can trigger a burst of maximum power input if you hold the walk assist button down while riding. That could be fun!

Pinion Mgu Gearbox App
FIT App for MGU

The unit works with either a traditional chain or a Gates Carbon Belt Drive for further reduced maintenance (no lubrication required, just cleaning as with the rest of the bike).

The MGU is not much bigger than the current popular motor options on the market and weighs 700-800g more than the motor + derailleur and cassette. Not a significant penalty on an E-Bike especially given the suspension and maintenance benefits. It appears to have better ground clearance as well.

Pinion Mgu Geabox Info
Pinion MGU info

What we are skeptical about

Honestly, not much. The shifting still is not as smooth as a normal derailleur drivetrain and will feel a bit like a step backwards in performance at first which will be enough to sway many away from the concept.

The system is still heavier than what we are used to but that shouldn’t bother an E-Bike owner too much.

Bikes that will come with an MGU

Simplon, Rotwild, Flyer, Bulls, and a couple of other manufacturers are the first to adopt this technology and will be releasing E-MTBs and commuter bikes with the MGU in the coming months.

Where we think it will make the most sense

This technology is very well suited to commuter bikes. The low maintenance factor alone is a huge win, the stop-start nature of commute riding means that shifting without pedaling and the auto shifting features will be very convenient. Fully automatic shifting with this system might not be too far over the horizon.

Flyer E Bike With Pinion Mgu Gearbox
The added weight will be of less concern on commuter bikes as they simply are not as performance focussed as the E-MTBs.

As for those E-MTBs, I am excited about the potential here. The suspension design and performance benefits will certainly be attractive to more manufacturers and riders and that coupled with the integration of the system and its robustness gives me confidence that we will see the MGU on more and more E-MTBs. Will it be a gateway drug for more manufacturers to get gearboxes onto their acoustic bikes? It might just be so. Here’s hoping anyway!
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