More power but with limits in mind

Bosch just launched the Performance Line CX Race Limited Edition e-bike motor, specifically e-MTBs. Bosch equipped e-bikes have, over the last five years, developed into some seriously competitive trail weapons that are on par with high-end enduro bikes. From the standpoint of agility and weight, the motors, though, have maintained a more pedestrian pace of development. There has been a move into lightweight systems, for example. It’s now possible to buy an urban bike or an e-MTB; both will have the same motor and, in some cases, very similar software. Well, Bosch has been thinking hard on this and have responded with a race-tuned e-MTB motor where everything changes.

The key points are not immediately obvious or appear to be much different on paper than the non-Race model. Close inspection, though, and discussion with the product managers on hand to answer our questions showed us what has changed. The weight has been reduced by around 150 grams (0.33 pounds). This was achieved by changing the gear materials inside the motor. The layout or ratios are apparently the same, and the motor cases remain the same, albeit with the change to gray. This different material used has made the motors we tested quieter on descents but does not make any difference to the longevity of the system.

Video: The Bosch Race Motor

The power and torque remain the same within all road-legal limits. However, the powerband and torque band—including responsiveness of the motor, meaning reaction time to pedal input—have all been drastically altered. When in Race mode, now the motor responds like a highly reactive race car engine. Immediate power with a fast ramp-up, plus direct control of the motor’s special extended function called “extended boost.” This means if the rider holds pressure in pulses on the pedals without completing a full rotation, the motor maintains its power at a much higher level, spinning the chain wheel for slightly longer, meaning the bike keeps moving over an obstacle if used at the right moment. This can only be felt on the bike when moving and is not visible on paper. This function is actually Bosch taking advantage of a technical facet of the motor, which they normally felt needed to be tempered; now they are using it to full effect to help riders on the trails.

“This function is actually Bosch taking advantage of a technical facet of the motor, which they normally felt needed to be tempered; now they are using it to full effect to help riders on the trails.”

On a technical trail the rider now has a very dynamic power response that they can use to lift the bike over difficult trail obstacles much easier. This motor reactivity saves time, and thus when racing could make the difference on the leader board. Particularly when exiting corners or changing speed repeatedly, the bike will now lead the rider. Noise levels during pedaling are the same as the old motor, as is heat management and interface points. We did notice
on descents there is less gearbox rattle.


Compared to all the motors we have tested, we can say the race motor was a completely different animal compared to the standard Performance CX. We could climb technical trails more easily and boost over small rock outcroppings after a short press on the pedals and correct body-weight positioning. However, at times the motor almost got away from us and needed to be reined in. Obviously, that was why Bosch warned not to use Race mode all the time!

With the Race motor, previously difficult trails to ride with bigger rocks became smoother and more doable. This extra motor control that is now possible will change the way people ride and how they attack trails. In short, it’s definitively a game-changer.

The modes.

To try and illustrate how the Bosch Race motor responds, here is an actual trail scenario that played out for us. 

—Approach the difficult section, standing up on the pedals with weight evenly balanced. You don’t need to ride hard in.

—Choose a low gear.

—At the last moment, just before where you can’t pedal, hit the pedals harder without doing a full rotation. The motor should spin up, driving the bike forward.

—Follow the bike as it hits the rocky outcrop and maintain balance. The bike should pop up and over, and maintain the approach speed on
the exit.

If you did this process above with a normal bike motor, the bike would not respond and likely stop dead. Although there is extended boost on the e-MTB mode, it’s not as powerful as in Race mode and it is shorter in duration. The advantage is clear when spinning the cranks, if the rider didn’t stop making a complete rotation, it would cause them to hit the ground or rocks with the crankarms, so the positive outcome is less pedal strikes using the above method. We stalled the bike less and, in some cases, just hung on as the bike floated over stuff. For new riders, it’s worth taking some time to learn the process and refine it in a play area before racing or even riding the bike hard.

When pedaling normally in Race mode on ascents, you can feel the bike surge forward quickly as acceleration is on the controllable limit if you are not used to it. Even with our level of handling skills, the motor’s power was unnecessary at times, so it’s advisable to switch back to e-MTB mode. We found that we only needed Race mode about 20 percent of the time, even on the steep climbs of Finale Ligure, Italy, where we test rode the motor.  

The motor is the same size but a different weight and color.

The increased reactivity of the CX Race motor also becomes clearer in corners. As the bike powers out of the corner more quickly, there is no delay on the exit. “Think fast, react fast” is the motto, whatever you are doing. We did not notice any vast increase in battery consumption compared to our normal experience with a 750Wh Bosch Smart System battery. However, it needs to be assessed on our home trails, as our perception can be altered according to where we are riding.

Fine-tuning the motor.


Curiously, Bosch is adamant that this is not a motor for everyone. It’s a competition-bred motor that should be available on performance-oriented bikes and for performance-oriented riders. This means it is likely to be on only higher-spec’d bikes in limited numbers. It will not be available as a product to buy then install on your own bike. Bosch was clear it is a commercial experiment that will continue if the demand is high enough. Electric mountain bike racing has some way to go to be widely accepted, but Bosch has proven that they are ready for the demands requested by racers.


If you happen to be one of many e-bike consumers we hear from who wonder if they should buy a bike with the Performance CX Race Limited Edition motor, our answer would be a definite yes if you are going to race e-bikes. If not, but you want to jazz up your ride and you have the riding skills necessary to react to this new motor’s quirks and rapidness, then go for it. Order a bike as soon as you can; they are limited in number. Not all Bosch-mounted bike brands will be producing an e-bike with this system. ν


2.75 kg (6.06 lb.)

Power: 250W

85 N/m

Race, Turbo, e-MTB
and Tour

Limited numbers

Only available on complete bikes, no aftermarket/spares sales