The Bosch Performance CX Race isn't a completely new motor any more. But this is our first encounter with this much-talked-about motor. The CX Race is based on the Bosch Performance CX Gen4 motor, which was launched in 2019. The CX Race too delivers 85 Nm of torque, but it is a couple of hundred grams lighter at 2.75 kg. Watch our video showcasing the motor's performance or read on for more details.
The Smart System is not just an upgrade with Bluetooth support, a GPS module, app, battery, and such. The motor remains the same, but it's software is completely new. The Bosch P-CX has become a very comfortable motor, and it is easily controlled in Turbo mode. I've said repeatedly that the Shimano EP8 provides a great balance between power and control. It is easy to control in maximum assistance. However, the Bosch Performance CX Smart System now performs just as well in Turbo mode.
Do we really need Eco mode on a Race motor? Well, of course we do. This motor can still be used like a regular Performance CX. We think it's a good idea replacing Eco with Turbo. Race mode is quite aggressive, and we enjoyed having access to full power through the Boost mode too, which is easier to control. I would rather dial down Tour+ a bit and use it as an Eco mode. The Emtb mode could also be adjusted down slightly to even out the gaps between assistance modes. This can easily be done through the Bosch Smart System app.
We did most of the testing with Race set to +4 and +5 to experience how strong the motor can be. Yes, the motor kicks in quickly and forcefully in Race mode, but not more forcefully than the old Performance CX Gen2 with the small chainring did. And yes, the motor continues to push even after we stop pedaling. This can be problematic in technical terrain where the motor pushes us into trouble.
Nevertheless, the motor is responsive and easy to control in Race mode. If you pedal gently and make sure the motor doesn't deactivate, it responds immediately and smoothly to changes in pedaling force. It's possible to keep the motor active even with very little force on the pedals. We can ride very slowly and cautiously while maintaining full control. This was a bit surprising to me.
However, it can be an advantage switching to Turbo for the most technically challenging trails. We still have plenty of motor power in difficult climbs, and the motor is comfortable and easy to work with. Of course, we can also step down to Emtb mode. This slightly improves motor control, but it wasn't really ever necessary.
The downside is that sometimes we may want to stop before an obstacle and go around it, but it can be difficult to maneuver if the motor pushes too much. In technical terrain with frequent starts and stops, motor overrun can make riding more challenging. With this Bosch P-CX Race, we could switch between Race and Turbo, thus enjoying the best of both worlds.
The Performance CX Race encourages a higher pedaling frequency. The motor delivers more and more power as the cadence increases. Surpassing 80 rpm, the motor provides a good push, and at 90 rpm, the thrust intensifies. The motors that are strong at low cadences start to lose their edge here; pedaling becomes soggier and heavier. As we increase the frequency, the motor feels stronger and stronger. Yes, the power eventually diminishes with the P-CX Race as well, but we can maintain an unusually high cadence. Bosch claims that the motor is strongest between 60 and 120 rpm.
The only times I experienced a hard cutoff were during acceleration, like on a slight downhill slope. I could feel a sort of clunk when the motor abruptly cut as I blasted past 27 km/h. However, I find this completely unproblematic. When riding consistently at speeds around the motor cutoff, the motor engages and disengages smoothly.
Nevertheless, the sound doesn't become excessively loud, and there is no annoying motor whine at high cadence. The rattling noise is still present; it can be heard when coasting during the descents. I don't know if Bosch has attempted to reduce the rattle on the Smart System motors, as it is still there. However, I have ridden long descents without remembering having heard the noise. Yes, it may be a negative aspect, but it doesn't prevent me from choosing this motor.
The Bosch Performance CX Race was tested on a Mondraker Crafty Carbon.
However, there is a problem. I really like the Race motor. Why should I buy the regular P-CX motor? Well, the Race motor comes in limited numbers. That means it will be expensive and possibly difficult to get a bike with the P-CX Race. Why can't the regular P-CX have a Race level too? Or a "Race Light" level? I'm expecting a software update soon, thank you in advance, Bosch.
Bosch Smart System
I have barely tested bikes with Bosch motors in the past year and a half. This is the second time we have ridden a motor with the Smart System upgrade. We found the motor to perform well when we tested the Unno Mith last autumn, we rode Turbo-mode surprisingly much. But we didn't do a test of the Smart System upgrade, not untill now.|
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The Smart System is not just an upgrade with Bluetooth support, a GPS module, app, battery, and such. The motor remains the same, but it's software is completely new. The Bosch P-CX has become a very comfortable motor, and it is easily controlled in Turbo mode. I've said repeatedly that the Shimano EP8 provides a great balance between power and control. It is easy to control in maximum assistance. However, the Bosch Performance CX Smart System now performs just as well in Turbo mode.
Four Assistance Levels
The Race motor haven't got Turbo mode. It offers the following four levels: Eco, Tour+, Emtb, and Race. However, Bosch decided to change the setup on the motor we tested. It still has four levels, but they are Tour+, Emtb, Turbo, and Race. Eco has been replaced with Turbo. This is not a change that can be made through the app; it must be done by a Bosch dealer.Do we really need Eco mode on a Race motor? Well, of course we do. This motor can still be used like a regular Performance CX. We think it's a good idea replacing Eco with Turbo. Race mode is quite aggressive, and we enjoyed having access to full power through the Boost mode too, which is easier to control. I would rather dial down Tour+ a bit and use it as an Eco mode. The Emtb mode could also be adjusted down slightly to even out the gaps between assistance modes. This can easily be done through the Bosch Smart System app.
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Motor Behavior
I expected Race mode to be a mode specifically designed for racing, something that can be a hand-full to ride. A truly hardcore assistance level. But it's not, Race mode is surprisingly easy to control.We did most of the testing with Race set to +4 and +5 to experience how strong the motor can be. Yes, the motor kicks in quickly and forcefully in Race mode, but not more forcefully than the old Performance CX Gen2 with the small chainring did. And yes, the motor continues to push even after we stop pedaling. This can be problematic in technical terrain where the motor pushes us into trouble.
Nevertheless, the motor is responsive and easy to control in Race mode. If you pedal gently and make sure the motor doesn't deactivate, it responds immediately and smoothly to changes in pedaling force. It's possible to keep the motor active even with very little force on the pedals. We can ride very slowly and cautiously while maintaining full control. This was a bit surprising to me.
However, it can be an advantage switching to Turbo for the most technically challenging trails. We still have plenty of motor power in difficult climbs, and the motor is comfortable and easy to work with. Of course, we can also step down to Emtb mode. This slightly improves motor control, but it wasn't really ever necessary.
Pushing On
The push after we stop pedaling is often referred to as "Motor Overrun." Shimano calls it "Motor carry-over," and Bosch calls it "Extended Boost." Yes, it requires a slightly different cycling technique compared to a motor that cuts immediately. With "overrun," we can stop pedaling for short moments, and the motor continues to push. If we need to keep the cranks horizontal to clear an obstacle, the bike doesn't come to a halt; the motor helps us up and over the obstacle.The downside is that sometimes we may want to stop before an obstacle and go around it, but it can be difficult to maneuver if the motor pushes too much. In technical terrain with frequent starts and stops, motor overrun can make riding more challenging. With this Bosch P-CX Race, we could switch between Race and Turbo, thus enjoying the best of both worlds.
How Powerful is this Motor?
The motor does not feel particularly powerful when cycling slowly with a slightly lower cadence. One doesn't realize the motor's strength until pedaling faster. Other motors can be very powerful even from a standstill, allowing us to climb steep hills without using the lightest gears.The Performance CX Race encourages a higher pedaling frequency. The motor delivers more and more power as the cadence increases. Surpassing 80 rpm, the motor provides a good push, and at 90 rpm, the thrust intensifies. The motors that are strong at low cadences start to lose their edge here; pedaling becomes soggier and heavier. As we increase the frequency, the motor feels stronger and stronger. Yes, the power eventually diminishes with the P-CX Race as well, but we can maintain an unusually high cadence. Bosch claims that the motor is strongest between 60 and 120 rpm.
Motor Cut-off
Bosch says the motor cuts the assistance quite abruptly. The motor delivers maximum power up to over 26 km/h and then it's gone at 27 km/h. The motor doesn't gradually reduce power as the cutoff point approaches; it provides good assistance and tapers off very quickly. In most situations, I don't notice the abrupt drop of motor power. I prefer having high assistance for as long as possible, and I find the power reduction to be fine.The only times I experienced a hard cutoff were during acceleration, like on a slight downhill slope. I could feel a sort of clunk when the motor abruptly cut as I blasted past 27 km/h. However, I find this completely unproblematic. When riding consistently at speeds around the motor cutoff, the motor engages and disengages smoothly.
Noise
The Performance CX Race is not among the quietest motors. However, we don't find the motor noise bothersome. In fact, after the first ride, we couldn't even remember hearing any motor noise. On the second ride, we listened for it, and yes, there is some noise coming from the motor.Nevertheless, the sound doesn't become excessively loud, and there is no annoying motor whine at high cadence. The rattling noise is still present; it can be heard when coasting during the descents. I don't know if Bosch has attempted to reduce the rattle on the Smart System motors, as it is still there. However, I have ridden long descents without remembering having heard the noise. Yes, it may be a negative aspect, but it doesn't prevent me from choosing this motor.
Conclusion
No, Bosch Race is not an unmanageable motor that can only be handled by a skilled rider. The Bosch Performance CX has become a great motor. And the Performance CX Race is similar but with the Race mode as an extra dimension. Surprisingly, I used and preferred the Race mode a lot. It adds an extra layer on top of a regular emtb motor, an assistance mode that really brings out everything the motor has to offer.The Bosch Performance CX Race was tested on a Mondraker Crafty Carbon.
However, there is a problem. I really like the Race motor. Why should I buy the regular P-CX motor? Well, the Race motor comes in limited numbers. That means it will be expensive and possibly difficult to get a bike with the P-CX Race. Why can't the regular P-CX have a Race level too? Or a "Race Light" level? I'm expecting a software update soon, thank you in advance, Bosch.
