CX-R motor highlights:
- Power: 750 Watts
- Torque: 100 Nm
- Assist percentage: 400%
- Battery: 600 Wh or 800 Wh
- Weight: 6 Ibs / 2.7 kg
Performance Line CX-R
Bosch offered a Race version of thier prevoius performance line CX motor, and we’ve been waiting for them to do the same with latest generation of the venerable CX. Thankfully we didn’t have to wait too long (at least for the details anyway – it’s not available quite yet), because Bosch has announced that the new CX-R is on the way.
Design & Features
Building off the performance Line CX motor (covered in more detail in here), Bosch has taken a familiar path with the new CX-R motor. Like the CX, the CX-R uses a powder-coated magnesium housing. Internal differences include a titanium spindle and ceramic bearings, both claimed to reduce weight. The CX-R is claimed to weigh just 6 lbs; for reference, that is about a ¼ pound lighter than the current CX motor. The combination of the corrosion-resistant titanium spindle and ceramic bearings is also said to help maintain smooth operation of the motor.
The CX-R does not disappoint on the power side, with a claimed 100 Nm of torque, 750 watts of power, and up to 400% assist. Class 1 eBikes — and the majority of eMTBs intended for trail use fall into that category — are limited to 750 watts, so Bosch has turned the power all the way up to the maximum.
With the latest CX motor, Bosch emphasized improving sensor technology, and they continued that with the CX-R. They claim the CX-R measures pedal input up to a thousand times a second, and can measure acceleration and rotation speeds in six dimensions, while also recognizing inclination, tilt angles, and vibrations.
The CX-R motor offers the rider four assist modes to choose from: Tour+, eMTB, eMTB+, and Race. The Race mode is exclusive to the CX-R, and basically delivers all the beans all the time. Bosch states it’s for riders who want direct power delivery, maximum support, lag-free acceleration, and full power all the way up to the top speed cut off. Think of it like being able to turn off all the electronic nannies (like traction control) in a modern performance car. Extended Boost, which is a Bosch term for how far the motor continues to provide power after you stop pedalling, is is further extended in Race mode.
Should you prefer less aggressive power delivery, Bosch has introduced a new eMTB+ mode, said to bridge the gap between eMTB mode and Race mode. The eMTB+ mode can deliver the same power output as Race mode, but does so with more software intervention which Bosch calls Dynamic Control — and is claimed to be a type of traction control.
The performance values of the modes can be individually adjusted in the Bosch eBike Flow app. The ability to customize the modes is already an available feature in the app, and while not specifically called out, it sounds like there may be enhanced tuning capability with the new motor and possibly the software update as well (see below), but we’ll have to wait and see on that. Unfortunately, Extended Boost duration will not be adjustable as I hoped it would be.
Expect to start seeing the CX-R motor show up in eMTBs sometime in the Fall of 2025.
CX Software Update
When Bosch released the latest version of the CX motor with upgraded sensors and strengthened gears, but with the same power and torque numbers as the outgoing model, we applauded them for refining the CX motor rather than getting into a power war with their competitors. However, we still speculated that the improvements to the Performance Line CX motor weren’t finished, and the upgraded parts would likely be able to handle more power. Well, that speculation has turned to reality with the release of the new performance software upgrade for the CX drive system.
Interestingly, the new software has the potential to bring the CX motor’s output up to the same numbers as the CX-R motor — 100 Nm of torque, 750 watts of power, and up to 400% assist (current CX output is 85 Nm of torque, 600 watts of power, and up to 340% assist). Those are pretty incredible numbers, and I think its great, but it’s a bit surprising Bosch would take the numbers up to the CX-R level, because I think it kind of takes a little bit of the CX-R’s exclusivity away.
Bosch leaves it up to their OE partners to determine what’s most suitable for each model and spec — with that said, they don’t expect any of them to prevent the end user from applying the performance software upgrade, or to limit the power increase in the upgrade.
The performance software upgrade will add the same new eMTB+ mode that is available with the CX-R motor. Like the CX-R motor, eMTB+ mode offers maximum power output, but with Dynamic Control providing a type of traction control to make power delivery easier to manage. You decide which four assist modes you would like loaded into your eMTB from the available modes in the eBike Flow app (Eco, Tour, Tour+, Auto, Sport, eMTB, eMTB+, and Turbo). If you want to add the new eMTB+ mode, you’ll need to remove one of the other modes you had previously selected.
Kiox 400C Display
Just as newsworthy as the power increase, Bosch is finally offering an integrated top tube display with a screen as an option. Up until now, their only choice for a top tube display was the aging integrated top tube system controller. I’ve mentioned many times how I wish Bosch would abandon their minimalist top tube system controller, which gave the rider very basic information via LED bars, in favor of a full-featured top tube display like the ones offered by Specialized, Rocky Mountain, TQ, and DJI. Well, they haven’t abandoned it yet since it will remain in their catalog, but the new Kiox 400C is a big step in the right direction, and my guess is that a lot of brands will choose the Kiox 400C for the types of bikes that will be spec’d with the Performance Line CX, and CX-R drive systems.
The new display features a high-resolution color screen and provides data such as power, battery percentage, cadence, speed, elevation, heart rate, and more. Uniquely, you can opt to have the display data change automatically depending on the riding situation. For example, when riding uphill, it displays elevation accrued, and then when descending, it changes to speed. The idea is that the rider can focus on the trail by keeping both hands on the bars. The various screens are customisable in the eBike Flow app. It also has a USB-C port for charging your phone or other accessories from the main battery.
Other features included in the software upgrade are refinements to eBike ABS and eBike ABS Pro, as well as an M+ update to eShift. M+ automatically shifts to the right gear while coasting, and ensures the rider is in an appropriate gear to put down power without delay when transitioning from descending. eShift is compatible with the TRP E.A.S.I. A12 electronic drivetrain.
The performance software upgrade is expected to be available via an over-the-air update in July.
Some Questions / Things We’re Curious About
(1) On paper, the CX-R motor and the Specialized S-Works 3.1 motor have similar power numbers. How will they compare out on the trail?
(2) The CX motor with the performance software upgrade can have the same power as the CX-R motor, but will they feel the same on the trail, or will the CX-R’s improved sensors and ceramic bearings offer a tangible difference?
(3) The new Kiox 400C display looks to be a substantial upgrade, but how will it compare to the best on the market from Specialized, Rocky Mountain, TQ, and DJI?
(4) eMTB+ mode is an interesting addition, but will it water down the performance too much compared to Race mode?
(5) Who will be the first to implement the new CX-R motor?
Bottom Line (For Now)
The CX-R motor is an exciting addition to one of our favorite eMTB drive systems, and the performance software upgrade has the potential to elevate the current CX motor to an even higher standard. Bosch appears to be on a bit of a roll, and these new developments look to put the pressure on the competition. We’ll report back as soon as we update one of our eMTBs with the CX motor, and look forward to spending time on the new CX-R motor this fall, so be sure to check back in.