First Look | Bosch Performance Line CX Gen 5 software updates alongside all-new CX-R motor and Kiox 400C Display

The internet rumour-mill has turned out to be true about a Bosch software update, and the battle for the highest performing eMTB drive-unit is hotter than a Carolina Reaper chilli.

Bosch has unveiled it’s all-new Performance Line CX-R drive unit, replacing the outgoing Performance Line CX-Race unit. Alongside the new motor is an all-new Kiox 400c display, and a software upgrade to boost power to the existing Gen 5 Performance Line CX drive units, so there’s a heap to cover here!

Bosch Performance Line CX Gen 5 Software Update

The Gen 5 iteration of the popular Performance Line CX motor debuted in September 2024, however it had identical power and torque numbers to the Gen 4 motor at the time of launch. The 85Nm of torque and 600W of peak power were nothing to be laughed at, but didn’t quite rival those elsewhere in the market based on numbers alone.

It turns out the Germans have been developing a software update for the Gen 5 units. Set to roll out in July, the update will raise peak torque to 100Nm and peak power to 750W. It will also increase maximum support from 340% to 400%, helping riders reach speed more quickly and with less effort.

Software updates will be configured free of charge via the brand’s Flow app, where users will be able to further refine drive unit characteristics in each mode. It’s worth noting that this software update will be subject to the bike manufacturer’s approval for each given bike. It will also only be compatible with the Gen 5 motor, and the software won’t work on older units.

Alongside the performance spec upgrades is an all-new eMTB+ mode. Set to bridge the gap between the existing Race and eMTB modes, eMTB+ is claimed to offer greater dynamics and control. This utilises the maximum support value of 400% and is said to improve the unit’s response to variable conditions, delivering balanced and smooth power.

We’ve spent a fair bit of time on the Gen 5 motor already, being fitted to the Santa Cruz Vala we recently reviewed. It’s an impressive unit, but the biggest takeaway is that the clacking noise that plagued previous Gen 4 drive units has been radically reduced. It’s not totally silent, but a significant improvement. The boosted power and torque will only improve upon the already epic drive unit, making it that little bit more punchy up the climbs.

With all that tech now in our brains, let’s have a quick look at how these updates stack up against the current competition.

• Specialized 3.1 | 101Nm, 666W, 2.9kg
• Specialized 3.1 S-Works | 111Nm, 720W, 2.9kg
• DJI Avinox M1 | 120Nm, 1000W, 2.58kg
• Shimano EP801 | 85Nm, 600W, 2.7kg
• Bosch Performance Line CX Gen 5 | 100Nm, 750W, 2.8kg
• Bosch Performance Line CX-R | 100Nm, 750W, 2.72kg

Bosch Performance Line CX-R

Replacing the outgoing Performance Line CX Race drive unit, the all-new CX-R is claimed to be the highest-performing motor the brand has ever produced. It features higher resolution sensors, a titanium crank spindle, and ceramic bearings, housed within a lightweight magnesium casing. The claimed weight of the CX-R is 2.72kg, almost a 100g saving over the standard CX model.

Peak torque caps out at a whopping 100Nm, up from 85Nm, bringing it in line with the big hitters currently on the market. Peak power is set at 750W, a huge jump from 600W, but doesn’t quite match the insanely powerful 1000W DJI Avinox M1. As usual, motor settings will be configurable in the Bosch Flow app, allowing riders to tailor the output to their preferences.

Exclusive to the CX-R is the ‘Race’ mode, which won’t be found on the CX drive unit. Race mode enables lag-free acceleration and assist with full power up to maximum speed, with up to 400% maximum support. It also features ‘Extended Boost’, essentially the motor overrun, extended further in Race mode compared to other modes.

The upgraded sensors include a precise torque measurement and a “high-resolution” cadence sensor, measuring pedal input up to a thousand times per second. Bosch claim the integrated inertia sensors measure acceleration and rotation speeds in six dimensions, picking up inclines, tilt angles and vibrations. These are fed back into the control system to vary the motor output.

Bosch Koix 400C Display

When the Performance Line CX Gen 5 launched in September 2024, the newer Purion 400 display was unveiled alongside it. This was a handlebar-mounted display, with a similar look and feel to Shimano’s EM800 unit. The Purion 400 struck a middle ground between the minimalistic top-tube System Controller and data-rich Kiox 300. Although the Purion 400 provides access to a wealth of data, the preference for a lot of riders is a minimalistic cockpit, with the trend going towards integrated top tube displays.

Bikes sporting the Performance Line CX Gen 5 motor were being released with the basic top-tube System Controller surrounded by a larger blanking plate, which left us wondering when a larger top-tube display was coming.

Turns out it was just around the corner, and Bosch has broken cover of the new Kiox 400C. Integrating neatly into the top tube, the Kiox 400C features customizable display settings and automatic brightness adjustment. There are tactile buttons to control the display, or a bar-mounted ‘Mini Remote’ allowing you to keep your hands where they should be while riding.

There is even a dynamic screen mode, which displays relevant information depending on the riding situation. For example, it will show elevation when you’re climbing, and speed going downhill. There’s even a USB-C port for that quick charge of a smartphone or GoPro!

Can you buy the Kiox 400C separately, you may ask? According to Bosch, the Kiox 400C will be available to purchase separately, although pricing and availability isn’t yet confirmed. It will however be available on compatible bikes from July onwards.

We’ll be updating our test bikes as soon as the software update becomes available in July. Stay tuned for our ride impressions following the software upgrade, with the boost in torque, power, and the all-new eMTB+ mode!