Light touch updates should refine performance on the trail
Bosch’s all-new full-power Performance Line CX ebike motor has received a host of updates for 2025, just under 10 years after the model’s initial release.
However, the new motor’s torque, power and assistance levels remain unchanged, sitting at 85Nm, 600w and 340 per cent respectively.
The changes drop 100g from its headline weight figure and are claimed to reduce rattle when freewheeling over rough terrain.
Its pedal, cadence and torque sensors have been updated to provide richer data to the onboard computer. New accelerometers measure movement in six dimensions while also analysing tilt, incline, and vibration data.
Software updates add new features like hill start assist and walk assistance, and two new batteries – 600Wh and 800Wh – are added to the PowerTube lineup.
A new bar-mounted Purion 400 display is also introduced with a more streamlined look.
A hushed approach
While the updates to Bosch’s longstanding Performance Line CX motor seem incremental at best – a hundred grams here, some extra sensors there, and a few more watt-hours all included – there’s a little more at play.
Shimano’s DU EP-800 and subsequent EP-801 motors were criticised for their ‘death rattle’ – the knocking noise made on rough terrain when freewheeling.
While early editions of Bosch’s CX were rattle-free, we’ve found more recent CX motors suffered as badly as Shimano’s from the distracting sound.
It’s great to see a redesign of the motor’s gearbox addresses this issue head-on.
The new design is not only claimed to offer a “balance between power delivery, efficiency and noise,” but it also “decouples” your bike’s drivetrain from the motor.
This decoupler should mean, pedal kickback, chain growth, and micro-inputs caused by the bike’s suspension compression, or the rider rotating the cranks, shouldn’t cause the motor’s freewheel to constantly engage and disengage, reducing on-trail rattle.
Shaving grams
When the Performance Line CX Race motor launched, we were impressed with the 250g weight saving and increased power.
While the newest standard CX motor doesn’t tap into the extra assistance levels of the sportiest version, it drops 100g versus the outgoing model now tipping the scales at 2,800g.
Bosch’s latest motor is now lighter than the Brose unit’s 2,900g weight (used on Specialized bikes and SRAM’s Powertrain), but it’s still heavier than the svelte Shimano EP801’s 2,600g figure.
Bosch says the newest CX has a magnesium casing that’s been painted to protect it from stone chips and corrosion.
More than enough power
Unlike most new products, the Performance Line CX motor doesn’t try to outdo its predecessor in terms of torque, power or assistance.
Sticking with 80Nm, 600w, and 340 per cent assistance, Bosch clearly feels its motor had more than enough oomph.
A lot of people would tend to agree with this sentiment, too.
The Performance Line CX has frequently been crowned king of the hill in terms of assistance feel and sheer torquey wallop.
Moreover, the motor’s mapping has proven to be the special ingredient materialising those on-paper figures into real-life feel – Bosch’s motors respond impeccably to rider input, mirroring how much effort its rider exerts with just as much assistance, no matter the cadence.
The sixth dimension
Hopefully, the improved sensors of the latest version will enhance the motor’s feel.
A range of high-quality, data-rich sensors have been fitted. These detect pedal input information – at more than 1,000 times a second according to Bosch – with cadence and torque data.
Internally, acceleration and rotational speeds are also measured – now in six dimensions.
These detect inclination, tilt, and vibrations, so the motor can discern when it’s ascending, and how steep the incline is, along with whether you’re riding on a smooth road or a rough trail.
A remapped motor control unit translates this data into perfectly tuned assistance levels.
Boosting watt-hours
A new 800Wh battery ups range and ride time over the brand’s previous biggest 750Wh unit.
The new battery boasts an energy density of 205Wh per kilogram – up on the 174Wh per kilogram of the 750Wh model.
A lowered-powered 600Wh has also been released – down 25Wh on the current 625Wh unit.
Crucially, the new batteries have the same external dimensions, so bikes can be upgraded or replaced with either model.
The PowerMore 250Wh external battery is compatible with the newest Performance Line CX motor.
Discrete displays
Also new is the Purion 400 display.
Much like Shimano’s ebike screen, Bosch’s newest model sits on the right hand side of the handle bar next to the stem.
Its 1.6in size has enough space for “essential riding and fitness data,” offering a much smaller and more discrete alternative to the Kiox and Nyon displays currently on offer, but way more information than the System Controller or LED Remote most eMTBs are shipping with these days.
Stopping on a dime
Introduced at the same time as the new CX motor is eBike ABS Pro.
Bosch’s ABS has been in its lineup for a few years now, but was primarily designed with urban and cargo bikes in mind.
The new ABS Pro setup takes things up a level.
Designed explicitly for off-road riding, the ABS Trail Pro is for the general mountain biker and ABS Race is for enduro racers and riders.
According to the brand, this new system aims to balance control with braking power, all without the front wheel locking up.
Hill start assist, similar to your car
Finally, Bosch has programmed in a hill start assist mode to its new motor.
Operating similarly to the hill hold function found in most modern motor vehicles, hill start assist should help stop the bike from rolling backwards down an incline as you set off.
According to Bosch it does this by using its internal sensors to discern how steep the slope is, and provide the perfect amount of support to get you going on your merry way.
Walk assistance now adapts the speed of the bike’s walk feature to how fast you’re walking, rather than the other way around.