We tested the new software for the Bosch Performance Line CX motor on a Trek Rail 9

Bosch has just announced a software update to its Performance Line CX motor that unlocks more torque and an improved rider experience – and we’ve ridden it.

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No new or additional hardware is required – the motor simply needs to be plugged into a laptop and new software installed – and best of all, it works with all Gen 4 Bosch motors, so if you’ve already got a Bosch-equipped e-bike, you too can enjoy the new upgrade.

Bosch Performance Line CX need to know

• Available as a free software update (no changes to the hardware)
• Works on all gen 4 Bosch Performance Line CX motors
• Raises torque from 75Nm to 85Nm
• Improves power band in EMTB and Turbo modes over a wider range of cadence
• Faster response time for hill starts
• Additional overrun helps you power over obstacles with level pedals

The most eye-catching aspect of the update is the increase in torque from 75Nm to 85Nm. This refers to the rotational force the motor produces, and is particularly noticeable when accelerating from a standstill or slow speeds, and climbing steep hills. It’s often what makes a motor feel powerful through the seat of your chamois. How has Bosch managed to make the motor more powerful with a software update? Well, the obvious answer is that Bosch designed it to have 85Nm of torque from the outset, but de-tuned it for release to ensure that it proved reliable enough. Now that a year has passed, it is obviously confident enough to release the motor’s full potential.

Bosch Gen 4 motor includes a set-and-forget E-MTB power mode option

While the torque boost is the headline act, Bosch has focussed on a making the motor more responsive and effective for aggressive mountain biking, and this it where you’ll notice the biggest improvement on the trail. By manipulating the power and torque curves and using the various sensors, Bosch has sharpened up the response of the motor and improved the power delivery so you can enjoy more assistance across a wider cadence range. Both are really significant improvements for tackling steep or technical climbs, and making successful hill starts should you have to dab a foot part way up an ascent.

Finally, Bosch has worked on extending the thrust provided by the motor when you stop pedalling to get over a fallen log or a step or ledge on a climb. This overrun briefly powers the bike while your pedals are level, so the bike doesn’t grind to a halt and stall your progress. These refinements apply to both the intelligent eMTB mode and Turbo mode.

Best of all, the software update is free. You will need to take your bike into a Bosch dealer to get it installed when it becomes available later this summer (no exact date has been set yet), and some dealers may charge a nominal fee for their time to do this. While there is no official price for this, it shouldn’t be more than £20.

Bosch’s new software seamlessly integrates with the trail to elevate your e-xperience

How does it ride?

Let’s face it, the Bosch Performance Line CX was already a really impressive motor, with plenty of power and an excellent, natural response. But the new software takes its performance to a new level. The additional torque is immediately noticeable at low speeds, and it feels consistently strong whatever cadence you happen to be turning the cranks at. You can keep a steady, deliberate pace up technical climbs to focus on your line without getting bogged down, unlocking trails that were previously out of reach.

The response from the motor is virtually instantaneous too, certainly fast enough that you don’t notice any lag when starting up or resuming pedalling. Hill starts are now much easier because the response time is backed up by more torque at lower revs.

Most impressive though, is the drive you get from the motor when approaching the last phase of trying to clear an obstacle. Whether that’s a log across the trail, or a step on a steep climb, you can give a quick burst of power through the cranks, set your pedals level and pop the bike over the obstacle while the motor continues to drive forward for a split-second. These little kicks smooth out the flow on tricky climbs and put a big grin on your face.

Any e-bike equipped with the latest Bosch Performance Line CX motor can be updated

Does this extra power on tap reduce the range? It’s hard to say how much this update will impact on battery life, but on our test rides, the system still displayed an impressive range. In muddy, slippery conditions, we drained a full battery in eMTB mode over 31.5km with 1,335m of climbing.

To sum up then, in a development that may become increasingly normal as e-bikes become more prevalent, clever programming brings significant improvements to your e-bike’s performance on the trail. No need to bolt on any new components or upgrade internal parts; just plug and play. And the result is that Bosch’s impressive Performance Line CX system just got a whole lot better.