Bosch Performance Line CX Race motor first ride review – a new race-specific eMTB motor

Bosch has released a brand new motor, the Performance Line CX Race. The new drive unit isn't replacing the regular Performance Line CX motor but extra support boosts performance and reduced weight is aimed at eMTB racing.

Bosch's goal with the new motor was to specifically cater to eMTB racers. As eMTBing continues to grow in popularity, eMTB racing is beginning to gain proper traction, with both the XC lap World Champs format and e-enduro such as the Enduro World Series (EWS-E). High level racing puts a huge demand on the best eMTB motors so in order to better tailor performance to racing, Bosch focussed on faster acceleration and maintaining top speed.

Does Bosch's new Performance Line CX Race motor unlevel the eMTB race playing field? Well, we were lucky enough to get a first ride of this limited edition race motor at TweedLove mountain bike festival and took it for a ride to try and find out.

Design and specifications

The motor’s torque rating hasn't changed but the big upgrade is in the support levels that are offered. The Race motor now offers 400 percent support compared to the 340 percent of the regular Performance Line CX motor. The torque levels remain unchanged, though, so you are still getting the 85Nm. While we probed, Bosch remained tight-lipped about the maximum wattage output of the motor.

It's not only the support levels that have been upped. Bosch also says the range of cadences the motor supports have also been broadened though again, the manufacturer haven't supplied specifics and simply state that it can still provide support at cadences over 120 rpm.

The new motor uses Bosch eBike Flow smartphone app so riders can tun the levels of support, extended boost, and other behaviours of the motor

The new motor uses the same bolt patterns which will please bike manufacturers and the magnesium casing certainly looks a little more compact. Bosch has worked to drop the weight of the new motor to 2.75kg – arguably that's not going to make a massive difference as part of a bike’s overall weight, but marginal gains are gains nonetheless.

More important than the marginal gains is how it performs against the competition. It's certainly a step up from the existing Bosch motor, though the Shimano EP8 and Yamaha PW-X3 already offer around 400 percent support. Numbers on paper don't always translate to ride experience, however, and I found the CX Race to be considerably more controlled and predictable compared to Shimano's offering. 

They are also already a weighing in around the same weight too, although mounting fixtures of frames can arguably play a larger role in weight of a system than the motor alone. 

Performance

Moving from Turbo mode's 340 percent support to 400 percent support in the Race mode is bluntly noticeable, meaning the motor is putting out four times the power you put in. In the same way Turbo makes Tour+ mode feel dull on the Performance CX motor, the Race mode makes Turbo mode seem almost lackluster. Power is delivered in a very direct manner and the extra support is most noticeable  at mid to high speeds, with a very smooth but urgent delivery. The delivery is better on fringe cadence levels, meaning you are less likely to miscalculate a section of trail and get caught mashing at your gears in the hope the motor will kick back in.

Bosch says that 'only those with precise riding technique can control the direct response and power of the Race mode' but I found the motor to be generally very predictable and respectful of pedal input. It must be noted that trail conditions were particularly dry and grippy during our test ride which certainly helped. Considering there is a decent increase in support, though, I never felt like the bike was desperate to surge uncontrollably from under me or spin the wheel uncontrollably, even on steeper sections of trail. 

While this could be the result of more refined motor sensors or the wider cadence band being more forgiving to riders pedaling input, there might be more than just motor response at play here. Crux or technical sections are often a lot easier to clear at speed and the additional support from the motor is going to make sure you're riding into these sections considerably faster.

The increased Extended Boost gives a heap of over run to overcome technical sections, with what feels like the equivalent of around two extra pedal strokes. That means you can hesitate on the pedals, optimize your body position or lunge the bike before getting back on the pedals without losing traction or momentum. 

While the Extended Boost is a useful tool on the climbs, it needs to be treated with caution. When pedaling into flat or loose corners you need to be mindful of the extra power going to the rear wheel, potentially backing off earlier in order to avoid the rear wheel breaking traction. You also need to be a little more aware of your pedal position on technical sections, as even small pedal inputs can engage the Extended Boost and potentially propel the bike forwards suddenly. It can be tuned via the app, or you can switch to Turbo mode which has far less over run for trails that don't need full race mode.

Early verdict

While the Trek Rail host bike is a pretty good climber already, the motor’s support and Extended Boost meant it was generally well-behaved and diligent, rather than frenetic and panicked, which can be the experience when a motor is being pushed hard and is finding its limit.

Instead, the Bosch Performance Line CX Race feels controlled and focussed, driving the bike forwards in a very direct manner. It's hard to say how much effect this motor will have on the outcome of racing, as I was unable to do any back-to-back testing. However, the 400 percent support, additional Extended Boost, and smooth controlled delivery of power is impressive and certainly going to add a noticeable boost to racers lucky enough to get their hands on one of these limited edition motors.

The bad news, Bosch are saying the motor is only going to be available in limited quantities. Around 20 of the leading manufacturers have been earmarked to receive the motor and we believe each of these brands will only receive limited numbers to fit to their best electric mountain bikes. Its hard to believe that Bosch won't make this motor more readily available in the future, but for now it will be the reserve of the lucky few.

Tech Specs: Bosch Performance Line CX Race motor

• Discipline: eMTB Race
• Torque [Nm]: 85Nm
• Support: 400 percent
• Motor weight (kg): 2.59kg
• Availability: Limited edition and unconfirmed