Bosch know how to build things. As far as numbers are concerned, outside of the world of power tools and kitchen appliances they are one of the world’s largest suppliers of automotive parts. The reason I say this is to demonstrate that Bosch have been involved in transport for some time. While they may seem like an odd match at first, when the idea of E-bikes came knocking at the door, Bosch answered.
Since then Bosch have gone all-in on e-bikes. With four models of motor, they’re aiming to have something for everything and everyone.
Of most interest to mountain bikers is the Performance CX. The golden child of the line-up, it’s built from the ground up to work best with mountain bikes both ergonomically and functionally. Take the chassis for example. The latest iteration has a smaller rear to work better with pivot placement on full suspension options negating the need for longer chain stays that e-mountain bikes have historically had to adopt.
It’s also one of the most powerful motors currently on the market, producing 75nm of torque at peak output. More importantly, (and unlike some of the competition) it’s capable of sustaining that indefinitely instead of peaking and troughing in output; as long as the battery has charge the motor will keep turning at full power.
Batteries are currently available in 400 and 500-watt-hour configurations, with the most recent edition being a 500-watt-hour option that can be fully integrated into a frame, so it almost appears as if the bike doesn’t have a battery. Very slick. There’s talk of an even bigger battery on the horizon but nothing official yet. Also new to the range is an adaptive “E-MTB” mode for a natural feeling riding. Bosch want to be at the top of the E-bike market, and the latest offerings are their commitment to that goal.
I was fortunate enough to be amongst the first to meet the new range at Crankworx Rotorua. We were each given a bike, a fully charged battery, and a big bloody hill to find out exactly what the new motor system is capable of.
The Bosch motor system is adjustable to varying degrees of output depending on the riding situation. From a “no assistance” mode that pedals like a regular bike to “turbo” mode that will let you sit at full power for as long as you keep pedalling (or in my case pop wheelies while pointing at the gondola and laughing). I was most interested in the new “E-MTB” mode which feeds back power output dependent on your torque and cadence when pedalling to keep the motor responding as naturally as possible. Note that regardless of mode, the motor always cuts out at 25kph. Want to go faster? It’s all acoustic from there if you do.
I spent most of my time on E-MTB mode. Apparently, Bosch’s pro riders were heavily involved in the tuning of this mode to make it feel as sporty and responsive as possible, so no holds were barred when it came to seeing if this setting lived up to expectations. Of course, the best test of motor responsiveness is to pop wheelies everywhere, so no points for guessing what we all ended up doing... The motor kicks in almost instantaneously with the amount of torque proportional to how hard and fast you work the pedals. Note that I say “almost” as it’s still possible to catch it out if you go from nothing to full gas on the pedals; stompy riders be warned. But that’s a rare occurrence. So long as you’re being nice to the motor, it’s all very natural feeling.
What I appreciate about this motor is not just application of power, but how it goes about cutting out power when the speed limit is reached. Some motors I have tried will spin you up to 25kph quite happily, but the moment that limit is reached they rip the support from under you straight into manual power, a feeling not dissimilar to suddenly shifting up a few gears unexpectedly. The Performance CX tapers you off nicely in a manner that’s much less jarring and much more organic in nature.
In all, I’m pleased with what Bosch has done with the newest iteration of the Performance CX motor. It’s got some slick new tricks tucked into it to work with the next generation of E-mtb’s and lives up to the promises. I look forward to putting some more mileage in on this motor system to see what it’s truly capable of!
Words: Robin Page
Find the complete review of the Cube Stereo and its Bosch engine in Issue 89. Subscribe to our print edition for the best of New Zealand Mountain Biking.