Today sees the official introduction of the Bosch Performance Line SX motor. Purpose-built for the lightweight e-MTB market, the hotly-anticipated Performance Line SX motor is the German brand’s first foray into this fledgling category that includes popular bikes like the Specialized Levo SL, the Trek Fuel EXe and Orbea Rise.
Ready to take on the likes of the Fazua Ride 60, TQ-HPR50 and Specialized SL 1.2 motors, Bosch has come out swinging. The Performance Line SX motor is said to deliver 55Nm of peak torque and up to 600W of power in a package that’s smaller and lighter than the existing Performance Line CX motor. Along with the new 400Wh battery, we expect this is going to be a very popular drive system for future lightweight e-MTBs.
Lighter & smaller, but not that small
Thanks to the use of a magnesium casing and internal changes, the Bosch Performance Line SX motor is claimed to weigh just 2kg. That’s nearly an 800g weight saving over the existing Performance Line CX drive unit.
To put that figure into context, here’s how the new Performance Line SX motor compares to some of the competition;
- TQ-HPR50 – 1.85kg
- Specialized SL 1.2 – 1.95kg
- Bosch Performance Line SX – 2kg
- Fazua Ride 60 – 2.3kg
- Shimano EP8 – 2.6kg
- Bosch Performance Line CX – 2.79kg
As well as being lighter than its full-powered sibling, the Performance Line SX motor is also slimmer. It features a 160mm Q-factor, which is quite a bit narrower than the 178mm Q-factor on the Performance Line CX drive unit.
These changes result in a reduction of the overall size by around 20%. However, because the motor still sits forward of the crank spindle, the Performance Line SX drive unit isn’t as compact as the tiny TQ-HPR50 motor found on the Fuel EXe and Scott Lumen.
There’s a new 400Wh battery
To go with the new Bosch Performance Line SX motor there’s a smaller 400Wh battery. Weighing in at just 2kg, Bosch claims the new CompactTube400 has the highest energy density of any of its batteries.
Combined with the Performance Line SX motor, you’re looking at a total system weight of 4kg. That’s significantly lighter than the 7.19kg system weight of the Performance Line CX motor and 750Wh battery that you’ll find in the Scott Patron and Trek Rail.
In addition to being lighter, the smaller battery also allows frame downtubes to be made slimmer. This saves further weight and also allows for a sleeker profile, much like the unreleased Norco Fluid VLT shown in the photos here.
Up to 600W of peak power
Said to be designed for ‘sporty riders’, the Bosch Performance Line SX motor delivers 55Nm of peak torque and up to 600W of power. However, you’ll have to be pushing hard at a fairly high cadence in order to access maximum support from the motor. This will help to preserve battery life and encourage riders to put more effort in, which typically suits the style and application of a lightweight e-MTB.
To improve overall efficiency, the Performance Line SX motor features new sealing that’s said to reduce pedal resistance by 50%. And to prevent you from draining the battery too quickly Bosch has removed the Turbo mode altogether. This leaves you with Eco as the lowest assistance level, along with the adaptive Tour+ and eMTB modes. You can still tune the motor’s power output using the eBike Flow app – see our separate Bosch Tuning Tips article for more info.
Flow’s Take
We’ve been eagerly awaiting Bosch’s entry into the lightweight e-MTB category, and it looks like the German brand has developed a compelling option with its new Performance Line SX drive unit and 400Wh CompactTube battery. And given that Bosch is arguably the leader in the full-powered e-MTB market, we expect there’ll be a lot of brands eyeing off the new system.
As to how it performs on the trail? We look forward to swinging a leg over a bike in the near future to put the Bosch Performance Line SX motor to the test.
