Weighing in at a reported 4kg for the full system, the new Bosch Performance Line SX drive unit is aimed at performance-focussed eMTB and eGravel riders. 


Bosch joins the half-fat eMTB motor brigade with the new Performance Line SX; new motor, new battery, new displays and controls, and new features on the eBike Flow App to control it all.

Need to know:

  • Reported 4kg full system weight
  • 600 watt peak power
  • 55Nm max torque
  • Compact 400 Watt battery, plus PowerMore 250 range extender

The new system is aimed at eMTB riders who are looking for a natural ride feel and light support, and Bosch says the system is also ideal for eGravel riders.

New Bosch Performance Line SX eMTB motor

Drive Unit

Thanks to design developments and a magnesium casing, the drive unit weighs in at an impressive reported weight of 2kg. It offers 55Nm of maximum torque and a peak power output of 600 Watts, which is accessible at high cadences. So for example if you’re furiously spinning the pedals and putting in some force up a technical climb, you can access the full available power.

This combination of power plus low weight gives the Performance Line SX a power-to-weight ratio of 300 Watts per Kilogram.


Also new is the battery, the CompactTube 400. This has been specifically adapted to suit the Performance Line SX, works integrated into the downtube and is the lightest battery Bosch produces at a reported 2kg.

It has a 400Wh capacity, which doesn’t sound like a whole lot, so we’ll be interested to see how far that gets you on the trail.

If the answer is ‘not far enough’ then you can bung on the aptly named PowerMore 250 range extender. This water-bottle-sized piggyback battery offers an additional 250Wh on top of the CompactTube 400 and increases the range by around 60% according to Bosch. It also weighs 1.6kg.

New Bosch Performance Line SX eMTB motor

eMTB (and eGravel) ready

Gravel-haters look away now, because a lot of the features that make the Performance Line SX great for fast and light eMTB riding also make it pretty damn good for eGravel riding, and Bosch are certainly pushing this application.

That includes a reduction in pedal resistance by around 50% reported, compared to other Bosch systems, so it gives a more natural feel when the cadence is high. There’s also a new Sprint Mode which detects when the rider is putting in the effort – high cadence, high power – and adds the support more quickly to help the rider reach top speed faster.

Other interesting elements include a lower-noise motor, for stealthier riding, and narrower cranks with a Q-factor of 160mm, again giving a more natural ride-feel.


The new Bosch Performance Line SX will be available retail from Autumn 2023, so if you’ve got your eyes on it, you’ve got time to save up some pennies.