Bosch explained: Drive unit specs, torque and assistance

Bosch have been making electric motors for a really long time, so it's no surprise that they're a dominant player in the e-bike market. They've released a new range of motors recently, and the names make it all a bit confusing, so here's an explainer to help you figure out exactly what motor you're looking at.

Bosch System 2

Bosch's System 2 motors used a 3-bolt frame interface. For many years they set the standard for e-bike systems, and there are still many bikes using them today.

Motor	Peak torque
Active Line	40Nm
Active Line Plus	50Nm
Performance Line	65Nm
Performance Line CX / Cargo	85Nm

You'll find Bosch System 2 drive units on bikes like the Tern Quick Haul, and Tern Quick Haul Long.

Bosch Smart System with Gen4 drive units

The Bosch Smart System introduced new connectivity, and while initially it used the same motor format, it boosted the peak torque of the Performance Line motors from 65Nm to 75Nm (other drive units stayed at the same peak torque).

You'll find Smart System Gen4 Performance Line drive unit on the Riese & Muller Carrie, the Gen4 Performance Line CX is on the Riese & Muller Nevo4, and the Gen4 Cargo Line drive units are on the Tern GSD Gen3 S10, Tern GSD Gen3 P00, and Tern GSD Gen3 R14.

Bosch Smart System with Gen5 drive units

The latest generation of Bosch motors use a 2-bolt frame interface, and are generally smaller and lighter (the Hub Line is a new hub motor system, a first for Bosch).

Motor	Peak torque
Hub Line	45Nm
Performance Line SX	55 -> 60Nm
Performance Line	75Nm
Performance Line PX	85 -> 90Nm
Performance Line CX / Cargo	85 -> 100Nm -> 120Nm

Why is a range of torque values given for some of these drive units? Bosch has released two sets of Performance Upgrades for these bikes - these are purely software updates, performed by the rider through the Bosch Flow app.

The first Performance Upgrade took:

Performance Line SX from 55 to 60Nm
Performance Line PX from 85 to 90Nm, and
Performance Line CX / Cargo from 85 to 100Nm.

Performance Upgrade 2.0 was then released, which took Performance Line CX / Cargo all the way up to 120Nm (but not for bikes with Enviolo hubs, since this is too much torque for those hubs).

You'll find the Performance Line SX motor on the Kalkhoff Image L-series.

The Performance Line motor is found on the Kalkhoff Endeavour 3 Move, and the Kalkhoff Image C and Endeavour C.

The Performance Line PX motor is on the Nevo5 in the "CORE" range.

Many bikes in the R&M range use the Performance Line CX motor (Nevo5, Homage5, Delite5, Superdelite5, and Charger5).

The Cargo Line is found on the Multitinker2, Load5 60, and Load5 75.

How much torque do I need?

This is a tricky question - it depends on your bike, its gearing, how strong your legs are, the hills you're riding, and what cargo you're carrying.

Here at Omafiets, we have some nearby steep hills in Sydney Park that are the perfect terrain for testing out the different motors, so you can see for yourself which is the right e-bike.