Brose Drive S Mag

Summary

The Brose Drive S Mag is a lightweight, high-torque mid-drive e-bike motor built for aggressive trail and enduro riding. With a 90 Nm output, magnesium casing, and an internal carbon belt drive, it blends powerful assistance with an exceptionally smooth and quiet ride feel. It’s the flagship drive unit in Brose’s e-MTB lineup and a core platform behind bikes like the Specialized Turbo Levo.

Key Facts

  • Introduced: 2018
  • Category: E-Bike System
  • Motor type: Mid-drive, brushless, internal belt-driven
  • Torque output: Up to 90 Nm
  • Maximum cadence support: 130 rpm+
  • Weight: ~2.9 kg
  • Drive casing: Magnesium
  • Chainline: Typically 53–56.5 mm, depending on OEM config
  • Assist levels: OEM-configurable (commonly Eco, Trail, Boost/Turbo)
  • Used by: Specialized, Rotwild, Bulls, M1 Sporttechnik
  • Official website: https://www.brose-ebike.com

Overview

The Brose Drive S Mag represents Brose’s most refined and powerful motor for off-road e-biking. Designed to meet the demands of modern trail, all-mountain, and enduro riders, it pairs high peak torque with a ride feel that prioritizes natural pedal dynamics over abrupt surges. Its magnesium shell helps reduce overall weight, and its internal carbon-reinforced belt makes it nearly silent under load — a standout feature in an increasingly crowded e-MTB motor space.

Launched in 2018, the Drive S Mag was the first Brose motor to use a fully redesigned housing optimized for weight and heat management. Where earlier Brose motors were based on aluminum housings and commuter-friendly specs, the S Mag marked a shift toward purpose-built e-MTB performance.

It’s also notable for its modular approach. Brose doesn’t force a proprietary ecosystem of displays or batteries — instead, the motor is licensed to bike brands who tailor firmware, interfaces, and battery integration to suit their ride philosophy. That makes the Drive S Mag one of the most flexible high-performance motors on the market.

How It Works

Internal Architecture

At the heart of the Drive S Mag is a brushless permanent magnet motor paired with a carbon-reinforced belt drive. Instead of using metal gears to reduce speed and multiply torque, Brose’s belt system reduces friction, eliminates gear whine, and allows for smoother transitions when engaging and disengaging motor support.

The motor is housed in a magnesium casing, which is 500 grams lighter than previous Brose aluminum housings and provides improved thermal efficiency. This allows the motor to sustain higher torque loads during extended climbs without thermal shutdown.

Sensor System

Like all modern mid-drive units, the Drive S Mag uses a triple-sensor setup:

  • Torque sensor: Measures rider pedal pressure
  • Cadence sensor: Detects pedal rotation
  • Speed sensor: Typically integrated at the rear wheel

This setup allows the motor to finely modulate assistance based on real-time rider input. The cadence range is exceptionally broad, supporting up to 130+ rpm. This makes it one of the more adaptable motors for riders who spin fast on climbs or accelerate aggressively out of corners.

Motor Assistance

While OEMs can customize support levels, the Drive S Mag typically supports:

  • Eco mode: Low assistance, high range
  • Trail/Flow mode: Balanced support tuned to cadence and torque
  • Boost/Turbo mode: Full 90 Nm available, sharp power ramp-up

Specialized, for example, has used Brose motors in its Turbo Control Systems, which allow riders to tune power curves, peak torque, and acceleration responsiveness via smartphone apps like Mission Control.

Drivetrain Integration

The motor is compatible with most modern 1x drivetrains, including:

  • SRAM Eagle
  • Shimano 12-speed
  • e*thirteen and Praxis cranks (Super Boost options available)

Chainline spacing varies slightly based on frame design but typically sits between 53 mm and 56.5 mm, allowing for wide tire clearance and compatibility with Boost and Super Boost rear ends.

Ride Feel

Quiet and Smooth

Riders consistently highlight the near-silent operation of the Drive S Mag. The internal belt and low-friction design eliminate the mechanical whine common in most gear-based systems (like Bosch or Shimano). This not only adds to ride immersion but makes the motor nearly invisible on group rides or tight trails.

Responsive and Predictable

The motor engages early and ramps power smoothly, avoiding the on-off feel that can happen with motors tuned too aggressively. Its torque curve is linear, making technical climbs feel manageable without sudden jolts.

Because the motor doesn’t rely on proprietary displays or user interfaces, brands can fine-tune responsiveness to match specific frame designs and rider expectations. Specialized, for instance, offers automatic rider power calibration, while Bulls and Rotwild opt for configurable bar-mounted displays.

Power Under Load

Despite its light weight, the S Mag holds its own under sustained power demands. The magnesium casing helps it shed heat faster, making it one of the few lightweight motors that can deliver full torque on long climbs without throttling back due to thermal limits.

Notable Implementations

  • Specialized Turbo Levo (Gen 2 & Gen 3) – Custom Brose Drive S Mag motor branded as “2.1” and later “2.2”, integrated with Turbo Control Unit
  • Bulls E-Core EVO EN – 150 mm enduro bike using full S Mag drive for aggressive descending
  • Rotwild R.X750 – All-mountain e-MTB featuring Brose power + integrated 750 Wh battery
  • M1 Spitzing Evolution S – High-speed pedelec version tuned for 45 km/h performance

Related Terms

References

  • Brose Drive S Mag Technical Manual
  • Specialized Turbo System White Paper
  • Gates Carbon Drive System Overview
  • Pinkbike: “First Ride – Bulls E-Core with Brose Drive S Mag”
  • EMTB Forums: Owner feedback and long-term ride reviews
  • Bulls & Rotwild Product Integration Guides
  • Dealer Tech Training (Brose / Bulls / Specialized)
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