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For over fifteen years, Bosch eBike Systems has been one of the strongest supporters of mid-drive electric bike architecture. Its systems have been widely used on mountain bikes, cargo bikes, trekking bikes, and urban e-bikes.
However, Bosch has made a major strategic shift by introducing the Hub Line (BDU306Y)—its first rear hub motor. Designed for the 2027 model year, the new system targets sleek, minimalist, and lightweight urban commuter e-bikes.
Why Bosch Is Introducing a Hub Motor
Mid-drive motors remain well suited to steep climbs, heavy loads, and demanding riding because they transfer power through the bicycle's drivetrain. However, they also have disadvantages for lightweight urban e-bikes.
- Design: Large bottom-bracket motor housings can make an e-bike look noticeably different from a traditional bicycle.
- Weight: Mid-drive systems combined with larger batteries can make commuter e-bikes relatively heavy.
- Drivetrain Wear: Motor and rider power both pass through the chain and sprockets, increasing wear and maintenance requirements.
The Hub Line gives Bosch another option for riders who prioritize low weight, clean design, and natural urban riding characteristics.
Bosch Hub Line Specifications
| Specification | Bosch Hub Line |
|---|---|
| Rated Continuous Power | 250 W |
| Peak Power | Up to 400 W |
| Maximum Torque | 45 Nm |
| Motor Weight | 2.3 kg (5.07 lbs) |
| Housing Diameter | 100 mm (3.94 inches) |
| Assist Top Speed | 25 km/h EU / 32 km/h North America |
| North America Feature | Optional throttle support |
The compact 100 mm housing helps the motor remain visually discreet behind the rear brake rotor and cassette. Its 2.3 kg weight also makes it suitable for lightweight urban e-bike designs.
Zero-Drag Decoupling
When the bike exceeds the legal motor-assistance speed, the internal clutch disengages. This allows riders to continue pedaling without additional motor resistance.
Easier Hub Motor Servicing
Traditional hub motors can be difficult to service because accessing the motor may require removing spokes. Bosch addresses this with a modular design that allows the internal drive core to be removed from the hub shell.
A quick-disconnect cable along the chainstay also makes rear-wheel removal easier when repairing a flat tire.
Integration With the Bosch Smart System
The Hub Line is not a standalone motor. It is integrated into Bosch's existing Smart System ecosystem.
PowerTube 360 Battery
The 360 Wh PowerTube 360 weighs 2.1 kg and uses a slim in-frame design. It helps manufacturers build lightweight e-bikes with down tubes that look closer to those of conventional bicycles.
Intelligent Sensors
The system combines a bottom-bracket cadence sensor with wheel rotation and position sensors. These sensors help the motor detect starts, climbing, and cruising conditions and adjust assistance accordingly.
Controls and Display
The Hub Line supports Bosch's compact 5-button LED Controller and Intuvia 200 display, which features a 2.4-inch screen and USB-C charging.
ConnectModule and Flow+
GPS, cellular connectivity, and Bluetooth Low Energy support features such as theft alarms, motor deactivation, and location tracking through the Bosch eBike Flow App.
Bosch Hub Line vs. Mahle X20 vs. Active Line Plus
| Feature | Bosch Hub Line | Mahle X20 | Bosch Active Line Plus |
| Motor Placement | Rear Hub | Rear Hub | Mid-Drive |
| Max Torque | 45 Nm | 27 Nm | 60 Nm |
| Peak Power | 400 W | 275 W | 600 W |
| Drive Weight | 2.3 kg | 1.4 kg | 2.7 kg |
| Target Use | Urban commuting | Lightweight road/gravel | Trekking, cargo, city |
| Drivetrain Wear | Very Low | Very Low | Higher |
The comparison highlights Bosch's new two-part strategy. Mid-drive systems remain the stronger choice for high-torque applications, while the Hub Line focuses on lightweight urban riding.
What the Hub Line Means for Bosch's E-Bike Strategy
The launch does not mean Bosch is abandoning mid-drive motors. Instead, the company is expanding its portfolio to cover different types of e-bikes.
High-torque mid-drive systems such as the Performance Line CX and Active Line Plus remain suited to mountain biking, trekking, cargo, and demanding commuting. The Hub Line gives Bosch a dedicated platform for lightweight urban e-bikes.
It also puts Bosch into more direct competition with established lightweight hub-motor suppliers such as Mahle and Bafang.
Production e-bikes using the Bosch Hub Line are expected to begin appearing from major European and North American bicycle brands starting in late 2026 for the 2027 model year.
