KMC Bosch Gen 4 Super Narrow Chainrings

KMC Bosch Gen 4 Super Narrow Chainrings

The KMC Bosch Gen 4 Super Narrow Chainrings are designed specifically for Bosch 4th generation mid-drive e-bike motors. Made from hardened Chromoly steel, they combine high durability with precise chain engagement and efficient power transfer. Available in different tooth counts and chain-line options, they provide a straightforward replacement or conversion option for compatible Bosch Gen 4 e-bike drivetrains.

• Designed for Bosch Gen 4: Specifically developed for Bosch 4th generation mid-drive e-bike motors

• Hardened Chromoly steel: Provides a durable construction designed to withstand the demands of e-bike riding

• Super narrow design: Tailored to narrow KMC chains for precise chain engagement

• High efficiency: Designed to minimise unnecessary drivetrain friction and help maximise efficiency

• Multiple chain-line options: Available in 47.5mm, 50mm & 52mm chain-line configurations

• Direct mount: Designed for direct mounting with a 9mm offset

Bosch Gen 4 compatibility

These chainrings are designed specifically for Bosch 4th generation mid-drive systems, providing a purpose-built interface between the motor, chainring and chain. Recommended for use with KMC E-Series chains, including e1, e8, e9, e10, e11 and e12. The available chain-line options allow the correct configuration to be selected according to the bike's frame and hub requirements.

Hardened Chromoly steel construction

The chainrings are manufactured from hardened Chromoly steel to provide the durability required for regular e-bike use. The material is combined with a precise tooth profile designed to work with narrow KMC chains, helping maintain efficient chain engagement and reliable gear changes.

Will this chainring fit my bike?

Compatible with:

• Bosch Gen 4 drive systems

Available configurations:

• 40T – 52mm chain line

• 42T – 47.5mm chain line

• 42T – 50mm chain line

Check your Bosch drive unit generation and required chain line before purchasing.

Technical specification:

• Drive system: Bosch 4th generation

• Sizes: 40T, 42T

• Chain line: 47.5mm or 50mm or 52mm

• Material: Hardened Chromoly steel

• Mounting: Direct mount

• Offset: 9mm

• Colour: Black

• Recommended chains: KMC E-Series e1 / e8 / e9 / e10 / e11 / e12