Sprag Clutch Bearing for Brose Alu S / Mag S Motor Crankshaft

One-way clutch bearing, also known as a sprag bearing, fitted to the crankshaft of Brose motors.

This clutch transmits force in one direction while allowing free rotation in the opposite direction, providing the crankshaft freewheel function. When worn or damaged, the motor may develop cracking or crunching noises, loss of drive, freely spinning cranks or intermittent engagement problems when force is applied to the pedals.

This is the metal version with a metal cage, offering a more robust alternative to the plastic-cage clutches used in some original motor versions.

Compatible with

Brose Alu S
Brose Mag S
Brose Drive S
Brose Drive T
Brose Drive TF
Brose S-Mag
Specialized Turbo motors equipped with an equivalent Brose drive unit

This clutch may also be found during repairs of Brose Alu C, T, TF and S motors, as well as Brose S-Mag motors, provided that the motor uses this type of clutch on the crankshaft. Before purchasing, we recommend checking the removed component or contacting us to confirm compatibility.

Specifications

Part number: PLB20127
Type: one-way clutch bearing / sprag bearing
Location: crankshaft
Version: metal
Dimensions: 40 × 48 × 11 mm
Application: internal repair of Brose motors
This is not the pulley clutch. The correct part number for that position is PLB20126.

Common symptoms of failure

A damaged crankshaft clutch may cause:

Internal cracking or crunching noises
Freely spinning cranks
Loss of internal drive
Absence or loss of the characteristic clicking sounds
Intermittent engagement problems when force is applied to the pedals
A feeling that pedalling force is not being transmitted correctly to the internal mechanism

Installation

Installation requires opening the motor and dismantling the internal crankshaft assembly. This is a technical repair that must be carried out using suitable tools and with experience in Brose motor repairs.

During installation, it is important to fit the clutch in the correct orientation and avoid damaging the crankshaft housing or contact surfaces. Incorrect installation may cause improper operation or premature clutch failure.

Important information about grease

One-way clutches require a grease specifically designed for this type of component.

Standard greases, low-friction greases and greases containing additives such as Teflon, ceramic, MoS₂ or other solid additives must not be used. These products may cause the clutch to slip under load and fail prematurely.

We recommend using a grease specifically designed for Brose motor clutches.

BiciFix note

This product includes only the crankshaft one-way clutch, part number PLB20127. It does not include any other bearings, the pulley clutch or the belt.

For a complete motor repair, it may also be advisable to replace the PLB20126 pulley clutch, the main bearings and the belt, depending on the condition of the motor.