Highest riding comfort: BBRS and BBRTTS - nd generation sensor bottom brackets for E-bikes

Schaeffler at EUROBIKE 2013 (Hall A3, Booth 807)

Highest riding comfort: BBRS and BBRTTS - 2nd generation sensor bottom brackets for E-bikes

Ready-to-fit sensor bottom brackets from the FAG brand have a high load capacity and are simple to fit. Their reliable and very high resolution signal processers ensure the highest level of riding comfort on e-bikes. Schaeffler is now presenting the 2nd generation of both the basic model BBRS and the high-end variant BBRTTS. The torque sensor bottom bracket unit BBRTTS has established itself as one of the top models on the market and offers increased riding comfort, efficiency and range. The BBRTTS determines the total torque from the sum of the pedal force from the left and right pedals. The bearing unit detects the riders requirement for motor assistance depending on the situation and controls the output accordingly. Schaeffler is also presenting the basic sensor bottom bracket model BBRS in an advanced variant. It enables non-contact measurement of speed and direction of rotation and offers the shortest reaction times from the control system with 36 speed impulses per rotation of the crank.

Sensor bottom bracket BBRTTS: Control by means of 72 sensor pulses per revolution

Besides the direction of rotation and speed, measurement of the exact torque produced by the rider during pedaling is a prerequisite for precisely determining the power requirement. The additional drive power provided by the electric motor is controlled principally by the torque sensor system in the bottom bracket. Up to 72 impulses are generated per revolution of the spindle.

The FAG torque sensor bottom bracket BBRTTS has now been revised and further improved after its debut in 2010. The second generation BBRTTS is characterized in particular by a speed signal with a higher resolution and a torque sensor system with improved accuracy. These characteristics are a prerequisite for the quality of the output signal and rapid response of the motor control system. The rider is thus provided with optimum assistance in every situation. This is associated not only with increased comfort, dynamics and riding pleasure but also with maximum efficiency, which results in an increase of the range.

Two different non-contact measuring methods are used in the compact bottom bracket unit. The speed and direction of rotation are measured by a Hall effect sensor, while torque measurement is carried out by means of a magneto-elastic method. The measurement range is between 0 and 100 Nm with an accuracy of up to one percent. Up to 300 Nm is optionally available in professional applications, for example, for performance measurement on racing bicycles. Additional applications are ergometers in the fitness or rehabilitation sectors.

The FAG torque sensor bottom bracket BBRTTS is used, for example, in high-performance drives from Bosch and TQ-Systems.

Sensor bottom bracket BBRS: Control by means of 36 sensor pulses per revolution

As the basic model, the compact sensor bottom bracket BBRS offers non-contact measurement of speed, direction of rotation and angle of rotation. 36 impulses are generated per revolution of the spindle. This significantly higher resolution enables precise control due to significantly shorter reaction times during activation and deactivation of the drive. The drive can respond much more precisely to the individual riding habits of the rider and thus provides optimal assistance. The system is also capable of distinguishing between pedaling in a forwards or backwards direction and providing this information in the output signal.

In contrast to openly accessible and thus easily damaged solutions (magnetic disk with a Hall sensor), the FAG sensor bottom bracket BBRS is a fully encapsulated system that fits in the same space as a conventional bottom bracket. The sensors are extremely well protected, are not exposed to any disruptive influences and are completely maintenance-free. The system is ready for immediate operation without any adjustment after fitting.

Smooth running and corrosion protection

Like all bottom bracket units from FAG, sensor bottom brackets are characterized by excellent smooth running characteristics. This is facilitated by the optimized bearing arrangement, in which the bearings are not clamped in the frame. Schaeffler also uses FAG Generation C deep groove ball bearings, which have around 30 percent less friction compared with previous models. Numerous components in the area of the shaft are also coated with Corrotect corrosion protection developed by Schaeffler.

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