Press-Fit BB uses a 24 mm shaft and bearings, because the 24 mm diameter shaft and bearings offer the best balance between rotational performance, rigidity, strength, sealing, weight, and for the Press-Fit type.

Product features
Use: MTB, Downhill, Freeride
Model: SM-BB71-41C
BB-Type: Press Fit BB107 (41x24mm)
Press-Fit BB shell width: 104.5/107mm
Shell diameter: 41mm
Compatibility
Saint FC-M825
ZEE FC-M645
Material
Resin
Weight
73g

HOLLOWTECH II Technology
The concept of HOLLOWTECH II technology focuses on producing a superior crank that will maximize the rider's power transfer. The stiffness of the crank ensures pedaling efficiency, while the weight of the crank, a key component of the crank, you want lightweight, helps in cycling longer distances over which the rider needs to pedal more. Of course, SHIMANO has strived for the optimal balance between the conflicting stiffness needs while producing a lightweight crank. HOLLOWTECH technology is an ultra-lightweight hollow crank created by SHIMANO with the company's proprietary forging technology that also maintains stiffness. The addition of HOLLOWTECH II technology integrates the bottom bracket shaft with the correct crank for more stiffness and weight savings to achieve high-dimensional balance. The outboard lower arm bearing system provides better weight distribution and greater stability to the pedals, allowing for more efficient power transfer.