Shimano SM-BB71-41B is a pressfit bottom bracket for installing a Hollowtech II crank in a road frame with a housing width of 86.5 mm. As usual with Hollowtech II, the bearings are 24 mm in diameter because this gives the best combination of rotational efficiency, rigidity, resilience, tightness and weight, even with press-fit bearings. SM-BB71-41B bottom brackets are recommended for older 10-speed road and cyclocross cranks.
