A practical replacement for MTB riders using a 68 or 73 mm English/BSA shell with Shimano HOLLOWTECH II 24 mm cranks.
The Shimano Deore BB-MT501 is a threaded external bottom bracket for MTB frames with 68 or 73 mm shells. It is designed for Shimano HOLLOWTECH II 24 mm spindle cranksets, making it a suitable replacement when your existing bearings are worn or rotation has become rough.
Its outboard bearing system supports efficient power transfer while balancing stiffness, weight distribution and pedalling stability. The bearing layout also helps provide smooth rotation, and better sealing performance helps protect the moving parts from the dirt and moisture encountered during regular mountain-bike riding.
With aluminium threaded cups and a familiar English/BSA interface, this is a sensible choice for a straightforward service or drivetrain refresh. Before ordering, check both your frame shell width and crank spindle standard to confirm compatibility.
68/73 mm shell compatibility
Fits MTB frames with either a 68 mm or 73 mm threaded bottom bracket shell.
English/BSA threaded interface
Uses the common English threaded frame standard for a direct replacement on compatible frames.
HOLLOWTECH II compatibility
Designed for Shimano HOLLOWTECH II cranksets with a 24 mm spindle.
Outboard bearing system
Positions the bearings outside the shell to support efficient power transfer and stable pedalling.
Improved sealing
Better sealing performance helps the bearings cope with the dirt and moisture associated with MTB use.
Efficient rotation
The bearing design provides better sealing and rotation for high driving efficiency.
Aluminium threaded cups
Aluminium cups provide the threaded external interface in a practical, serviceable format.
General
Features
HOLLOWTECH II
The outboard bearing system supports efficient power transfer with a strong balance of stiffness, weight and rotational performance. Its bearing layout also improves weight distribution and pedalling stability.
Shimano is a Japanese component brand founded in 1921 in Sakai, Osaka. The company began with bicycle component manufacturing and has grown into a global business focused on bicycle components, fishing tackle and rowing equipment, while keeping its headquarters in Sakai.
In cycling, Shimano is best known for building complete component ecosystems that span road, mountain, gravel, commuting and e-bike use. Its range covers drivetrains, brakes, wheels, pedals, shoes and related parts, and the brand has had a long presence in Australia through a local business established in Sydney in 1992.
