A strong choice for mountain-bike riders replacing a worn HOLLOWTECH II bottom bracket on a BSA-threaded 68 or 73 mm frame.
The Shimano SM-BB93 is a threaded BSA bottom bracket for mountain bikes using HOLLOWTECH II cranks. It fits 68 mm and 73 mm shells, with the required spacer arrangement set according to the shell width.
Its outboard bearing layout gives the crankset broad support outside the frame shell, while the sealed bearing area is designed to maintain smooth rotation and improve durability in regular mountain-bike use. At just 73 g, it is a useful replacement when you want dependable bearing support without adding unnecessary weight.
Real-world feedback is consistently positive about its quiet, smooth operation, straightforward replacement and long service life. One owner reported replacing a previous unit after six years, while others highlighted smooth running and compatibility with 24 mm crank spindles.
HOLLOWTECH II fit
Designed for HOLLOWTECH II cranksets, making it a direct option for compatible Shimano mountain-bike builds.
68 / 73 mm shell support
Fits the two common threaded mountain-bike shell widths, with spacers arranged to suit the frame.
BSA threaded interface
A conventional threaded installation for frames using a BSA bottom-bracket shell.
Outboard bearings
The external bearing position provides broad support for the crankset and helps maintain pedalling stability.
Smooth rotation
Built to deliver smooth running through the crankset, with real-world users describing it as quiet and smooth in service.
Improved sealing
Sealing around the bearing area helps protect the unit and support durability during mountain-bike use.
Low weight
At 73 g, it keeps the replacement light while retaining the practical features expected from an XTR bottom bracket.
Installation guidance
Shimano specifies dedicated HOLLOWTECH II tool combinations and a 35–50 N·m cup-tightening range for installation.
General
Compatibility
Dimensions & weight
Features
HOLLOWTECH II
The outboard bearing system supports efficient power transfer with improved weight distribution and pedalling stability, while balancing stiffness, weight and rotating performance.
Outboard bottom bracket bearing system
Positioning the bearings outside the frame shell provides wider bearing support, helping improve stability and power transfer through the crankset.
High-precision sealing
Precise sealing around the bearing area helps improve durability and maintain smooth rotation over extended use.
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.
