The Shimano Deore SM-BB51 is a durable threaded Hollowtech II bottom bracket for MTB and trekking cranksets with a 24 mm spindle.

• Hollowtech II external-bearing design
• BSA / English threaded, for 68 mm and 73 mm shells
• Fits 24 mm Hollowtech II crank spindles
• Includes 3 x 2.5 mm spacers
• Sealed bearings for long service life