Description: 【Material】: This bike bottom bracket is made of aluminum alloy, ensuring a long lifespan and reliable performance for your bicycle. 【Versatile Use】: The thread type bottom bracket is suitable for both mountain bikes and road bikes, making it a versatile addition to your cycling equipment. 【 Specifications】: The BB91 thread type bottom bracket fits 6.8cm-7.3cm/2.68inch-2.87inch bottom bracket shell with a tooth pattern of BC1.37. It comes with three 2.5mm spacers for use as needed. 【Easy Installation & Operation】: With an inner diameter of 24mm/0.94inch, this bicycle bottom bracket is designed for easy installation and operation on 6.8cm-7.3cm/2.68inch-2.87inch bottom bracket shell. 【Design】: Featuring ceramic bearings, this bike bottom bracket ensures smooth pedaling and improved cycling efficiency while reducing weight for optimal performance. Specification: Material: Aluminum Alloy Package Includes: 1 Bike Bottom Bracket Note: Please allow slightly errors 1-2cm differences due to manual measurement.