Product Description The Shimano Dura-Ace BB-7700 bottom bracket has proven itself over decades The Shimano Dura-Ace BB-7700 is an Octalink bottom bracket with 8-splined interface that has been in service for decades. It fits perfectly with the Dura-Ace Track crank FC-7710. Its cold-forged hollow axle increases rigidity. Specifications:Application:Track, RoadSeries:Dura-Ace 7700Type:BSA, ITAShell Width:68 mm, 70 mmAxle Length:109.5 mmAxle Type:Octalink (Road)E-Type Compatibility:noChaincase Compatibility:noTechnical Information:Bearings:steelAxle Material:steelBottom Bracket Cup Material:aluminiumCompatibility:Octalink crank arms with eight-speed splines for shorter grooves (Octalink MTB) Recommended for: Dura-Ace FC-7710Features:8-splined interface of bottom bracket axle and crankcold forged hollow axle for increased stiffnessdiagonally tapered ribs for permanent load-bearing connection of bottom bracket axle and cranksmaintenance-friendlymore efficient power transferTechnology:Octalink In Shimano's Octalink system, the bottom bracket and crank are connected by an 8-tooth contact surface. This provides greater rigidity and greater load capacity, especially compared to conventional square systems. Models:BSA 68x109.5: Threads:BSAShell Width:68 mmAxle Length:109.5 mmManufacturer Number:I-BB7700B09N ITA 70x109.5: Threads:ITAShell Width:70 mmAxle Length:109.5 mmManufacturer Number:I-BB7700I09NContents:1 x Shimano BB-7700 bottom bracketOrder Together:bottom bracket tool TL-UN66 or TL-UN74-S in combination with wrench TL-FC31 Weight: universal | BSA: 173 g Manufacturer: Shimano Europe B.V. High Tech Campus 92 5656 AG Eindhoven Netherlands info@shimano-eu.com