The Shimano FC-RS520 105 Double 12-Speed Chainset is a 2-piece crank that uses an outboard, 24 mm bottom bracket and features 2x12 speed 50-34T chainrings. It uses a 4-arm construction and is compatible with modern disc brake road frames. The chainring teeth have been developed to work in conjunction with Hyperglide plus 12-speed chains for increased contact to provide greater efficiency and improved power transfer.Lightweight 12-speed 2-piece design chainsetInnovative forged and anodised aluminium crank arms for minimum flexThe chainring teeth have been developed to work in conjunction with Hyperglide plus 12-speed chains for increased contact to provide greater efficiency and improved power transfer2-piece design bottom bracket bearings to be spaced wider apart, enabling the use of larger bearings and an increased axle diameterCan be used with Shimano external or press-fit bottom bracketsThe system allows for easier installation, adjustment, and maintenanceLightweight anodised alumin