Shimano EW-SD50 Electric Wire Di2 250mm R0 the seat tube is a

the seat tube is a carbon ISP

They were developed to provide aerodynamic gains without the carbon price tag

Force vector data for analyzing and improving pedal stroke efficiency

This design also allows for a flatter plate

for perfect tubeless compatibility without rim tape

Shimano EW-SD50 Electric Wire Di2 250mm R0 the seat tube is aShimano Di2 e tube Wires Specifications Ultegra Di2 wires utilize Shimano's e tube technology; e tube is a two prong system and is NOT cross compatible with Dura Ace 7970 Di2 wiring All e tube wires may be used for internal or external applications Frame grommets for E tube internal wiring compatible frames are sold separately, see Shimano Frame Grommet Kit Electronic Shifter Extra Parts Mfr Claimed Weight TBC