Shimano Ultegra Di2 ST-R8170 12 Speed Shifter + Flat Mount Caliper SW Only Power readings are accurate within

Power readings are accurate within +/-1

and integrated radial spoke seats ensure perfect alignment

the "ZSG AGILE COMPOUND'' reduces rolling resistance by 12% and weight by 20g compared to the previous model

there is no need for you to carry a key

Endurance: 9-36T (9-10-11-12-13-14-16-18-20-23-27-31-36)

Shimano Ultegra Di2 ST-R8170 12 Speed Shifter + Flat Mount Caliper SW Only Power readings are accurate withinRoad riding has never been this much fun. The redesigned Shimano Ultegra Di2 ST R8170 12 Speed Shifter and Flat Mount Caliper has all new ergonomics, even more precise brake modulation and wireless electronic shifting, letting you focus on the next sprint, the next descent, or the next joke from your riding partner. Shimano's ULTEGRA ST R8170 brake levers bring enhanced modulation and control to every ride using Shimano's proven SERVO WAVE technology.