Shimano ST-R7170 105 Di2 Hydraulic Disc STI Shifter / Brake Set

Shimano’s latest electronic Di2 105 shifters communicate wirelessly with the frame’s derailleur and battery system, making fitting easier and the front end cleaner. Although the levers are in exactly the same place as with the mechanical STI units, all that is needed to switch chainrings is a light press on the lever for an instant change. When a different sprocket is selected at the rear, the front derailleur also moves if necessary to prevent chain rub. There are also two different shifting programmes that can be selected, with full and semi synchronised modes providing two different ways to automatically ensure that optimal cadence is maintained.

The lever units also house the reservoir for the hydraulic brakes, with the caliper featuring an auto adjust to maintain brake feel and performance as the pads wear down. Two 22mm ceramic pistons in the caliper provide plenty of power and modulation whilst the finned L05A resin compound pads have excellent temperature regulation and bite. There is a wide range of reach adjustment for the brake lever so that all hand sizes can be accommodated.