Shimano

Di2 Battery

Running an electronic drivetrain isn't technically cheating, but super-smooth and reliable shifting might make you feel like you're doing something a little illicit. Don't sweat it, though—the haters are just jealous. The only drawback to electronic shifting is the possibility that it'll run out of juice and leave you stuck, but Shimano's Di2 Battery puts an end to your drained-battery worries, with an average life of 1000 miles. A battery life indicator is activated by depressing the shifter paddle for a few seconds, and displays flashing or solid red or green lights, depending on the remaining charge. The Di2 charger (not included) fires the battery up to full charge in 1.5 hours, and the battery will charge about 300 times before you have to think about replacing it. Shimano also hooked the Di2 up with a sturdy and convenient bottle-cage mount to secure it to your bike, and built in a sleep mode to save battery life when you're not shifting.