Originally developed to build on Shimano's top level component group Dura Ace, the Di2 electronic shifting system changed the roadie game with unmatched speed, accuracy and precision. Now with its third iteration, Di2 makes its debut for internal gearing systems by joining Alfine, Shimano's premium-level component group for city cycling. The Alfine Di2 Shimano introduces a whole new way of thinking about how a commuter bike can be built.
Like traditional internal hubs, the Alfine Di2 internal mechanism is made up of a series of stepped planetary cogs in an oil bath that when engaged replicate the resistance of multiple high or low gears. Rather than relying on wires physically pulled at different forces to leverage gear change, Di2 releases a burst of electricity that engages a small, light weight motor mounted on the outside of the hub, increasing reliability and performance while decreasing the chance of mis-shifts.
As the first electronic-controlled internal hub, the 11-speed Alfine Di2 increases city commuting efficiency with a wider gear range for terrain adaptability—our road-test conquered the hills of San Francisco with ease—on a single lithium ion battery charge estimated at more than 1,000 miles, which is longer than Ultegra and Dura Ace iterations. Plus, the sealed internal hub drive train can withstand much harsher weather conditions with less wear and tear than a traditional gearing system.
Another first for internal hub systems, Alfine Di2 offers two shifting options to accommodate both flat handlebars with a push button system and dual-control levers for traditional road-style drop bars, both compatible with mechanical disc brake systems. Sitting atop these bars you'll find a specially designed LED readout ready to inform of both battery life and current gear status. The advent of these options make for a sleeker new school commuter unlike the clunky wire-ridden beasts of yesterday.
Not to be outdone, Alfine Di2 not only boosts performance to a level never before seen, it improves on aesthetics as well. By taking advantage of the new generation of E-tube internal wiring and the option for an internal seat post mounted battery the already clean design of the Alfine group is made even more sleek—an underrated tack in making a city bike less of a target for theft.
Just announced earlier this month, the Alfine Di2 component group will be available Fall 2012 in specialty bike shops, direct through Shimano dealers and presumably on a range of higher end comfort commuter bikes from big name manufacturers.