The Shimano Ultegra Di2 electronic groupset is by far and large the most anticipated product launch of the last year, if not longer. When the Dura-Ace Di2 launched three years ago, it also received much praise for its innovation, and flawless shifting; it truly was a giant leap forward in road componentry. However, there haven't been any subsequent releases reflecting the three years' worth of user feedback and engineering tweaks. Enter the Ultegra Di2, the second generation of Shimano electronics.

After a quick comparison of both groups, our main finding are:
• The functionality is exactly the same
• The cost difference is the lack of carbon & titanium bits found on the Dura-Ace, and a more off-the-shelf motor system
• The battery won’t last as long (at least 3500km before charging, versus up to 5000km with the Dura-Ace)
• A simpler, more streamlined wiring system (2 wires instead of 4, plus coaxial-type connection for a simpler, more secure connection which doesn’t need a precise wiring orientation)
• A smaller diameter wire means a less obtrusive presence on the bike
• The only interchangeable part between the Ultegra & Dura-Ace Di2 is the battery
• The STI shifter blade is aluminum (not carbon, like the Dura-Ace), and it has a reach adjustment screw to bring the shifter closer to the bar (for riders with smaller hands)

Another new Ultegra twist is the pedal (not included in this package), now built with the same carbon composite injection-molded body as the Dura-Ace. It has a cartridge-style, 2-bearing system, with a non-tapered chromed steel axle (meaning 2mm of extra stack height).

The crankset, cassette, chain, and brake calipers remain unchanged from the regular Ultegra 6700 series components.

While the Dura-Ace Di2 remains the benchmark in component innovation, its price tag still keeps it in the "wish list" column for many cyclists. But with the Ultegra Di2 now offering identical performance at almost half the price, we truly believe this is when the 'electronic age' of bicycles begins in earnest, and electronic components will become widespread.