If you want the skinny on how Ultegra Di2 operates, and how it differs from Dura Ace Di2, then Mat's got that pretty much covered in yesterday's first ride piece. Since then we've been riding the bikes some more, up hills and down, and here's my thoughts on the new groupset thus far.
Firstly, it's more or less indistinguishable from Dura Ace Di2, both in function and in the look of the groupset. Given that it's half the price, if you are in the market for electronic gears (more on that in a bit) then it's a total no-brainer: you buy these, not Dura Ace, especially since we're assuming that Shimano will stick with the 2-core cabling for later revisions. Unless the 250g difference in weight matters to you that much. I weigh 100kg. It doesn't matter that much to me.
Spin the bike up to speed and have a fiddle with the buttons and everything works perfectly. Once you've committed the controls to memory they're as easy to locate and use as anything else, and since you're not mechanically shifting the mechs it's even easier. This is especially noticeable with the front mech; the motor's bigger in that one because as we all know, it takes more oomph to make front shifts. Not any more: that's the biggest draw. In fact, some of the talk on the press camp has been along the lines of, "can I have an electronic front and a mechanical rear?"
And why would you want a mechanical rear? Well, the gains at the back aren't as great. It does make good shifts, every time, don't get me wrong. But sometimes when you're climbing and you know the next shift up the cassette is going to be a bit graunchy, you feather it in to ease the load on the chain. Di2 doesn't allow you to do that, so you have to be careful in other ways, easing off a touch on those problem shifts. If you don't, you'll make it crunch, but it'll still make the shift, every time. It's just a different way of doing things and it's neither better nor worse, it's just that it's not immediately and noticeably better than a well-adjusted mechanical mech.
The front mech has two big wins: it shifts much more easily and it trims itself. The back doesn't have an obvious big advantage over mechanical, the gains are more marginal: the shifts are fast and accurate every time and the cables don't stretch. You can't sweep the lever through three or four ratios if you suddenly hit an unexpected climb – though probably you'll just get used to tapping the button quickly in an emergency – and it's a touch slower to drop it right down the block too.
Battery life has been mooted as an issue here; it isn't one really, or at least it shouldn't be. So long as you put a battery check on your pre-ride checklist then you're fine: if it's flashing red, just remember to bung it in the charger when you get back, unless you're out for 150 miles or more in which case you'll need to give it a quick blast before you go.
Dura Ace Di2 had two major problems, as far as I was concerned: it was fantastically expensive and difficult to fit in a home workshop. Ultegra Di2 has addressed both: It's half the price and the new plug-and-play cabling, which uses a widely accepted protocol for the shift commands, is much easier to fit. There's no heat shrinking, you just click the wires in place and you're off. Shimano say it's fully waterproof from the off. It's fair to report that we had one of the test bikes fail on the test rides, due to water ingress, probably in the battery holder. But these are still pre-production samples.
We've talked to people who have been using Dura Ace Di2 on cyclocross bikes and it's continued to be perfectly functional long after the brakes have stopped working. It's fairly easy for water to get into a cable system and stop it from being efficient; if an electronic system is well sealed it should be practically maintenance free. Although Ultegra Di2 will appeal predominantly to the sportive set, there's a decent argument that it's as useful as a low-maintenance option for a day-to-day bike. Albeit an expensive one. It may be that years from now the draw of electronic shifting will not be the shifts themselves, but the low maintenance of the system as a whole. It's a bit early to say.
So do you need it? No. You don't need it, so let's add it to the big pile of stuff – GPS units, carbon bottle cages, Rapha clothing, torque wrenches and so on – that you don't need. But actually, would quite like. To say Di2 is aspirational and that we don't need it is missing the point, and it's certainly not true for everyone. Ultegra Di2 will cost less than mechanical Dura Ace, and that's not the most expensive groupset available by a stretch. How much do you want to spend on a bike? Canyon do a Dura Ace equipped full carbon bike for £2,649, so Ultegra Di2 bikes aren't going to be stratospherically expensive. Groupset technology always trickles down, and Di2 is trickling down quicker than most. How long before it reaches 105? Tiagra? How far will it go? We don't know. But it's probably here to stay.
*It's really not that far to France from here
Dave is a founding father of road.cc, having previously worked on Cycling Plus and What Mountain Bike magazines back in the day. He also writes about e-bikes for our sister publication ebiketips. He's won three mountain bike bog snorkelling World Championships, and races at the back of the third cats.