The final verdict: Shimano Ultegra Di2

We don’t usually like to include question marks in headlines. It’s too ambiguous, and makes it too easy to get caught up in speculation.

Tom Boonen takes up professional bungee jumping? Well, I don’t know. It’s just a question, right? A question can’t be wrong.

Nonetheless, we broke our own rules and the headline of my Ultegra Di2 launch story last summer was “Ultegra Di2: better than Dura-Ace Di2?” This particular inquisitive headline seemed to be a legitimate question, and one we couldn’t quite answer after only a few rides on an unfamiliar bike. Now, eight months and thousands of miles later, the question mark can be removed:

Ultegra Di2: Don’t bother with Dura-Ace… for the most part.

Shift performance: DADi2 v. UDi2

Much of this is going to sound familiar, as my initial impressions of Ultegra Di2’s shift quality have remained largely unchanged. A winter’s worth of wear and tear hasn’t done anything to degrade the performance, though the drivetrain is now in need of a new chain.

When used with an Ultegra crankset, front shifting is absolutely indiscernible from DADi2. Anyone who tells you otherwise is trying to justify his or her more expensive Dura-Ace purchase.

It is still possible to shift under power, out of the saddle and even at extremely low cadences. The first chainring lift pin to pass by the chain on its rotation is also the last — it picks up the chain every single time and executes the shift to perfection. No grinding, no binding, nothing. Like its more expensive sibling, Ultegra Di2 offers the best front shifting available, bar none.

Swapping to a Dura-Ace crankset doesn’t improve shift speed, thought it does decrease drivetrain noise just a hair (and drops a load of weight).

Rear shifting is equally snappy and predictable. Here, though, the system does lose a bit to Dura-Ace Di2. It’s slightly louder, and dropping the chain down a cog feels less refined. When under sprint loads, each gear clunks rather than slides into place, as they do with DADi2. Regular shifts, under regular loads, are indiscernible from Dura-Ace.

Our guess is that a combination of increased flex in the rear derailleur and a less refined motor are the cause. Still, these are nitpicks — the rear shifting is still phenomenal.

The stats

The difference in weight between the electronic Ultegra Di2 and Dura-Ace Di2 parts is minimal, only 149 grams on our scale. Non-electric parts, like crankset and brakes, are not included in that figure.

On our scale, the shifters are 57g heavier, the front derailleur is 43g heavier, and the rear derailleur is 49g heavier.

Weights:
Shifters: 315g (DA: 258g)
Internal wiring harness: 43g (DA is very slightly heavier, depending on length)
Battery with bottle cage mount: 113g (70g without mount. DA uses same battery)
Front derailleur: 167g (DA: 124g)
Rear derailleur: 271g (DA: 222g)

Likewise, if we only compare the electronic parts, Ultegra Di2 saves about $1300 over Dura-Ace. An Ultegra Di2 front derailleur will set you back about $560, while Dura-Ace Di2 is about $780. Ultegra Di2 shifters are $445; Dura-Ace Di2 are nearly double that at $930. The rear derailleur sees a similar difference, with the UDi2 at $340 and DADi2 at $740. The UDi2 wiring harness is about $15 cheaper than Dura-Ace.

That’s an enormous price difference with a relatively small weight decrease and, as previously mentioned, virtually no improvement in actual performance.

A question of refinement

So what do you get from Dura-Ace Di2 for your extra $1300? Beyond the 149-gram savings, the biggest difference is in the group’s refinement. The perceived quality of Ultegra Di2 is certainly lower — the motors are bigger and bulkier, perhaps best described as bulbous. They are off-the-shelf items rather than the Shimano-designed, purpose-built, small and light motors found in Dura-Ace Di2. The finish on both Ultegra derailleurs, though full of polished bits and done up in a nice, dark anodized look, is still decidedly more plastic in places. The motor box on the front derailleur is the worst offender.

That story does not continue onto the shifters, which feel every bit as nice as Dura-Ace. Hood ergonomics and shift button actuation are identical between DADi2 and UDi2. The only difference between the two shifters lies in the materials used. Relative to Shimano mechanical systems, the overall girth of the handhold has been decreased. Combined with the ultra-light actuation, this makes both Di2 systems perfect for smaller hands.

You also get accessory shifters with Dura-Ace Di2, a feature that we place right alongside the phenomenal front shifting as a primary reason to go Di2. Dura-Ace offers bullhorn and aerobar shifters for TT bikes, top-mounted shifters for climbing, and drop-mounted buttons for sprinting. Ultegra offers none of the above.

Ultegra Di2 doesn’t get any of these features because it uses a new wiring harness, which is actually an enormous improvement over Dura-Ace. Ultegra Di2 can be mounted, plugged and unplugged as many times as you wish, no shrink-wrap needed.

Something new on the horizon

That leads us to the future, and another reason to avoid Dura-Ace Di2 now. Given Shimano’s usual product cycle, we know that a new electronic group is likely on its way for 2013. We are also quite sure, thanks to our industry moles, that this group will use the new wiring system debuted with Ultegra Di2, and will be 11-speed. We can assume that when this new Dura-Ace Di2 group is launched, so too will all of the accessory current shifters, and we can also hope that they’ll be compatible with current Ultegra Di2. Buttons don’t know whether they’re 11 or 10-speed, they just send a signal. It should all work.

The scoop

If we were to head to our local shop with the intention of building up a Di2 bike, the decisions would be easy. As long as having accessory shifters isn’t at the top of your list, and you can live with an extra 149 grams, Ultegra Di2 is the best option.

We’d buy the Dura-Ace crankset, which is significantly lighter, looks nicer, and is a bit quieter than the Ultegra crankset. We’d pick up the Dura-Ace brakes and cassette for the same reasons. But the Dura-Ace Di2 shifters and derailleurs, despite their flashier looks and slimmer figures, just aren’t worth the cash. The near complete lack of performance gain and actual decrease in user friendliness, plus the wiring harness’ imminent obsolescence, would have us looking elsewhere.