Shimano Di2 Electronic Drivetrain Questions
Posted by Ashley on Dec 26, 2011 | Product Reviews
As seen in November's Road Bike Action
So what does it all weigh?
Keep in mind these weights include all parts- from shifters to derailleurs, cranks to brakes- and everything else one might need, including a chain, battery and wiring connectors (if applicable). The weights for Shimano's four priciest groups (supplied by Shimano) are as follows:
- Dura-Ace Di2: 2,219 grams
- Ultegra Di2: 2, 482 grams
- Dura-Ace (mechanical): 2,149 grams
- Ultegra (mechanical): 2,402 grams
What about the gearing?
Shimano designed the Ultegra Di2 fron derailleur to work specifically with the Ultegra 6700 cranksets, both standard (53/39) and compact (50/34) varieties, but it will still work fine on equivalent offerings from other manufacturers. Since the Ultegra Di2 will only accommodate two chainrings, fans of triple cranksets are still out of luck as they were with the Dura-Ace Di2. Ultegra Di2's rear derailleur will accommodate up to a 28-tooth cog.
Just like the Dura-Ace Di2, Ultegra Di2 has absolutely no limits for 'pre-shifting.' While coasting and not pedaling, you're free to shift gears to your heart's content, even all the way across your rear cassette, and the rear derailleur will engage the gear change once you start pedaling again. At the same time, the front derailleur will utilize its 'auto trim' feature and angle itself as necessary so that when the gear change occurs, your chain line will be as optimal as possible.
How long will the battery last?
The Ultegra Di2 system uses the same battery as the Dura-Ace Di2. It takes 90 minutes to achieve a complete charge, and Shimano guarentees the battery will be good for at least 500 full recharges during its lifespan. As to how long the battery will run between charges, that largely depends on your shifting frequency and riding conditions (extremely cold weather will drain the battery faster than hot-weather conditions under similar shifting frequency). Shimano is hesitant to lock in specific time frames for battery run-time, but our experience indicates that you'll go anywhere from three to six months between full charges. But, we'd recommend popping your battery into its charger every few weeks, however, just as you would recharge your cycling computer, GPS unit or cell phone.
So how do we think it works?
The biggest difference between Shimano's mechanical shifters and the electronic versions is that both the shifter and brake levers remain stationary when making a shift. The push-button shifters found on the outside face of each lever redefine the concept of 'light action.' The bottom line is that no matter the gear selection and no matter the load on the pedals, the battery-assist shift will happen at any place and any time.
Those who test rode the Ultegra Di2 at Shimano's launch in Aigle fell into one of two camps: those who had previously ridden the Dura-Ace Di2, and those who had not. Those with absolutely zero Di2 experience were quick to rave about the Ultegra Di2's smooth, consistent shifting, as well as the front derailleur's auto-trim feature, which virtually eliminates chain rub. The first-timers' experience with the Ultegra Di2 was a revalation, akin to what the second camp's initial impressions were of the Dura-Ace Di2. For those with the good fortune to have ridden Shimano's first electronic drivetrain beforehand, the impressions were positive on the whole, with particular enthusiasm due to a high performance-to-price ratio.
Indeed, riding with the Ultegra Di2 feels just like riding with the Dura-Ace Di2. Although Shimano says the shifts are just as quick between the Ultegra and Dura-Ace, we did detect the shift feeling a mere millisecond slower. Most importantly, the shifting is just as consistent, and we experienced no troubles during our two days of test riding. Like the Dura-Ace Di2, the Ultegra Di2's most impressive attribute is its front derailleur, which makes its shifts under load without the fear of dropping a chain or causing any sort of calamity. As is the case with Dura-Ace Di2, sequential shifts are still the order of the day, so you can't jump gears. But because the shift buttons equate to clicking bottons on your computer mouse, you can still shift multiple gears in rapid succession with minimal effort.
Yeah, but what does it cost?
A set of Ultegra Di2 electronic components will run you $1,600 in retail, which includes derailleurs, shifters, battery, wires and connectors, but doesn't account for mechanical items like cranks and brakes. By comparrison, the 2012 Dura-Ace Di2 electronic parts selection should retail for around $2,500. Projected prices for complete 2012 bikes outfitted with the Dura-Ace Di2 range from $7,000 to well over $10,000. Ultegra Di2 equipped bikes should sell for around $4,000-$6,000, which will be just about what a mechanical Dura-Ace equivalent bike will cost.