VIDEO Review - Shimano Di2
article & images by Nick Salazar
Sep 7, 2011
Below is our full video review of Shimano's Di2 system. Below the video is a transcript that includes much more detail than what we could fit into the video, so feel free to read up on that if you want to expand on the points made in the vid. Thanks for watching!
By now, Di2 has been around for quite a while, and you've likely heard all about it on multiple road bike review sites. But I haven't seen a thorough, top-down look at this system from the Triathlete's perspective. And that's unfortunate, because ultimately, this system has more to offer triathletes than it does for road riders.
To begin with, let's start with what you already know. Di2 is built around the concept of a conventional drivetrain -- two derailleurs, front and rear, move a chain over two chainrings up front, and ten cogs on the rear cassette. The derailleur bodies are very much like Shimano's current 7900 Dura Ace bodies, and even borrow some of the same parts. The functionality of these parts is pretty much flawless. They work exactly like you'd expect. What's different, of course, is how those parts move through their gears. A cabled drivetrain relies on cable tension pulling the derailleur bodies in one direction, and powerful spring tension pulling in the other direction. Here's a cabled derailleur for reference. This one is the regular 7900 rear derailleur.
Di2's core concept revolves around replacing that cable tension with a simple motor that moves back and forth. And right there, even before going any farther, we've got a couple huge advantages. First of all, the fact that it's motorized means that, once set, your bike is good to go. Since the position of the derailleur doesn't depend on tension, it can never get out of whack. Gone are the days when you'd have to ride a couple hundred miles to let the steel cables stretch, then finally re-adjust once your derailleur got out of whack. Di2 just WORKS. You'll never snap a cable that's worn out, which is exactly what happened to Chris McCormack at Ironman Hawaii back in 2008, leaving him in the small chainring, unable to ride hard enough to defend his title from the previous year.
And what the motorized derailleur also gets you is amazing dependability, especially at the front derailleur. You can shift that thing under almost any circumstances without dropping a chain or missing the shift. Climb up a mountain and shift into the big ring up front, while severely cross-chaining in the back. It'll work. Like magic. Not that you really need to do that (or should for that matter), but it's good to know that even in the worst conditions, your front gears will work.
And that's all fine and dandy, but it's not what I really care about. All the cabled systems work perfectly well, even the cheapest of them. And even if you can't pull off ridiculous cross-chain upshifts, it's not a big deal. What IS a big deal are two features that Di2 has that the cabled systems can't touch. First and foremost, Di2 is an ergonomic DREAM. Shifting on this system is as easy as thinking. The shift buttons are placed right at the end of the pods, encouraging you to hold the shifters at their terminus like I recommended in my article on extensions.
And there's a little trick to how the shifters work. I've never heard anyone discuss it this way, but it makes life real easy. You don't have to remember up down, or left-right. It's really simple: the BIG buttons put you into a BIGGER gear, the SMALLER buttons into a SMALLER gear. I love it. And it's easier to think of it that way, because you can orient these shifters in a variety of ways: facing in is the norm, I have mine facing up since my pods are so close, and I've even seen some riders who have them rotating down slightly. Whatever suits you. Personally, I do like them facing up, though I don't really have a choice. With your thumbs right on the shift buttons, you don't have to do anything to get the gear to shift. Just a tiny little tap. Gone are the days of wrenching your arms to gain leverage over shifters that were originally built to mount on downtubes. This is how shifting was meant to be for triathletes. You stay perfectly aero, and shifting doesn't get in the way.
Speaking of shifting not getting in the way, this is where Di2 starts to shine even more. Because the shifting system is electronic, it's eminently modular. It's a trivial matter to wire in more shifters, because they're nothing more than in-line tact switches. If you're brave enough and have some soldering skills, you could even do it yourself. But fortunately, you don't have to. Shimano's aero brake levers have a second set of shifters built in, and they're a dream. The buttons are the same basic shape as those for the extension pods, and they're in the perfect spot for your thumbs when you're out on the base bar.
Granted, a triathlete should spend most of their time out in the aero extensions. But when you come out of the extensions, it's because you're cornering or climbing. And both of those are situations in which you really WANT to have shifting control. It's really, really nice to be able to have it. In a racing situation, it's a no-brainer -- shifting out of a corner will put you in the perfect gear to get going again, saving you time versus being overgeared. But in training, this just makes life better. You can go tackle a climb without worrying about what gear you want to be in, or having to awkwardly shift out at the extensions. Di2 has made tri bike more fun!
At What Price?
Innovation often comes at a price, figuratively and literally, and Di2 is no exception. It's made headlines for its top-pf-the-line tech, but also for its top-of-the-line price. At present, triathletes can only get Di2 at the Dura-Ace level. And the group retails for around $3500, or nearly double that of standard Dura Ace, or SRAM Red. On the other hand, many of today's tri bikes come with a lot of components already on them. All you need to upgrade to a Di2 tri group are two derailleurs, extension shifters, brake lever shifters, cables, a battery, and a charger. These can be had for closer to $2000 if you shop around. Still quite expensive, but a lot less than getting the full group.
The other big drawback is the weight. Some parts are actually quite light - the shifters, for example, are just 90 grams, nearly 50 grams lighter than SRAM RED. But, there's a penalty with Di2 in the extra weight of the motors, and the battery. And there's really no way around those. Ultimately, the difference between a full Dura-Ace Di2 group and a SRAM RED group is a whopping 450g - a full pound! So if you're racing hilly courses, you'll have to turn elsewhere to save weight.
Some people will argue that setup is more challenging with Di2, but I think the opposite is true. Relying on an electrical connection rather than cable tension actually makes things simplet, although perhaps more meticulous, to set up. You have to be more careful not to short anything out or screw something up, but I thoroughly enjoyed the build process.
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