Shimano’s asking price alone assures that most riders who take offence to its Di2 XTR electric shifting system do not factor into its marketing strategy. Di2 XTR, if you can find it, will run you about $2800 for a complete two-by-eleven drivetrain. That’s a lot of cash for a small pile of parts. Consider that in a recent PB poll, an overwhelming number of responders placed the optimal MSRP of a mountain bike capable of elite-level performance between 3000 and 4000 dollars, and you may begin to realize that Shimano probably did not make Di2 for you. Why You Need Di2 XTR
Shimano Di2 XTR: Long-Term Review
Di2 XTR exists exclusively for the cycling’s top-level competitors and for top-level recreational shoppers. Unless you count yourself among them, your opinions about batteries on bikes, non-standard parts and Shimano’s pre-determined gear selections are wasted breath. Whether you are a naysayer or a supporter, the bottom line is that Di2 XTR shifts better and is easier to use than any derailleur bicycle transmission that has ever been mass produced for cyclists. Those who presently ride Di2 will no doubt agree that: “No. You don’t need it.” And, “Yes. You do want it.” Lazy readers can stop right here, because this entire story is summed up in those few short phrases. Riders who are curious about how Shimano’s push-button shifting performed over a long-term test, however, should find this review interesting.
Forget how Shimano’s electric shifting operates, clear your mind of its cost and perceived complexity, and you will find it very hard not to like. The rotary action of the shift levers are a near-perfect ergonomic match to the natural sweep of the thumbs. Shimano’s artificial mechanical click provides audible and tactile assurance that a shift has been called for, and (providing that it has been set up correctly) Di2 responds with a perfect shift - every time. There is no mechanical connection to the derailleurs. You ask for a shift and then pedal, knowing that, regardless of how much pressure you are putting on the pedals, or how your human form may be twisted around the cockpit, that Di2 will manage to shift to the next gear. There is no “maybe” in Di2’s vocabulary.
|My mechanical drivetrain does the same things - at one fourth the cost.|
We imagine that we can shift our mechanical transmissions with resolute perfection, but that is simply not true. A few months on Di2 are all it takes to realize how much knowledge and learned behavior a cyclist must assimilate before he or she can operate a mechanical derailleur system with surety. Consider for a moment, the actions that take place during a conventional cable actuated shift to a lower gear option:
First, you must remember to depress the lever just far enough to shift one gear (both SRAM and Shimano levers can shift multiple gears in one throw). Next, you listen for sounds that the mechanisms emit which give you verification that the shift is taking place. Then, you hold the lever in position until you are convinced that the shift is finalized and finally, you release the lever and check leg pressure to reconfirm that you have selected the proper gear.
All of the above may have been committed to muscle memory and subconscious action, but that does not take away from the fact that the rider must participate in each step in order to complete a perfect shift. So far, we are only using rear shifting as an example. The front changer’s reverse function, along with its distinctly different feel and sound, add further complexity to shifting a mountain bike’s transmission.
When a conventional shift lever is releasing cable to shift to a higher gear (smaller cog), it operates very much like Di2. You flip the trigger lever and forget about it, leaving the mechanisms to take care of everything necessary to make the shift. The only action required from the operator is to check leg pressure to confirm that he or she has selected the correct gear. Imagine the same action in both shifting directions, with an added measure of smoothness and precision, and you get Di2.
Conventional shifting also puts the burden of selecting the optimal gear range from a wide variety of options – some of which can create problems, or in extreme cases, destroy the drivetrain. For example: Di2 can shift a wide-range two-by or three-by drivetrain using a medium-cage derailleur, with a chain that is too short to operate when the transmission is cross-chained in the largest sprockets and NEVER make the mistake of shifting into the forbidden combinations.
Customization is also a unique attribute of Shimano Di2. By downloading Shimano’s e-Tube Project software to your PC (not ready for Macs, yet), you can program the shift levers to command any of the system’s functions. You can program Di2 shift like the paddles of a sports car with one side for up-shifts and the other for downshifts. You can program either the right or left-side buttons in Synchro mode to automatically shift both the front and rear changers. The functions of either button on one shift lever can be reversed, and given single or multi-shift powers.
Confusing? Having so many options can be daunting, but like suspension settings, you will quickly discover that only one or two choices are useful. I found E-Tube software to be easy to use, but Shimano has done its homework. After messing with a number of custom options, I opted to return to the default Synchro mode, where it stayed until I returned the bike.
It’s easy to imagine why cross-country pros, (who, I assume, are pretty handy with mechanical shift levers), have embraced Di2. Shifts are easier and more accurate, so a rider can confidently change gears more often to manage power output and, perhaps more importantly, make fewer errors towards the latter stages of a race when fatigue dulls reflexes and judgement. For both professional and rank-and-file-trail riders, Di2 simply means never having to worry about shifting. You place the order, turn the pedals and, “bzeeb, bzeeb, bzeeb” - Di2 handles it.Why You Don’t Need Di2 XTR
Truth is, Di2 doesn’t bring any major revolutions to the table. Shimano’s conventional XTR shifts well enough to make almost any rider happy. Di2 simply offers better shifting, and a Synchro Shift feature that allows two and three-by XTR drivetrains to be operated by one set of levers. Di2 in the 22-speed, two-by-eleven configuration offers 13 well-spaced gear options. That works out to one gear lower and one slightly higher than the SRAM one-by-eleven. I was also riding SRAM X1 during the long-term test period, and I put a lot of time on Shimano’s conventional XTR in both two-by and a one-by arrangements. In the end, I can comfortably state that, unless you absolutely need (or want) slightly better shifting and a wider, more evenly spaced gear range than a SRAM X1 drivetrain offers, you don’t need Shimano Di2.
Why state SRAM as the alternative instead of XTR? Because a Di2 two-by transmission, used in Synchro mode, is its direct competition. Paradoxically, once you have experienced the self-trimming feature and ease of shifting that Di2 brings to the table, you would never want to use a mechanical front derailleur. If Di2 can be considered revolutionary, it is because it demonstrates how cumbersome a mechanical front mech’ is – and thus furthers the case for eliminating them. But, presently Shimano lacks a competitive one-by option for XTR. If one compares gearing options, chain retention, and shifting stability of the two brands in a one-by arrangement, SRAM is the clear winner over Shimano in all three categories.
Shimano has been awarded patents for narrow-wide chainrings and has recently released an 11 by 45-tooth eleven-speed cassette that operates with Di2, so there is evidence that its mechanical and electronic one-by options will soon close the gap to SRAM.
But, as it stands, if you want a one-by drivetrain, buy SRAM - and if you want a two-by drivetrain with closer-spaced shifts and a slightly wider gearing range, buy Shimano Di2. Both give you best-in-category performance and both free up the left side of the handlebar for a dropper seatpost lever.How Di2 XTR Stood the Test of Time
Shimano’s Di2 XTR earns the high marks for reliability and durability – and after a full season of thrashing, all indications say that Di2 will hold up better than mechanical XTR. Check out Mike Levy's review of Shimano's M9000 mechanical XTR
for the full story. Wear on the cassette cogs was slightly less on the larger and smaller sprockets and about the same in the middle ones – which stands to reason, because the computer manages the two derailleurs to keep the chain in the middle of the cassette, which eliminates the most offending cross-chain combinations. Good thing, because new XTR chainrings are P R I C E Y items to replace.
The derailleurs cranked out shifts without fail and with no need for an adjustment for the first three months of testing. After bashing against some hefty boulders, however, the rear changer needed a slight adjustment. Di2 derailleurs are adjusted using the small display. After selecting the adjustment mode, tapping one paddle will move the changer left, while the other moves it right. One adjustment in an entire season of riding was pretty hard to believe.
The front changer was equally reliable. Its motor is massively powerful and can force the chain up to the larger chainring under full climbing torque - and that is how I used it. I never let off the gas to make its job easier in either direction and, except for one rather embarrassing moment, it never tossed a chain, left me to deal with a grinding noise, nor missed a shift, The big moment came immediately after I loudly proclaimed during a popular group ride that I had never tossed a chain - then, boom! It shifted the chain off the small ring and into neutral. I swallowed my pride, made a tiny adjustment to the inside stop and never had another issue.
Water and mud did not adversely affect either changer, nor was there any lapse in service that may have been caused by a leaky fitting. Shimano must have a Di2 test submarine in their research and development wing. I did have some issues with the tape that is used to conceal the wires where they pass under the handlebar. Once dust sneaks under the adhesive, it starts to look natty. The tape did remain in place, so functionally, it was a win for Shimano. I purposely photographed the components unwashed and beaten by the elements, but the changers did clean up well.
|Battery life was so good (Shimano insiders say 20 hours of race-shifting between charges) that I actually forgot that I had to charge it the first time and nearly ran it down to nothing.|
Battery life was so good (Shimano insiders say 20 hours of race-shifting between charges) that I actually forgot that I had to charge it the first time and nearly ran it down to nothing. There is a USB port in the display that hooks up to the Di2 charger, so there is no need to remove the battery. I charged the system twice in five months and the indicator said I had a third of a charge left when I sent the bike back.
Noisy cassette cog:
E-Tube program: Good marks to Shimano for making its programming software easy to learn and intuitive to manage. Sadly, it is still PC only. A smart phone app would also be great.
To beep or not to beep: When I first started in with Di2 XTR, I hated the warning beeps that sound when you have reached the last cog of the cassette and also before the system executes a double shift (both derailleurs simultaneously). I used the E-Tube program to eliminate the warning sounds, but after a month, I wanted them back. Turns out, it's nice to know that information.
Not something that I was expecting from Shimano, the chain seems to struggle slightly when pedaling hard in the large chainring and the second largest cog. There seems to be some noticeable drag in that option as well.Syncro shift modes:
Shimano nailed it. Don't bother trying to outfox the computer and don't bother with a left-side shift lever. Depend upon either of the two default Synchro options to select the proper gear sequences and forgettaboutit.Pinkbike's Take:
|There is a reason that top sports car makers have abandoned the stick shift and adopted electronically assisted dual-clutch transmissions and paddle shifters. They shift faster and more accurately and, more importantly, paddle shifting removes much of the workload from the driver. The same can be said for Shimano's Di2 XTR. If money were no object, only nostalgia would be a reason to choose mechanical shifting on a mountain bike - or a stick shift on a road car. |
Is Di2 for everyone? Certainly not for the budget minded. Bike makers could offer a substantial suspension or chassis upgrade for the additional expense of Di2 XTR, but at the price point that Di2-equipped bikes will be offered, it would be as difficult to defend the retail cost of any other component. The bottom line is that Shimano's take on electric shifting will make you a better rider, and that is true whether you are a top pro or a rank amateur. No. You don't need it. Yes. You will want it. Look no further than SRAM for verification - their electric mountain bike group should debut this spring. - RC
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