Shimano Dura Ace Di2 groupset

Di2 is Shimano's new, flagship groupset. Combining Dura Ace 7900 ergonomics with the performance of an electronic shifting mechanism sets this apart. Di2 is the best groupset that I have ever ridden, but then for this money so it should be.

Enhanced shifting performance is the most obvious benefit of Shimano’s Di2, the sheer speed and accuracy of the gear changes is awesome - electronics aside the mechanics are the same as Dura Ace 7900, but what the electronic side of Di2 does is to take away the capacity for pilot error, you can still change gear at the wrong time of course, but when you do it will be a precise and accurate shift with neither too much or too little power behind it and with the chainline already in the optimum position.

It hits its target each time, every time, and nails each gear without fail in any condition (I have had it out in thunderstorms, mud, heat etc). I wondered if I would be able to tell what all the fuss was about in comparison to the wired Dura Ace 7900. I can: the performance of Di2 is staggering.

Shifting is impeccable and fast, when returning the test rig Dave asked if I had struggled with the inability to ‘double’ shift as on my normal group sets. The answer is a resounding no, the speed that Di2 changes is nuts, you can change 2 gears on Di2 in the same time as a double shift on a standard lever, furthermore you don’t need to stretch out your fingers to do so, two light taps will suffice. The up-shift at the back gives the reliable and reassuring clunk of a spot on shift however downshifting is all but silent which on occasion led me to tap the shifter twice quickly only to realise too late that it had in fact changed as I was making my second move.

The group set on the test bike (A Cervelo S3 with full Di2 with Dura Ace 7850 deep carbon rims) was a no expense spared affair and this resulted in a truly sublime performance. The most impressive component of the Di2 package for me is the front shifter and the up-shift in particular. It was effortless and 100% accurate. An audible whirring accompanies the shift as the motor in the front derailleur silkily moves the chain across, working perfectly when hammering down an A-road or accelerating over the crest of a hill not once was there any chain rub, hint of over/under shift or lack of trust on my part.

As you've probably guessed by now I liked Di2: the overall performance of Di2 was superb, more so than I expected and the difference in performance over anything I’ve ridden before (Shimano, Campagnolo or SRAM) was clear from the first mile. Shimano claim a mere 50g weight increase for Di2 over Dura Ace, 50g for effortless shifting, battery power, automatically adjusted derailleur position... if i had the cash, I wouldn’t think twice.

Even when I went mad to try and confuse the system by shifting up four or five times rapidly while downshifting at the front and then up and down shifting at the back – it always corrected itself. You would never do this on a top end mechanical group set so it’s not really a fair test but the system coped with it easily. As mentioned previously I rode the bike in all manner of conditions, the question of an electric shifting set up working in the most torrential rain was answered emphatically, it was far more at home in the wet than I was. During one particular ride the roads were flooded, the fields were draining onto the roads so a combination of mud, gravel and water was dousing the battery, the ‘brain’ of Di2 which hangs in front of the stem on the wires and the derailleurs. No problems at all, the shifting performance remained superb and reliable; this was fast looking like a case of you get what you pay for. Di2 is a lot of money but wow you get a lot of performance for it.

So why does Di2 work so well, why are the shifts so smooth and why is the overall gearing system so sharp? Well the small motors in each of the derailleurs play a big part, these control, together with the 'brain' control the motion of the components precisely. The units don’t actually move the derailleurs that quickly, they are, in fact, slower than the mechanical equivalent but they are so accurate because they are constantly adjusted by the previously mentioned ’brain’ to run in the most efficient way. These adjustments and the way that the shifts occur aren’t possible on a mechanical set up, especially not while in motion that's what really does set Di2 apart.

When I say that Di2 actually shifts the chain slower than a mechanical equivalent this is purely the speed at which it moves the chain - everything else about it though combines to make the overall shifting experience faster.

Controls

Ergonomically the levers work too, with no need for the workings to pull cables to be hidden inside the lever bodies and hoods (the reason Di2 is only 50g heavier than 7900) the Shimano engineers could concentrate on making them a comfortable shape. They are slimmer and slightly narrower than the 7900 levers and with smoothed contours they fit very nicely into your hand which inevitably means more comfort and pleasure on longer rides. I ride on the hoods quite a bit so the layout of the buttons was ideal for me with them being positioned where I would instinctively reach for a lever movement, riders who use drops more may find the button placement needs a little more time to get used to however. I would expect it to be one of those things that riders can adapt to, given a ride or two this may well become second nature and the speed and accuracy with which the system works means even riders who use drops shouldn’t be put off.

Remember this testing has been carried out in hot, cold, wet and dry conditions however; riding this beast in the winter could be trickier than I may be suggesting. The buttons don’t feel that different and they don’t move much, it’s more a case of relying on feeling the gear change rather than knowing it has happened like you would with traditional spring derailleurs. If I were riding this to my workplace in January, in minus 3 temperatures wearing full winter kit with thermal long fingered gloves then I expect that a fair few shifts would go awry, not because the system would fail but because I wouldn’t be able to tell clearly which button I was tapping!

Having heard of and seen images of the time trial shifters and the ability to mount buttons elsewhere on the bike (such as on the top of handlebars for climbing scenarios) I think that Di2 is spread across the board well enough to tempt a variety of markets and perhaps the TT shifters make even more sense than these standard drop shifters as used on test. Being able to keep the shifters in one aerodynamic position while maintaining the full use of a gearing system’s range must be an advantage when riding against the clock

Battery life, fitting… repair

The first question I asked when told I would be testing this set up was “how long does the battery last?” Albert from Madison (Shimano’s UK distributor) has sent me through a bundle of pdf’s and data that claims the battery pack would last on average about 1600km worth of riding before a recharge and that in its full lifetime the battery would most likely outlive anyone who rides with it (500 recharges x 1600km of riding....) so no immediate worries there! Clipped onto the wiring up front is a very small, neat little box of tricks that houses the warning LEDs and other gubbins for the system. The led will blink as the battery is running out of juice so you have a good level of pre warning. If the worst does happen then you can be out on the road again in little over an hour as the battery takes just this long to go from empty to fully charged. As I have talked about before, electricity and water don’t mix so despite being encased in hardwearing shells the battery pack and derailleur’s need to be able to cope with a good old British deluge, they do fine, no slipping, no grinding, nothing to suggest the kit isn’t up to the job.

As far as fitting the kit yourself, feel free but make sure you get it right – as with Dura Ace 7900 initial set-up has to be accurate. Personally I would get a top notch Shimano trained mechanic to do the work for you. That said, I wheeled the bike into several bike shops in Bristol, some names you will know, others independents and I got varying levels of response from “ooh that’s pretty” to “ah, umm, I wouldn’t like to try that one yet”. Madison say around 20 mechanics have taken the option of their free Di2 specific training, additional instructions and details are available on their business websites. As Albert said “Di2 is really not as complicated as it may first appear. Initial installation is important to get right but after that the system is pretty much idiot proof and requires only the slightest of adjustment should the rear mech/hanger get knocked.”

Internal routing was working well on the Cervelo test rig, giving the whole system a neat, smooth, clean look. Something that makes you feel fast! Perhaps it was a sensible idea for Shimano to supply us with a black and silver Cervelo frame to test Di2 with as the fittings and fitments are black and therefore are barely noticeable, even the cable tied sections on the battery (which does seem a little cheap for this sort of set up) were hardly visible. The battery pack also has a clip to help attain a secure fit; approximately 6 inches long it reaches along the down tube and fits beneath a bottle cage and then gets clamped securely in place when the bottle cage is screwed in tight, a smart use of pre-existing design.

If you are unfortunate enough to crash while using Di2 Shimano have built in a couple of features that they claim will limit the damage. Essentially the rear derailleur can come apart into two sections when impacted so the motors and workings are protected while the body can break away. No word from Shimano about the possibility or the cost of replacing a damaged section here. This is where my main worry lies though, with such a technological, exciting and therefore expensive system, how much is overcooking it in that corner or coming into contact with a pre-occupied driver going to cost? Di2 is a major investment. A rear derailleur is £489.99, the front £369.99, the shifters, £499.99 for a pair, the required wiring harness, battery and charger bump this up a further £344.95 so all in all it will set you back the princely sum of over £1700 (without a cassette, brakes, chain set etc).

The Di2 kit is designed with the intention of the consumer filling in the gaps with equally bling DA 7900 componentry, this is how the test bike arrived and I must say I can’t fault the results – of course filling in the gaps is going to bump up that £1700 considerably.

Doing the sums on cost inevitably leads me to wonder who Shimano are targeting with this level of kit. Team Garmin Slipstream rider Brad Wiggins rode it throughout the Tour this year with great success but he won’t be paying for it, so where is the market? Those who simply need the best and can afford it I suppose, the rest of us want it but can’t justify the cost. If you are a top level rider who earns from the sport then this could be for you but for club riders it may well be a luxury too far.

Mind you, as soon as Shimano bring the Di2 prices to a more earthly and palatable Ultegra level. I will be the first in the queue if this series is anything to go by; it's a fantastic system that accepting a couple of ergonomic issues that bias toward hood riders like myself is spot on.

Verdict

Shimano Di2 7970 is superb I can find no faults with the way it works. For the money it should be good and it is. If you need the best on your bike then go and buy this, it is fantastic.