How does the Shimano Ultegra Di2 6870 digital groupset stand up to a season’s racing, training and sportive riding? Henry Catchpole reports

Product Overview

Overall rating:

Score 10


  • Looks great
  • Well priced
  • Great battery life
  • Pretty much maintenance free


  • Gear change buttons close together


Shimano Ultegra Di2 6870 groupset


Price as reviewed:


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New & Used from eBay


Despite lots of glowing reviews from the launch, it was with a healthy dose of uncertainty that me and my Luddite leanings approached a six-month test of the latest Shimano Ultegra Di2 6870 groupset.

I’ve had brief flirtations in the past with the old 6770 Ultegra Di2 and the first thing that I noted about the new groupset before I’d even pedalled a yard is how much cleaner and less bulky it looks. Things like the slimmer rear derailleur and the ability to hide the battery inside the frame are much more attractive.

Similarly, the way the new junction box (where you also plug in the charger) is secured neatly under the stem by a heavily engineered elastic band is much more appealing than the old box that used to dangle down untidily in front of the stem.

These things are important because you don’t want a beautiful set of tubes spoiled with ugly appendages. It’s the equivalent of constructing a carbuncle of a conservatory on the side of Anne Hathaway’s cottage or planting a wing on a Porsche 356 Speedster.

In terms of actual shift quality the groupset is beyond reproach to my mind. I tried extremely hard to pick holes in it, I really did. At one point I lay awake at night wondering if there could be quite the speed and snap to changes down the rear cassette when really sprinting — could the motor whirr and respond as quickly as a spring releasing tension?

I tried it in a full-on bar-heaving dash for an imaginary line the next day and the shifts were not only blindingly quick but also smooth. The switch between front rings was even more impressive, never baulking, never stumbling once in six months.

This knowledge that the change will always go home is perhaps the thing that I was most intrigued about. Some of you may know that in my other job I test cars for a living. For a sports car I would nearly always choose a manual gearbox over a paddle shift or automatic, simply for the extra interaction and enjoyment of changing gear myself.

Similarly there is some pride in finessing the pedals and judging the throw of a lever when changing with a mechanical groupset, but did 
I miss it with Di2? Honestly, I don’t think I did.

What I did occasionally long for was greater distinction between the two shift buttons, because despite being textured differently they’re very close together, and, particularly with a set of gloves on or over rough ground, it was sometimes less than instinctive to land your finger on the required one. Similarly, the positivity of the buttons could still be improved so that you have a more positive feel and reassuring ‘click’ to let you know you’ve triggered the switch.

Having said that, I raced on the bike a couple of times early in the season and I’m sure that in general the lack of thought you have to put into shifts with Di2 is a boon when you’re tired or concentrating madly on the maelstrom of a constantly morphing peloton. Likewise when you’re knackered and pedalling squares at the end of a long training ride, even the slightest reduction in movement and effort to swap cogs is sometimes welcome.

Speaking of reduced effort, I’m not a huge fan of full compacts, but the semi-compact 52/36 set-up on the test bike was perfect for almost everything that I found myself doing. Racing was really the only time that I wanted an extra tooth on the big ring and even then I was glad to have a ready-made excuse for struggling to hold onto the E/1/2s at the MK Bowl on a Thursday evening.

Leaving the gears aside for a moment, there are two other areas of the Ultegra 6800 series that are well worth mentioning. First the brakes are superb, being full of power and yet also being easy to modulate. Then there are the 
SPD-SL pedals. Normally because of time constraints I swap my trusty Look Keos onto a test bike, but as this bike was with me for rather longer than normal it gave me the chance to set up a pair of shoes with Shimano cleats and use the carbon Ultegra pedals.

At first they felt slightly tricky to engage, because the front portion of the cleat has to drop down through the hole in the pedal rather than being caught by a lip, but you do get used to this and once located there was a fantastic sense of security, stiffness and also stability across the broad main contact patch. I also like that wear on the cleat from walking seems to have less of an effect on performance than with Keos.

For more on this and other Shimano groupsets, see


Overall it’s fair to say that I was very much won over by Shimano Ultegra Di2 6870 during my time with it. Mechanical groupsets clearly still have their place, but I’m now convinced that electronic shifting has some clear advantages as well. If nothing else then the complete lack of maintenance 
and adjustment that Di2 required (I charged the battery just twice) was a complete joy. The sheer quality of the whole package was also remarkable and with only 300g difference I think you’d need a seriously good reason to justify spending twice the price on 9070 Dura Ace.

Full Specification
Rear derailleur Ultegra Di2 6870:From £174.99

Front derailleur Ultegra Di2 6870:£169.99
STI gear shifters Ultegra Di2 6870:from £249.99

Brake calipers pair Ultegra 6800:£109.98
Chainset Ultegra 6800:£199.99

Bottom bracket BB-R60:£21.99
Chain Ultegra 6800:£27.99

Cassette Ultegra 6800:from £59.99
SPD SL pedals Ultegra 6800:£109.99

E-tube Di2 bottom bracket Junction:£19.99
E-tube Di2 Junction-A:from £69.99

E-tube Di2 electric wire, from 300mm:£17.99
E-tube SEIS battery – internal:£129.99

Battery charger:£64.99

  • aradilon

    Tony Martin did a Tour de France with 1 charge and that’s because he wanted to be sure to not run out. That’s what i’ve heard from a mechanic!

  • Peter Cain

    About 3 months and you get plenty of warning before the battery completely runs out. Mine has needed charging once and took about 2 hours to charge back up.

  • Bo Treat

    but how long does one battery charge last? it’d have to be over 24 hours of riding, for me to even consider something that takes energy to use, because you don’t always have the opportunity to charge.

  • Unfiltered Dregs

    Go down a mountain on r785 and then report back on the no difference versus rim brakes….lol