When SRAM began offering Rival, its third-tier groupset, with eTap AXS wireless shifting last year it seemed only a matter of time before Shimano would follow suit and bring Di2 to its much-loved ‘workhorse' groupset, 105. Well, that time is now.
Although it was expected, the arrival of Shimano 105 Di2 is no less significant. Like SRAM Rival AXS (opens in new tab), which we reviewed very favourably, it brings electronic shifting to a wider audience, or as Shimano says in a “more attainable package.”
For several years, and through a number of iterations, 105 has arguably been Shimano’s most popular groupset. Sitting below Dura-Ace (opens in new tab) and Ultegra (opens in new tab)in the pecking order, it’s routinely punched above its weight, or price to be more accurate, with the benefits of trickle-down technology making its functionality as well as its aesthetics barely discernible from its more expensive brethren.
Despite 105 Di2 at £1,730/$1,886.87 costing around twice as much as the older 11-speed mechanical version - but still considerably less than Ultegra Di2 (almost £700/$850 cheaper) - Shimano will be relying on the new groupset to deliver the same.
To do so, it says that, once again, it’s bringing the “function and technology inherited from recent ground-breaking updates to Dura-Ace and Ultegra” to the 105 Di2 platform. The most significant of those advancements is semi-wireless shifting and 12-speed gearing, and both feature here.
The new R7100 groupset uses what Shimano describes as a “hybrid system”, which blends a wireless cockpit (with coin cell batteries in the hoods) with a wired connection between a battery and the derailleurs, with this central battery ‘hidden’ in the seatpost. The exact same system used by Dura-Ace and Ultegra, Shimano says this delivers both faster shift speeds and a longer battery life.
Shifting can then be customised using the E-Tube Project app, allowing you to adjust the shift speed, choose from Synchronized or Semi-Synchro shifting and alter the number of shifts per button press amongst other things.
A move to 12-speed naturally increases the gear range. Shimano is offering 105 Di2 with a couple of Hollowtech II chainset options, 50/34 and 52/36, like Ultegra, though the latter won’t be available until a “later date”. Paired with either an 11-34 or an 11-36 cassette it provides at least a 1:1 low gear for the steeper climbs. Ultegra's widest range is 11-34.
As with all 12-speed drivetrains the extra cog means smaller jumps between gears, which should make finding the right cadence easier. Shimano has also been good enough to make the new cassettes ‘backwards’ compatible with its 11-speed freehubs, as with Dura-Ace and Ultegra 12 speed.
So what else is new? The 105 levers have been overhauled, with the hood raised and the levers reshaped with the goal of improving ergonomics in the pursuit of better control and comfort. As with the revamped Ultegra R8100 levers, access to the buttons has been improved too. When it comes to braking Shimano is claiming a “lighter, smoother” action as well as a hydraulic system that’s easier to bleed, with no need to remove the caliper from the frame. Pad clearance has also been increased by 10%, which should mean less rubbing.
First ever carbon 105 wheelsets
There’s also two accompanying RS710 carbon tubeless-ready wheelsets, with the C32 designed for climbing and the C46 aimed at all around use. As you might have guessed the numbers relate to the rim depth, with both featuring a 21mm internal width, no doubt designed to work well with today’s higher volume road tyres. It's also worth noting that these are the first 105-level wheels to use carbon rims.
Weight difference v Ultegra and Dura-Ace
While trickle-down tech can make the functionality of second or even third-tier groupsets indistinguishable from the flagship models, this generally comes at some level of weight penalty.
For Shimano 105 Di2, the claimed weight of 2,995g (with the 11-34 cassette and compact chainset) puts it at 279g more than Ultegra R8100. This represents a widening of the gap between the tiers, with the difference previously being 191g between the 11-speed mechanical iterations.
However, if the difference in weight is a little greater, the difference in price is significantly so. The latest iterations of 105 and Ultegra are now separated by £1,369, when previously the gap was just around £400 / $400.
The release of 105 Di2 continues the democratisation of electronic groupsets. As with SRAM’s Rival AXS it brings the technology within reach of many more cyclists, both as groupset upgrades and through its availability on more keenly priced complete bikes. But what does it mean for Shimano’s mechanical groupsets?
Unlike SRAM, who seem to have gone all-in on electronic gruppos highlighted by the lack of recent upgrades to its mechanical offerings, Shimano is continuing to balance the two. It still offers Ultegra in an 11-speed mechanical option and fans of the traditional 105 groupset will be pleased to hear that this is also the case for 105, with Shimano confirming that it will remain in production and with no word as to when it will be discontinued.
What does this all mean for 105?
Ever since the launch of 12-speed Dura-Ace and Ultegra last year, the questions started swirling about Shimano 105. Would it stick with mechanical shifting but add a sprocket – like Shimano’s mtb groupsets? Or would the gearing stay the same and just an electronic option be added – like the previous iterations of Dura-Ace and Ultegra?
Well, we might now have those answers – another sprocket has been added and mechanical shifting has been entirely replaced by electronic – but it’s raised a whole load more. I’ll pick just two to consider here: Has Shimano just cannibalised GRX Di2 (opens in new tab)? And is the development of mechanical groupsets now dead?
Starting with the first, there are actually quite a lot of features of R7100 105 which do make it compelling as a gravel groupset – especially given that the retail price is around the same as GRX Di2.
First is the brake pad clearance to the rotors. That extra 10 per cent was welcome enough for the (generally) cleaner conditions of the road – it’s a development that’s arguably even more important for the muck, grime and debris that’s part and parcel of gravel riding.
Second is the gearing. New to 12-speed 105 is an 11-36t cassette option, which offers a little more range than the current widest spread of 11-34 that’s available for Shimano GRX Di2. Now, we don’t have the actual gearing progression just yet, but given that the 11-34 12-speed cassette has the same number of single tooth jumps as an 11-28 11-speed cassette - we’d hazard a guess that R7100 105 will have smaller jumps than GRX as well as a wider range.
It is true that the stock crankset options for 12-speed 105 don’t accommodate the lower gearing needed for gravel. But although Shimano might not approve, there are always third-party options for getting what you need.
But perhaps it’s worth a little caution. GRX itself hasn’t had an update since its launch back in 2019, so an update is likely on the cards – if not later this year then perhaps next. So it would probably be best to hold on for that. But if you are in a pinch for electronic gravel gearing from Shimano before then (what a situation to be in), then 105 might well be the better option.
Onto the question of mechanical groupsets. Generally we’re used to product lines getting continually updated and improved. Mechanical 11-speed 105 was an excellent blend of great performance and reasonable price and, although it will continue to be sold, it does feel odd that we could have hit the high point in 2018 and that be the best it’s going to be.
But perhaps things are more promising than that. Currently Tiagra is now looking a bit of a poor relation, stuck with 10-speeds while the big three have moved on to 12. A trickle down of an extra sprocket looks as though it should be firmly on the cards – and would likely bring 11 speed gearing to an even lower price point.
So nice while it is that 12-speed 105 Di2 does save so much over Ultegra, perhaps the most significant upshot is the implication of what could be next for Tiagra - and just how good Shimano’s fourth tier could become.
Shimano 105 R7100 Di2 prices
105 Di2 hydraulic disc STI shifters and flat mount caliper set front: £349.99 / US$404.99
105 Di2 hydraulic disc STI shifters and flat mount caliper set rear: £349.99 / US$404.99
105 12-speed 50/34 chainset: £169.99 / US$179.99
105 Di2 Front derailleur: £149.99 / US$152.99
105 Di2 Rear derailleur: £274.99 / US$279.99
105 12-speed cassette 11/34 and 11/36: £69.99 and £84.99 / US$65.99 and $87.99
Groupset price inc. rotors, chain, Etube wires and battery: £1,730 / $1,886.86
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Luke Friend has worked as a writer, editor and copywriter for over twenty years. Across books, magazines and websites, he's covered a broad range of topics for a range of clients including Major League Baseball, the National Trust and the NHS. He has an MA in Professional Writing from Falmouth University and is a qualified bicycle mechanic. He fell in love with cycling at an early age, partly due to watching the Tour de France on TV. He's a passionate follower of bike racing to this day as well an avid road and gravel rider.
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