We’ve finally got our hands on Shimano’s latest 105 Di2 R7100 groupset and weighed all the shiny bits and pieces

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Shimano’s new 105 Di2 groupset adds a long-anticipated third tier to the brand’s electronic shifting. Sitting below Dura-Ace R9200 and Ultegra R8100, it shares a lot of tech with those two groupsets, just with slightly fewer flashy materials and increased weight.

It’s that weight we’re going to focus on here – Shimano supplied claimed weights for all the components when Shimano 105 Di2 12-speed was launched back in June 2022. Now we’ve got a complete groupset in for review and we’ve started off by putting everything on the scales to find out how much each component actually weighs

Here’s a run-down of key features that Shimano 105 Di2 has to offer. 

First up, it’s semi-wireless with a non-wired connection between the shifters and the rear derailleur driving shifting.

The shifters lose some functionality seen on Ultegra and Dura-Ace, such as a third button and the option to add satellite shifters.

In compensation, 105 Di2 levers have space for two coin cells rather than one, doubling battery life. 

There are 50/34t or 52/36t chainset options with a wide range of crank lengths, but there’s no power meter.

That’s paired with cassettes offering 11-34t or 11-36t range, although without the faster-shifting and smoother Hyperglide+ technology of Ultegra and Dura-Ace.

Like those groupsets, 105 Di2 uses brake rotors and chain borrowed from Shimano’s mountain bike groupsets – in this case SLX.

The new 105 Di2 groupset doesn’t offer rim brakes and its disc brakes don’t have the Servowave tech of its more expensive siblings, but as with them, the brake pads retract 10 per cent further, so you should get less brake rub.

The new 105 shifters look almost identical in shape and size to Ultegra and Dura-Ace. They are larger than Shimano’s older 11-speed electronic shifters from those groupsets.

As with Ultegra and Dura-Ace, the brake lever pivot has been moved to ofer better leverage from the hoods, which cover more of the lever mechanism.

Unlike Shimano’s higher-spec shifters, there’s no ‘hidden’ third button, so you can’t programme it to handle screen changes on a bike computer or other functions.

You can’t fit satellite shifters either, because there’s no port. In return, the saved space in the lever body is used to provide each shifter with two coin cells rather than one, which Shimano says increases battery life to as long as four years.

Shimano has a claimed weight of around 20g less than our measured weight – quite possibly because our shifters had brake fluid in them.

At launch, the new 105 crankset was available in 50/34t configuration only. Shimano will also offer a 52/36t option at an unspecified date.

There are 160mm, 165mm, 170mm, 172.5mm and 175mm crank arm lengths. You can also use Shimano 105 with a non-series 12-speed 50/34t chainset designated RS520.

The crankset is one component where there’s plenty of room to massage weights down: the shortest crank length should deliver useful weight savings. So Shimano should be commended for quoting the weight using 172.5mm cranks, the most common size. Its number is pretty much spot on our figure.

Designed for braze-on derailleur hangers, the 105 front derailleur can handle 50t or 52t large chainrings, with a 16-tooth maximum capacity.

Like Shimano’s other Di2 front derailleurs, it’s self-trimming to avoid chain rub as you traverse the cassette. The motor housing is a bit larger than Dura-Ace or Ultegra and more in line with Shimano’s older 11-speed derailleurs.

Our front derailleur weighed a few grams less than the quoted weight.

The rear derailleur is the brains of the outfit, housing the charging port and Di2 connection. It provides wireless connectivity to the shifters, battery and system status indicator lights, adjustment switches, Bluetooth and ANT+ connectivity to cycling computers and Bluetooth connectivity to smartphones to run the Shimano e-Tube app for system configuration.

There’s one model with a long derailleur cage for compatibility with cassettes up to 36 teeth.

Our 301g measured weight was pretty much spot on the quoted weight.

There is currently only one in-series 105 12-speed cassette. Unlike Ultegra and Dura-Ace, this doesn’t get Hyperglide+ tech, which is designed to speed up shifting and make it quieter. You can also purchase a compatible 11-36t non-series cassette if you want a sub-1:1 gear to conquer steeps.

Our real-world weight of 360g is on the nail with Shimano’s claimed weight.

The chain used by 105 Di2 is a component that’s been ported over from the Shimano SLX mountain bike groupset.

Again, our weight is pretty much spot on Shimano’s claimed weight.

105 Di2 uses the same 3.7Wh, 7.4-volt DN300 battery as Dura-Ace and Ultegra to power the front and rear derailleurs. There’s a third port for wired connections to shifters from the higher-tier groupsets, although that’s not an option with 105.

It’s another weight figure that’s dead on.

There’s not much to say about the cables – you need them to connect your derailleurs to the central battery and they don’t weigh much. In fact, they’re thinner than the old 11-speed wires (we don’t know how much weight you save there).

Shimano’s claimed weight for the electrical cables to connect the central battery to the derailleurs is pretty much spot-on. In any case, there’s not much to be gained or lost here and any discrepancy is likely down to things like cable ties.

Shimano’s new 105 disc brake calipers have a bleed port on the outer side, for easier access. As with Ultegra and Dura-Ace calipers, the pads retract 10 per cent more than the previous-generation brakes, so there’s less chance of that annoying brake rub or clicking.

We weighed the rear caliper and hose at 166g, which we’ve doubled up to 333g. The actual weight of a pair of calipers would be a bit less than this though, because the front brake hose is shorter. Shimano claims 141g per caliper, so 282g per pair.

Our weight for the brake calipers and hoses is over 50g more than Shimano’s quoted weight for the caliper alone. An extra 50g for the hoses is probably about right.

As with its higher-spec 12-speed groupsets, Shimano hasn’t looked to reinvent the wheel with its disc brake rotors, instead repurposing the rotors from its SLX mountain bike groupset, which are also used with 11-speed mechanical 105.

These have a steel-aluminium-steel sandwich and are labelled Freeza for the design’s ability to reduce heat build-up in the braking system.

We weighed the rotors at 33g less than Shimano’s quoted weight, possibly because Shimano has quoted the weight for a pair of 160mm rotors, whereas one of ours is a 140mm diameter.

Summing everything up, our total groupset weight is 42g less than Shimano’s quoted weight for the 105 Di2 groupset in its launch materials, a 1.5 per cent difference. We don’t have a bottom bracket in our mix though.

The 105 Di2 bottom brackets are shared with Ultegra, with the Pressfit bearing weighing a claimed 69g and the threaded option 77g. There are other bits such as rotor lockrings we don’t include.

Bike makers have a tendency to massage weights and quote figures, for example, for unpainted frames without bearings, so it’s nice that Shimano has given us weight claims that stack up in the real world.

Compared to Shimano’s more expensive groupsets, our total for 105 Di2 is 373g more than our measured weight of 2,577g for 12-speed Ultegra Di2 and 511g heavier than Shimano’s claimed 2,439g for Dura-Ace Di2.

Not bad, considering you’re saving around £2,000 on the price of Dura-Ace. The weight of 105 Di2 also comfortably undercuts SRAM’s competing Rival groupset, which we calculated at around 3,100g.

The last part of the 105 Di2 jigsaw is the brand’s new carbon wheelsets. There are 32mm and 46mm-deep sections with the same rim profile as the latest Ultegra and Dura-Ace wheels.

The 32mm-depth wheelset has a claimed weight of 1,504g; the 46mm wheelset is 1,607g. We’re looking to get our hands on them for review too.

But next up is to fit the 105 Di2 groupset to a bike and head out to test it, so watch out for a full review.

Paul has been riding since he was a teenager and has been writing about bike tech for almost a decade. He was into gravel before it was even invented, riding a cyclocross bike across the South Downs and along muddy paths through the Chilterns. He dabbled in cross-country mountain biking too, before returning to drop bar bikes.

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