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New Shimano 105 R7100: The group goes electric

The mid-tier set is looking a lot like its top-end siblings with Di2 and 12-speed cassettes

Shimano 105 R7100

You know how siblings look alike? The whole sharing a lot of the same DNA thing. Well, the new Shimano 105 R7100 is now looking a lot like Dura-Ace and Ultegra, which were revamped for August 2021. Group No. 3, that’s 105, now shares many features with the No. 1 (Dura-Ace) and 2 (Ultegra) road component sets.

RELATED Weights and Canadian pricing for the Shimano 105 R7100 group

If you are keen on the latest tech making its way to a lower price point, you’re going to dig the new 105 group. If you are a traditionalist who likes brakes with rubber pads and derailleurs with wires (the kind that aren’t used for conducting electricity), well, you’re not going to like what you’re about to see. But, really, you kinda knew this was coming.

Shimano 105 R7100
The Shimano 105 R7100 rear derailleur not only has shifting duties, but it’s the hub of the wireless shifting activity as well as place where you charge the main Di2 battery.
Shimano 105 R7100
Shimano 105 R7100 front derailleur

Power up! Like that, 105 has batteries

Just like Dura-Ace and Ultegra, the derailleurs of the 105 R7100 group are powered by a battery stored in the bike’s seat tube. In fact, it’s the same battery, DN300, that the other sets use. The front and rear mechs are wired directly into the main battery. Under each brake hood, there are two CR1632 coin-cell batteries. (That’s double the number of batteries compared with Dura-Ace.) These cells power the transmission of wireless signals to the derailleurs with their servomotors that help them to push and pull the chain across cogs and chainrings. The rear derailleur is a pretty busy part. It houses Shimano’s D-Fly componentry, which lets you connect the Di2 shifting system to your smartphone or cycling computer. It’s super handy to be able to monitor battery life from your Garmin. You can customize and tune the shifting via Shimano E-Tube Project app.

Shimano 105 R7100
Two batteries under the hood. Shimano 105 R7100.

Two things 105 has that Dura-Ace and Ultegra don’t

You don’t have to dig out your phone or your head unit to check the remaining juice in the batteries housed in the levers. Each lever has an indicator light that goes green if you have more than an 11 per cent charge. If you have 1 go 10 per cent, the light is red. No light? The coin-cell batteries are really dead.

Like Dura-Ace and Ultegra, 105 has an 11-34 tooth 12-speed cassette. But the new set also has an 11-36 tooth, which the other guys don’t. The new derailleur will work with both cassettes. Paired with the 50/34-tooth crankset, the 11-36 cassette gives you a highly spinnable range for getting up even the steepest inclines. Later, Shimano will release a 52-36-tooth crankset for those riders who want more gear inches.

Shimano 105 R7100
The Shimano 105 R7100 50/34 crankset.
Shimano 105 R7100 11-34 tooth cassette.

But, you’re telling me the new Shimano 105 R7100 doesn’t have…

The new Shimano 105 R7100 doesn’t have a mechanical shifting option. It’s Di2 only. Also, no rim brakes. Hydraulic disc brakes stop your wheels.

Better brakes

The 105 R7100 calipers have 10 per cent more clearance between the rotors and the brake pads. That should keep rotor rub at bay. Shimano says the braking behaviour of 105 is much like that of Dura-Ace and Ultegra: quick initial contact with a good zone of modulation. Each brake lever has about 16.4 mm of reach adjustment available.

Shimano 105 R7100
Shimano 105 R7100 caliper
Shimano 105 R7100 caliper clearance

Do I need new wheels?

You don’t need new wheels to run the 12-speed 105 cassettes. They will work on 11-speed freehubs.

RS710 C46
The RS710 C46 rim has a depth of 46 mm and an inner rim width of 21 mm.
Shimano RS710 C32
The Shimano RS710 C32 rear wheel is 839 g.

But if you do want new wheels…

Along with the new drivetrain and brake components, Shimano is releasing two sets of wheels. While the new hoops complement the 105 parts, the wheels are technically non-series. The RS710 carbon wheels draw from the C36 and C50 Dura-Ace and Ultegra options. The RS710 wheel designed for climbing, the C32, has a lower rim depth (32 mm) than its top-end siblings. They all, however, have the same internal rim width: 21 mm. The C32’s front wheel is 665 g, while the rear is 839 g. For more of an aerodynamic advantage, there’s the C46. It’s front wheel is 719 g and its rear is 893 g. All wheels are tubeless-ready.

New road rotors CL900 and CL800

In the mix of the new 105 parts and the new wheels are two rotor designs that Shimano says will give you better braking performance. The CL900 and CL800 come in 140- and 160-mm diameter options. They use a familiar Shimano technology: Ice Technologies Freeza. It’s a sandwich made with a central aluminum piece (the meat, if you will) between layers of stainless steel (the bread). This setup helps to dissipate heat. The company says these new rotors have 140 C of overall heat reduction and will last 10 per cent longer than stainless-steel rotors.
The carrier portion of the rotors is aluminum. On each disc, this section has been redesigned to reduce heat deformation. The CL900, the more premium rotor, has heat-dissipating paint on it.

All this technology aimed at reducing heat also means the rotors retain their shapes and structures better during operation: think long, steep descents. With less deformation, the rotors perform better and are quieter.

Shimano RT-CL900 rotor
Shimano RT-CL900 rotor, 140-mm diameter, with heat-dissipating paint

So how much, and how heavy, and when can you get it?

The new 105 will start appearing on new bikes in about two months or so. The “or so” is due to continuing supply-chain challenges. If you want to get your hands on the parts for your bike, that will have to wait until…later. Vague timeline? Most definitely. But you understand. For a handy chart featuring prices and weights of the Shimano 105 R7100 group and comparison with the Ultegra R8100 lineup, head to “Weights and Canadian pricing for the Shimano 105 R7100 group.”

Shimano 105 R7100
Shimano 105 R7100