Shimano 105 Di2: the people's group goes electronic

The Shimano 105 groupset is coming up on its 40th anniversary with great fanfare and feels younger than ever thanks to the ultimate upgrade: the Di2 version. That's right, it's finally here - the 105 has gone fully electronic!

The Shimano 105 R7100 Di2 finally brings semi-wireless electronic shifting to its mid-range groupset, and an extra sprocket to boot, bringing it in line with the best in the business, Dura-Ace and Ultegra. Some deplore the lack of an option shoe brakes, but if you want the most powerful hydraulic braking and electronic shifting on the market, this is probably the most cost-effective Shimano groupset for high-end road bikes. The Shimano 105 Di2 groupset is the culmination of years of research and development, where reliable wireless shifting, extra gearing, and an exceptional braking system mark a new era in performance for everyone.

In this article, we'll review all the components of this new groupset and see if it will truly change the way electronic groupsets are perceived.

Shimano Di2: the intelligent drivetrain

Before we introduce the 105, let's start by understanding what a Di2 system is, one of the most advanced electronic shifting systems. Shimano Di2, or Digital Integrated Intelligence, is a continuation of the NEXAVE C910, a beginner's electronic system that debuted in 2001 and even included an electronically controlled suspension option that automatically adjusts settings based on road conditions and riding speed, which was truly revolutionary for its time.

It was in 2009, that Shimano introduced the Di2 system, which really changed the game in terms of shifting on a bike. It also sparked a lot of debate, like all new developments in cycling - because there's nothing cyclists of all stripes love more than debating the superiority of one component or another (example:carbon frame vs. aluminum or more related to our topic:electronic vs mechanical transmission).

Since that first introduction two decades ago, Shimano's electronic technology has evolved to offer one of the most advanced shifting experiences for a wide range of practices, from road to MOUNTAIN BIKING. Today almost all high-end road bikes have versions equipped with some form of electronic shifting, so it's safe to say it's been adopted. The purpose of this system has always been to offer additional comfort and increase the precision of the gear change, even in the most difficult situations, such as the need to change gears when climbing Alpe d'Huez. 

The Di2 system is a series of technological components, designed to provide a smooth, fast and almost frictionless transmission. From the transmission to the shifting and braking levers, this system is designed to make shifting and braking as efficient as possible. For example, to combat the premature wear and friction that reduces the power of a misaligned drivetrain (that nasty mechanical clanking that comes out of your chain as you pedal), Di2 automatically senses the position of the chain as you shift and adjusts the front derailleur to the optimal position.

Because shifting is not always done one at a time, the Di2 is programmable to allow you to shift multiple gears at once by holding down the shift button. This feature is perfect for those big shifts. All of this control flows between the levers, the system interface and the drivetrain components through small Di2 mechanical units located in the front and rear derailleurs that precisely control the movement of each derailleur to provide a perfect, clean shift every time. So that the motors can provide faster and more reliable shifting in all conditions and on all terrains.

Shimano 105 Di2, the electronic little brother

To learn more about the little brother of the already famous Ultegra and Dura-Ace Di2, let's look at its 5 main points.

1- Goodbye to the mechanical groupset.

From now on, the Shimano 105 will only be available in this new electronic and semi-wireless version. If you want a mechanical groupset from Shimano, you will have to think about the Tiagra.

2- Semi wireless Di2 technology.

This is the same as the high-end Dura-Ace and Ultegra Di2 groupsets. The push buttons have no cables, but the front derailleurs are operated by a cable connected to the battery (integrated in the seatpost).

3- 12 sprockets cassette. 

Like the best road groupsets, the 105 adopts the 12-speed cassette. The double crankset option is retained.

4- Goodbye to brake pads.

The new groupset also does without brake pads. There will only be hydraulically operated disc versions.

5-Unprecedented carbon wheel design.

Shimano intends to make carbon wheels more popular and offers them tubeless ready. A competitive all-carbon wheel that combines aerodynamics, stiffness, weight and cost.

Now that we have reviewed these points, let's look at each part of this group.

Shimano 105 Di2 - Photo: Shimano

Interface

The new Shimano 105 dual control levers feature excellent ergonomics, where a raised hood top and new lever shape improve comfort and control in all riding positions. Braking is also optimized with a lighter, smoother lever action and a wider braking control area.

The levers use Shimano's proprietary wireless IC that offers high safety, fast processing speed and low power consumption. Compared to other wireless platforms, you get a significant decrease in the likelihood of interference, faster shifting speeds and longer battery life. And thanks to the use of a single rechargeable battery housed inside, charging is simple and the battery is protected, ensuring stable and reliable shifting at all times.

Advanced transmission technology

With the adoption of a 12-speed cassette, riders who will take advantage of a Shimano 105 Di2 now have the high and low range they need, as well as smart intermediate gear progression. This is the result of optimized drivetrain components, which include 11-34 and 11-36 cassette options and 50-34 and 52-36 cranksets. Together, they offer low, even sub-1:1 gear combinations that allow riders to tackle steeper grades and better control their efforts because the gear steps are closer together, so you can always find a comfortable cadence. Very good for touring cyclists and intermediate riders.

As for the derailleurs, the rear derailleur has an internal motor connected to the external battery built into the seat tube. It has been optimized for 12-speed shifting only and the pulleys have 11 teeth. According to Shimano data, electronic shifting reduces the time needed to shift gears by more than 50% compared to mechanical shifting. The front derailleur is connected to the battery by the same cable. The chain guide is made of steel with an anti-corrosion chrome finish and has been optimized for 12 speeds only. The battery (SD-300) is the same as the Shimano Dura-Ace and Ultegra Di2, with an estimated range of 1,000 km per charge cycle. Battery status can also be monitored with a small indicator light built into the derailleurs, which changes from green to red to indicate a low battery condition.

Braking

As mentioned earlier, Shimano's new 105 groupset features a new version of pad brakes. While this may come as a shock to all the purists out there, Shimano has put all of its faith and development into these disc brakes. Like the latest Dura-Ace and Ultegra groupsets, the new Shimano 105 features a braking system that is quieter, easier to maintain, and extremely controlled and powerful. Advanced features include a quick initial contact point with a control zone control area and a 10% larger gap between the shoe and rotor, ensuring quiet operation. Amateur mechanics will also appreciate the easier bleeding process, which can be done without removing the caliper from the frame. If you're not one of those amateur mechanics yet, check out our blog to learn the basics of proper maintenance your road bike.  

Connectivity

The Shimano 105 Di2 uses a hybrid system, with a wireless cockpit combined with a wired connection between a single battery, housed in the seat tube, and the front and rear derailleurs, ensuring absolute reliability in all conditions. And like Dura-Ace and Ultegra, the Shimano 105 Di2 system is highly customizable using Shimano's user-friendly E-TUBE PROJECT app on your smartphone.

E-Tube project interface - Photo: Shimano Steps

With E-TUBE PROJECT, you can configure your drivetrain the way you want it, by adjusting the shifting speed, changing the number of shifts per button press, and using the synchronized and semi-synchro shifting functionality.

You can also pair the system with third-party bike computers, such as Garmin and Wahoo, that allow you to control gear selection or battery status.

Conclusion

Cycling is all about of training and marginal gains, and that's what the Shimano 105 Di2 aims to do for a group of riders who have not yet had access to an electronic derailleur. With the arrival of this group, Shimano hopes to make electronic derailleur technology more accessible to more amateur cyclists. Certainly, the technology is there and it is a system that, for an enthusiast, will allow thousands of kilometers of happiness.

However, the final price of the components is higher than in the previous mechanical version. The recommended retail price of this new 105 is, depending on the components chosen, about 1,800 euros, certainly not cheap. So there is still a long way to go before we see the real democratization of electronic groups, but the trend is definitely there. Let us know in the comments what you think about electronic bands and check out our collection of bikes with electronic groupsets to choose the best one for you. Enjoy the ride!