Shimano’s latest Ultegra Di2 groupset fulfils the potential of electronic shifting and brings class-leading braking, too

With technology trickling down from flagship Dura-Ace, Shimano's Ultegra R8170 Di2 Disc Groupset is better than it has ever been before. It perfectly balances performance with value, and the components are slick, reliable, and only create a minimal weight penalty compared to Dura-Ace. Shifting is flawless, and faster than previous iterations, while operating almost silently. This is thanks to Hyperglide+ tooth profiles, meaning that the chainrings and cassette have an improved connection with the chain, essentially improving shifting under load, across the cassette. Adding in a 12th sprocket, progression through the gears is smoother too.

Shimano has updated the new motors and circuit technology in Ultegra R8100 result in a 58 per cent increase in shift speed at the rear, and 45 per cent at the front (both of which are on a pair with Dura-Ace R9200).

This Shimano 105 Di2 groupset contains all of the necessary components needed to make the switch from mechanical to wireless electronic shifting. 

E-Tube Wires
For standard setup you will need two E-tube wires, which are included with this groupset.
One to connect each derailleur to the Di2 battery. Most frames require 1200mm wire which is supplied.
You need to select the length of second wire for connection to the front derailleur. The ideal length of wires needed depends on the length of your frame's tubes. For most small frames, 1x 750mm wire is recommended for medium to large frames 1x 900mm or 1000mm maybe be required.

Shimano R8170 Dual Control Shifters
Shimano's new Ultegra ST-R8170 brake levers bring enhanced modulation and control to every ride by employing Shimano's proven Servo Wave technology. The all-new Di2 platform, used on both Dura-Ace and Ultegra, untethers the shifters while delivering our fastest, most reliable wireless shifting. Your time on the bike is precious, let Shimano make it even better.Road riding has never been this much fun. That's because the redesigned levers have all-new ergonomics, even more precise brake modulation, and wireless electronic shifting.

Shimano Ultegra R8100 Rear Derailleur
Now simplified with a single derailleur cage length, the new 12-speed Shimano Ultegra rear derailleur packs our fastest, most precise shifting into a more approachable option. With our fastest, most accurate shifting, the new 12-speed Ultegra R8100 rear derailleur is more versatile than ever thanks to a single cage length option that is compatible with 28-34T low sprockets. The rear derailleur has battery indicator, pairing mode and compact design includes an integrated wireless unit, charger, and switch.

Shimano Ultegra M8100 Cassette
The cassette features larger driving cogs maximize drivetrain efficiency and create compatibility with both Shimano 11 and 12-speed freehub bodies. Making the Ultegra R8170 groupset compatible with 11-speed wheels. Shimano introduced their HYPERGLIDE+ technology which provides better off-road/bumpy terrain shifting with its seamless shifts both up and down the gear range.

Shimano Ultegra R8170 Front Derailleur, braze-on
The front derailleur is braze-on and you may need to purchase a front derailleur clamp.
More compact and faster than ever, the Ultegra R8150 front derailleur performs digitally precise front shifts under any circumstances.Combining Shimano's new Di2 platform and the road incarnation of HYPERGLIDE+, front derailleur shifts between chainrings with with seamless action. It has been reduced in size by 33% over previous versions and the weight cut to 116g.

Semi-wireless
Like 12-speed Dura-Ace and Ultegra, Shimano 105 Di2 is semi-wireless. This sees both derailleurs connected to a central battery, with the shifters then connecting wirelessly to the system. The rear derailleur houses the brains of the system, and is also where the groupset is charged.