By Philip Harwood While the double diamond frame design of a road bicycle has changed little over the past century, just about every other component of the modern bicycle has changed and progressed into the wildly futuristic machines we are accustomed to gawking over today. Long gone are the days of yore, when the first Tour de France contenders had two speeds, and required flipping the rear wheel to change speeds. Nowadays, we are literally spoiled with 11 and 12 speed drivetrains. At the forefront of this multi speed drivetrain technological revolution is electronic shifting, and the major players (sorry Campy fans) are Shimano and SRAM. The Players Shimano Di2: Di2 stands for Digital Integrated Intelligence, and is available in Shimano's higher-end offerings, which are Dura-Ace and Ultegra for the road and GRX for gravel. SRAM ETAP AXS: SRAM's electronic systems are also only available in their higher end groupsets, which include Red and Force for road and gravel. Both drivetrains feature precise electric shifting, clutch rear-derailleurs, hydraulic disc brakes, multiple gearing options, Bluetooth functionality, satellite shifter buttons, and the ability to customize setup and control using mobile phone apps. The Differences Shimano has eleven speeds, aluminum crank arms, standard cassette body, mineral oil brake fluid, a hardwired system, and the Shimano E-Tube App for functionality. SRAM has 12 speeds, is available in rim brake, has dedicated 1x and 2x drivetrains, carbon crank arms, proprietary XD Driver cassette body, DOT fluid, wireless shifters and derailleurs, and the SRAM AXS app. Shimano is hard wired (not Bluetooth), so everything has to be connected with wires, usually routed inside the frames tubes. When set up correctly, with a bike designed with Di2 in mind, you get a clean, minimalist look. The biggest differences are in wires/price. Obviously, SRAM wireless is much easier to set up, will retrofit almost any bike, and has a crisp, clean look. SRAM is also much more expensive Modern components like handlebars and stems can hide the junction box in the bar end and keep the wires internal, which looks great, but can be labor intensive to set up. Shimano is less expensive than SRAM, but still features a hefty price tag. I am a little biased, I have been riding a Dura Ace Di2 drivetrain for the past three years and have had no major issues with it. Brake pads wear fast if I ride in the rain and snow. Battery life is incredible, and I usually charge it every other month or so (I ride at least 5 days a week). The Bluetooth connectivity with the E-Tube app is incredible and allows you some customization. You can set the buttons on top of the shifter hoods to do a lot of neat things, like scroll through your Garmin screens while keeping your hands on the bars! Mine is set up in Synchro Shift mode, so it automatically shifts the front derailleur based on the position of the chain on the cassette. So I only use the right hand shifter. Genius, and pretty straightforward to set up. I have ridden both the Dura Ace and Ultegra versions, and I would go with the Ultegra version. The shifting/braking performance is identical and it’s a lot less expensive. On the other side is SRAM. It has really become a favorite of bike mechanics because of the ease of installation without wires. The extra speed, bigger gear ratios, and connectivity across road and mountain groups are solid arguments for SRAM. It also looks super clean and represents the latest in technology. You can program the SRAM shifters to do lots of different things, including controlling a wireless dropper post. The batteries are interchangeable, so if the rear derailleur dies, you can swap the front derailleur battery in, and continue riding. Shimano is due to release the next version of Di2 next year, and is rumored to have less wires, 12 speeds, and bigger gear ranges. Both companies have fostered great competition in the battle for drivetrain supremacy!