All the details about SRAM's brand-new, groundbreaking wireless electric drivetrain, just revealed in Europe.
SRAM’s new Red eTap wireless drivetrain hits Shimano Di2 and Campagnolo EPS where they’re weakest, and matches their strengths. It’s more modern, more savvy, and more user-friendly.
– It’s electronic.
– Wireless with a custom protocol (no Ant+ or Bluetooth) called Airea.
– New shift logic — only two buttons, left shifts to easier gear, right to harder gear, press both for front shift.
– Quick setup, complete build in less than 15 minutes.
– Extra shift buttons, called Blips, available (including TT setup).
– 45 minutes to charge batteries, 1000-kilometer run time.
– Weight within spitting distance of Red mechanical.
– Only cable-actuated brake levers are currently available.
ETap is an electronic system, just like Shimano’s Di2 or Campagnolo EPS. But it takes electronics a step further, removing the wiring harnesses that both those groups rely on, and switching to an entirely wireless communication between the shifters and derailleurs. Each component in SRAM’s new system is self-contained, with its own battery and wireless transmitter. They just need to be bolted to the frame, synced together, adjusted, and you’re off.
Shift logic is changed completely. Shimano and Campagnolo both chose to keep their shifter function virtually identical to that of their mechanical groups — SRAM emphatically did not. I think SRAM’s new shift logic is more logical.
There is only one shift paddle per shifter. The left shifter paddle shifts the rear derailleur inboard, to an easier gear, while the right shifter shifts the derailleur outboard, to a harder gear. If both buttons are pressed at the same time, the front derailleur shifts.
Left, easier. Right, harder. Both, front shift. It’s that simple.
The rear derailleur acts as the ‘brain’ of the system. In wireless terms, it’s the master and the front derailleur and shifters are slaves. It’s about 20 percent bigger than a standard Red rear derailleur, and weighs 239 grams, almost 100 grams heavier than a standard Red rear derailleur. That’s also 26 grams heavier than a Dura-Ace Di2 rear derailleur, which doesn’t have its own battery.
The Red eTap derailleur features a carbon cage and ceramic pulleys, just like the mechanical version, and installs just like a normal rear derailleur.
A small, rechargeable lithium ion battery is attached to the back and weighs 24 grams (this weight is included in the 239-gram figure). This battery will last about 1,000 kilometers, according to SRAM. It is identical to the battery used on the front derailleur, and will drain quicker as it is used more frequently. That means that should it run out, a rider can swap the front derailleur battery to the rear and continue onward with a functional rear derailleur.
Both front and rear derailleurs have small LED lights that indicate battery life with every shift. A flash of green is good. A flash of red indicates that the battery is down to 25 percent, about 250 kilometers. Repeated red flashes indicate imminent singlespeeding.
The front derailleur uses the same Yaw tech as SRAM’s mechanical derailleurs, so it doesn’t self-trim like a Di2 derailleur. It does overshift and then settle back into position, to make shifts faster.
An aluminum outer cage is matched with a steel inner cage for durability and a composite tail to drop some weight.
The front derailleur weighs 180 grams; about 75 grams more than a Di2 front derailleur (which, again, relies on a separate battery) and will cost you $370. The rear derailleur costs $590.
The single, large paddle on the shifters is nearly identical to current SRAM mechanical shifters, though it doesn’t move as far before a shift is initiated. SRAM says it went through over 40 different versions of button placement, keen to find the most intuitive, but its original design turned out to be the best. Given that all three major brands have a shift paddle in this exact spot, this fact isn’t surprising.
Small CR2032 batteries, the same as those found in many power meters, heart rate straps, and other small devices, power the shifters. These are not rechargeable, but will last at least two years, according to SRAM. The shifters are simply sending a signal, and function in a similar manner to the key beeper you use with your car (which lasts a very long time). The battery lives behind a small cover on the top of the hood.
The hoods themselves have gone on a diet. They’re slimmer than their mechanical siblings. The rubber material is the same, and shape is generally the same, with a similar knob and nearly identical reach to the brake levers.
Those brake levers, which are carbon fiber, are much stiffer than before, and it’s noticeable when braking.
At 260 grams per set, the shifters are 30 grams heavier than Dura-Ace Di2. They’ll set you back $580.
Shimano has its “sprint shifters,” SRAM has Blips. They’re small button pods that attach, via wires, to ports in the shifters. The wires come in four different lengths, and two of them can be plugged into each shifter. That means you could run a total of six shifters on your handlebars, if you want to look ridiculous.
The Blips weigh only 6 grams, and cost $200 for a set of four.
For those using aero bars without a standard road shifter, the Blips can plug into a Blipbox instead. The Blipbox has all the same wireless tech as the road shifters, allowing the Blips to talk to both derailleurs. The Blipbox weighs 31 grams and costs $300.
Setup is easy. Very easy. With no cables to fiddle with, or internal routing to curse, setting up a brand-new bike takes less than 15 minutes. One of SRAM’s mechanics set up a time-trial bike’s shifting, a process than would normally take at least three nights and nine beers, in less than six minutes.
If you’re not running Blips, road setup is even easier. Simply mount up each part, and start the simple syncing process by holding the “function” button on the rear derailleur, which is right next to the indicator LED. Hold that down until it glows green, then move onto the front derailleur and do the same. Repeat with the shifters. Green lights means everything is paired up and ready.
Limit adjustments on both derailleurs are nearly identical to a mechanical setup. You simply need to back the rear derailleur limits out a bit so the motor isn’t working against the physical limit, as that could damage the motor.
Once limits are set, micro adjustments can be made using the function button on the back of the shift paddles. Pressing the function button on the right shifter, then pressing the right shifter paddle (this is easy, just pinch the paddle and push in), the rear derailleur will microadjust to the right in 2/10mm increments. Do the same with the left shifter and it will microadjust to the left. Hold both function buttons and the front derailleur can be adjusted in the same way.
There is no ‘adjust mode,’ as with Shimano. Whenever a function button is held down, that’s adjust mode. Let it go and the system will shift normally.
Will I get hacked?
Well, nothing is un-hackable. That much is clear. It would be possible to jam eTap with some heavy tech artillery, driving next to your intended target on a motorcycle. But in reality, no, you won’t be hacked or jammed or anything of the sort.
ETap uses a custom wireless protocol SRAM calls Airea. It’s a high speed, low latency, low power system designed using 128bit AES encryption and strict pairing rules. That means you can only pair one set of shifters to a bike, so you can’t shift your buddy’s bike.
SRAM has over 1 million kilometers on the system now, in the real world, and has yet to have a single issue. About fifty SRAM staff and media rode together last week, and each bike was only shifted by its own shifters.
SRAM has had some high-profile durability and quality problems in recent years, and seems intent on leaving those behind. The company borrowed much of its testing from other electronics giants, as a system like eTap runs into different sorts of problems from a mechanical or even a wired electronic system.
Each component was put though a pile of tests, including:
– A tumble test, developed by Nokia for cell phones.
– A vibration test, used a test from auto industry for unsprung components (sensors in the wheels and such), which simulates 10 years of hard use.
– A battery security test, which tried to rip the batteries off the derailleurs.
– It passed worldwide standards for dust and water ingress — the highest standard, to be precise. The system is waterproof to 1 meter and can handle aggressive power washing. SRAM even made a test machine that power washes from every possible angle for 30 minutes.
– A thermal cycling endurance test, which put the components through extremely low and high temperatures and humidity, and a thermal shock test, meant to replicate having your bike in the back of your car on a hot day then hitting it with a bucket of cold water.
– A static discharge test.
– In addition to the testing, SRAM built a clean room in its factory in Taiwan to build everything, and everything is built in-house.
Media attending SRAM’s secret launch last week were treated to three good rides on the new group through the rolling terrain outside the company’s German headquarters, totaling about seven hours of riding.
The new and unique way that SRAM has laid out its shift buttons, something it calls shift logic, is spot-on. It’s what Shimano should have done with Di2, and what Campagnolo should have done with EPS. For more on why I think that, look over here.
That said, eTap is not perfect.
The rear shifts are slower than with Di2, and shift speed is not adjustable as it is with Di2. This is partly down to the Red cassette, which shifts slower than Force and most Shimano cassettes. When I tested the system with a Force cassette, it was much faster, though still not as quick as Di2.
SRAM says it tested shift speed extensively, and the speed built into the system is the best compromise between predictability and aggressiveness. I disagree. Make it faster, please. These are motors we’re talking about, it should just be a firmware update.
Front shifting is impressive, as it is with all electronic systems. Electric motors are powerful, and that helps with big front shifts. Jumping from small ring to big ring while under power is no problem. Again, Di2 feels a bit firmer, perhaps due to its stiffer chainrings, but eTap is tantalizingly close.
The buttons themselves have a nice, solid, audible click. They’re firmer than Di2 buttons, which are a bit mushy, and require less force than EPS buttons, which closely mimic the mechanical version. It is impossible to accidentally hit the wrong button, because there’s only one on each side.
SRAM designed its Blip external shift buttons so that they couldn’t be pushed accidentally, but they also made them almost too difficult to push, particularly if they’re hidden under bar tape. I like Shimano’s sprint triggers and how easy they are to smack. I rarely hit them accidentally. The Blips could stand to be a bit more sensitive.
Wireless is fantastic. Setup is unbelievably easy. Function is almost perfect — a few small changes before the group goes into full production would solve the few remaining issues.
The eTap shift logic, that left/easier right/harder system, seems primed for a single-ring setup. SRAM loves single-ring setups. The math, then, is not difficult in this case.
When asked about wireless mountain bike drivetrains, SRAM employees refused to comment, while smiling like they knew something we don’t.
Trickle-down is tricky, in this case. Many of the electronic components used in Red eTap simple can’t be made much cheaper unless volume goes up dramatically. That makes dropping eTap down below the Force level (which could be achieved with changes in the materials surrounding those electronics) quite difficult. That said, from a commercial standpoint SRAM has little choice but to figure out how to build cheaper eTap. Expect e-Force, and maybe even e-Rival, in the next few years.