It’s been said that great design is achieved when you remove all the stuff you don’t need. In my experience with eTap over the better part of the past two years, I can confirm that it is a great design. eTap HRD was officially introduced in early 2017 and it is quickly making its way onto off-the-shelf and custom builds alike. With just two buttons, the design is simple, but the function is purely incredible.

SRAM Red eTap HRD Features:

  • Paddle shifting inspired by Formula One
  • Wireless front and rear derailleurs are securely paired with shifters
  • Hydraulic front and rear disc brakes
  • Hydro HC features (contact point adjust and bleeding edge tech) are exclusive to Red eTap HRD
  • Carbon fiber lever blades and titanium hardware
  • A variety of crankset options (52/36t tested)
  • Removable, rechargeable battery on front and rear derailleurs
  • Compatible with Red, Force or Rival-level cassettes, chains and cranks
  • Utilizes AIREA wireless protocol
Dueling eTap HRD Testers -- Cannondale Synapse and BMC Roadmachine 01

Two great eTap HRD bikes — Cannondale Synapse and BMC Roadmachine 01.

Born on rim brakes, natural on discs

Last year, I had the SRAM Red eTap rim brake groupset in for review and was blown away by how well it performed. This season, I’ve spent the majority of my miles aboard SRAM Red eTap HRD — the same wireless groupset, but with hydraulic disc brakes for today’s top-shelf road disc bikes. With considerable miles aboard both the BMC Roadmachine 01 and the Cannondale Synapse — eTap HRD raises the bar for road disc groupsets.

SRAM Red eTap HRD Review

Such a tidy cockpit indeed.

Again, Red eTap HRD differs from the other electronic groups on the market (Shimano Di2, Campagnolo EPS, FSA WE) because it is wireless. Yes, it is 2017 after all and we are in a wireless world, so eTap automatically trumps all other electronic groups right off the bat. That unfair advantage has bike builders celebrating in droves. In fact, when I walked into Contender Cycles with my build, they almost wanted to kiss me full on the lips because feeding cables and wires through the integrated stem found on the BMC Roadmachine 01 is quite tedious.

So, yeah, it’s wireless and your mechanic will sing your praises, but just how does it work? eTap runs on a proprietary, military-grade wireless channel that is securely paired with each derailleur. The millions of unique combinations ensure that a peloton full of riders will never experience crosstalk.

SRAM Red eTap HRD Review

A bit of gravel aboard the Synapse eTap with winter-weight gloves on.

The batteries are removable and are the same for each derailleur. The shifters require small watch batteries that are not rechargeable, but should only need replacing every couple of years. Rotating the batteries through the charger is drop-dead simple and I just do it every couple of months whether they need it or not. Average run time is 50-60 hours, but I’ve never tried to push that since running dead is not my idea of fun.

While I’m on the subject of batteries — yes, SRAM Red eTap HRD has two of them. One advantage of two batteries is that should you run out of battery (presumably the rear mech first), you can swap the battery from the front derailleur and at least have 1×11 to get yourself home. Shimano Di2, does that process somewhat automatically, but either way, you can likely make it home with enough saddle time to kick yourself for not charging them more often. And, go ahead and pick up a spare¬†($42 at just in case.

BMC RoadMachine 01 Review / Lizard Skins Aramus GC

Responsive shifting — always.

Braking has been consistent and smooth throughout my testing. The flat mount design does look much more streamlined, but I’ve found the rear mounts (on all flat mount calipers, not just these) to be a little finicky to set up. You just have to eyeball them as opposed to the usual centering procedure. All 22 gears have been rasp-free and smooth. And, yes, you can use all 22 gears because crosschain is a relic of bad drivetrains of yesteryear.

I’ve been aboard the WiFli rear derailleur with 11-32t cassette and mid-compact 52/36t rings. This combination has proven to be amazingly-versatile as I can make my way up anaerobic 20% grades and still pedal on long descents. I’ve got zero complaints on gear jumps and love the wide range I’ve got.

Something that I’ll mention here is the battery placement on the front derailleur does limit tire clearance to somewhere around 35mm for road bikes with short stays. I couldn’t actually test that limit, but I’ve been told that it does interfere with tires in that range. I’m told by SRAM that some CX and gravel bikes with longer stays do have increased clearance (3T Exploro with 2.1″ 650b semi-slicks will apparently clear). SRAM does have a frame fit guide, if you’re curious. If serious gravel is your thing, going with¬†SRAM Force 1 is likely a better option.

SRAM Red eTap HRD Review

Detachable batteries on front and rear mech’s.

Five things I love about eTap HRD

ONE: Simplicity

There’s just no getting around it, eTap is the most intuitive shifting pattern on the market. Left shifts up the cassette while the right shifts down the cassette. Tap them both at the same time and you get a front shift. It is bonkers easy with immediate shifting and it works during the winter when you have thick, full-finger gloves on. In fact, I’ll say that it is the best year-round shifting on the market, period.

TWO: It’s wireless

Wireless — in case you’ve been under a rock for the past 10 years — is a thing. Cables, wires and stuff at home are unsightly and unnecessary, so why not on your bike? SRAM spent years nailing wireless shifting and the system uses their AIREA 128-bit protocol to establish a secure connection between shifters and derailleurs. It’s super-geeky and it works flawlessly.

THREE: Wicked-fast shifting

Electronic shifting is flat-out amazing. With just a light tap, I’m shifting with the precision of a Swiss timepiece. It’s supremely quiet too. With eTap, you can also easily shift and brake at the same time — something that’s nearly impossible on mechanical units. Once my shifting has been adjusted, I’ve never needed to re-adjust anything because there’s no cable stretch or break-in period. I’ll add that shifting under load is fantastic because the shifts happen so fast. There’s no grinding as you manually find the shifting point because the system does it for you every time. Dumping gears is also a breeze — just hold the lever down and the derailleur skips up or down the cassette in a jiffy.

FOUR: Great ergonomics and adjustability

Reach adjustment and contact point adjustment are all available to ensure that the levers are perfectly-tuned for your hands and preferences. Brake levers are comfortable and those shift paddles are easy-to-reach in the drops or hoods. And, should you need to re-adjust your shifting, it’s just a quick button press and you’re back in business.

FIVE: Disc brakes and eTap

After falling in love with eTap for rim brakes, I couldn’t wait to test it with disc brakes. The entire system is bonkers with excellent brake feel and power. I still think the Campagnolo Potenza 11 Disc offers just a touch better braking (excellent levers, power and modulation), but these are pretty close.

BMC Roadmachine 01 eTap Review

The Roadmachine 01 eTap has been my season-long tester — doesn’t get any better than this.

The Bottom Line: SRAM Red eTap HRD

Wireless shifting with disc brakes have me in a food coma. I just can’t get enough of it. Quick taps result in immediate shifting. The brake levers deliver smooth deceleration and consistent power. And, initial setup is a bike builder’s dream. Custom builds are great, but thankfully more and more OEM bikes are coming with eTap HRD, so it’s getting more affordable every day.

Buy Now: Available at

In Summary

9.4 The Benchmark

SRAM Red eTap HRD is an absolute joy to ride. The shifting pattern is intuitive and all shifts are immediate and smooth. Ergonomics are as good as it gets and more and more bikes are coming with eTap off-the-shelf -- thus making it even more affordable. The execution of eTap HRD has me wondering, "can anyone even come close to this package?"

  • Shift Quality 10
  • Braking 9
  • Ergonomics 9
  • Setup and Adjustability 10
  • Overall Value 9

About Author

A Seattle native, Jason developed a love for the outdoors and a thing for mountains. That infatuation continues as he founded this site in 1999 -- sharing his love of road biking, mountain biking, trail running and skiing. That passion is channeled into every article or gear review he writes. Utah's Wasatch Mountains are his playground.


  1. Thanks for the write-up. Seeing as you mentioned tire clearance limitations, what’s the largest you’ve mounted on your RM01? I have a RM01 UDi2 and run it with 28s, but I’m hoping to fit 32s for some gravel rides.

    • Thanks! The largest I’ve run with the RM01 is 30mm (Zipp Tangente Course R30), which measure out close to 32mm, if I remember right. Natural 32mm tires on wider rims may have trouble, but I haven’t tried them. I can try to keep you updated once I do though.

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