SRAM Hydro R Hydraulic Road Disc Brakes introduction and ride review

After about a year of teasing (and plenty more years testing), SRAM has finally unveiled their hydraulic disc and rim brakes for road bikes.

Called SRAM Hydro R (as in Hydraulics for Road), they join the lineup as top-level options for the new SRAM Red 22 and Force 22 11-speed groups. Mechanical rim and disc brakes will still be available as well as all-new very similar 10-speed S-700 series hydraulic brakes will be available, too. The idea was to make hydraulic brakes available to all current SRAM road groups, whether they’ve been on your bike for five months or five years, and give riders more options. Heck, they’re even offering standard and “moto” (left hand brakes the rear wheel) setups.

Options are good, but the real reason for moving to hydraulic brakes is to improve power, control and modulation in all conditions. The Hydro R rim brakes produce more braking force with less hand effort, in and of itself a great feature. It’s also a closed system, so it should feel as good in a year as it does on day one. And the disc brakes are even more powerful…


SRAM Hydro R hydraulic road bike brakes prototypes

About three years ago, they made an external master cylinder placed inside a stem, thinking it a good idea to make it compatible with any standard mechanical lever. But, they couldn’t fit it in anything less than a 110mm stem, and as SRAM’s road groups gained traction, they decided it was better to create a completely closed system.

This was before the UCI allowed disc brakes on cyclocross bikes, so they were looking at rim brakes. They wanted something that could quickly retrofit to any single-bolt brake mount (i.e. virtually all road bikes) that would offer better power and modulation while also eliminating cable drag associated with ever more complex internal routing frame designs. Then, of course, disc brakes became legal, so they started working on those, too.

SRAM Hydro R hydraulic road bike brakes prototypes

What they found was quite interesting. Despite the rim essentially being a much larger diameter rotor than, say, a 160mm rotor, the disc brakes turned out to be substantially stronger. The brake force to lever force ratio came out with discs clearly on top:

SRAM Hydro R hydraulic road disc and rim brake power comparison

From there, they strapped on weight vests to get up to the 250lb system weight and started bombing down hill. Hydraulic brakes product manager Paul Kantor said they expected to boil the fluid during long descents while dragging the brakes, but that didn’t happen. Nor did it overheat during very rapid deceleration, but those tests did cause quick pad deterioration. So they switched from drilled alloy-backed pads to solid steel, and that held up better. The alloy backed pads with holes in the back were getting odd temperature spikes. They also switched to a different organic compound, a variant of what’s used on the mountain bikes. Metallic and semi metallic created too much heat.

With heat testing as a non-issue, and more power available to the rider, are there any other benefits to going to disc? Possibly. They found that sustained braking for five minutes generated about 550 watts of energy on a rim brake with carbon fiber rim, which made enough heat to blow out a tire. However, on discs, they could drag for 12 minutes, producing about 800 watts, with no brake failure and, obviously, no rim/tire failure.

SRAM Hydro R Hydraulic Road Disc Brakes introduction and ride review

Things can definitely get hot outside normal operating conditions.

With all that said, these testing conditions are far beyond the “normal operating range” of typical riders, even those riding in the Alps. They did test disc brakes with more initial bite and a higher overall brake force power. The only benefit was improving the “parking lot experience” with more dramatic stopping power, but modulation and control suffered. And, as many readers have commented, it’s already pretty easy to lock up a road bike’s tires, so massively increased power wasn’t the goal. More control and improved safety was, and they say they’ve nailed it.

And, for the rim brakes, more power doesn’t mean you’re more likely to overheat your rims. It does mean you’ll be able to brake harder and later, but for less time. You’re creating the same amount of heat energy during braking to accomplish a set amount of deceleration. And, ultimately, tire traction is going to be the real-world limiting factor.

Kantor says there are two break in periods with the disc brakes. The first is the usual pad bed in procedure. Then, after the first few sustained braking efforts (say, dragging down them down a hill for a few minutes), the pads will heat up and change a bit, and then power should increase slightly.

A few other technical points they mentioned:

  • DOT5 has a boiling temp of 380ºC, but even when rotor temps hit that or higher, it’s not immediately transferred to the fluid. In the unlikely event it did boil, it would cool rapidly (a few seconds) and should be fine.
  • Ambient temperature had no noticeable effect on the system.
  • For rim brakes, heat transfer’s even less of an issue. The rim brake pads dissipate heat quickly, so very little of it’s transferred to the caliper arms, and even less is transferred to the “toilet tank”, as they affectionally call it, where the fluid is.


SRAM Hydro R Hydraulic road brake lever cutaway

The head of the unit is the same for both disc and rim brakes. It has a new master cylinder design, quite different from the Taperbore levers on Avid’s mountain bike brakes.

SRAM Hydro R Hydraulic Road Rim Brakes introduction and ride review

Like their Avid brakes, it uses DOT5.1 fluid, and it’ll use the same bleed kit, and Avid’s Pro Bleed Kit is arguably the best one out there.

SRAM Hydro R hydraulic road disc and rim brake cutaway images

The Hyrdo R disc calipers use 19mm front / 18mm rear pistons. The caliper and piston ratio are different than what you’ll find on mountain bike systems, it’s not just a mountain bike system ported over for the road. The smaller caliper on the rear helps reduce the likelihood that it’ll lock up.

SRAM Hydro R Hydraulic Road Rim Brakes introduction and ride review

We mentioned that the new Connectamajig will be offered for use with this, and it’s aimed at the OEM manufacturers to ease assembly line efforts. SRAM’s product managers were careful to point out that it’s not really designed to be a quick disconnect for travel frames, it’s primarily to make installation easier.

Without a Connectamajig, you're unthreading the hose from the caliper to run it through a frame, which will almost certainly require a full bleed.

They’ll have inline and caliper mount versions, and they’ll have different seals and rubber parts inside than what’s available for the Reverb since one uses DOT5 and the other uses suspension fluid. For frames using the caliper mounted version will have the Connectamajig incorporated into the Banjo, which is their preferred method for using it, but it’ll require a slightly larger hole in the frames (about 7.5mm diameter) to feed the line through. The goal is to reduce or eliminate a factory’s need to bleed the system during the installation process, something that could lead to inconsistencies in performance by the time the bikes hit your local shop’s floow.

SRAM Hydro R Hydraulic Road Disc Brakes introduction and ride review

One common question leading up to disc brakes on road bikes is how a tiny rotor can compare to the massive “rotor” that is the wheel’s rim. I asked Kantor how they got more power from a much smaller “rotor” with the disc brakes, and this was his reply:

“Disc brake friction materials are much better for braking but no good to make a rim out of. There are a lot of things that go into it, but this is the biggest factor.”

I also asked how they compared to BB7 mechanical disc calipers:

“Yes (we benchmarked these against the BB7’s. They’re) a little less grabby off the top because the BB7’s use sintered pads. Power is comparable. And the pad wear rate is similar to our other organic materials.”

SRAM Hydro R Hydraulic Road Disc Brakes introduction and ride review

The bottom of the pads are angled to make for quicker, easier wheel changes…particularly important if these are ever to be adopted by the pro peloton. Be nice if this transferred to their mountain bike brakes, too!

SRAM Hydro R Hydraulic Road Rim Brakes introduction and ride review

The Hydro-R Rim calipers are an incredibly simple system. Fluid comes in, makes a U-turn and pushes a small piston up. Both arms rotate on a single pivot…

SRAM Hydro R Hydraulic Road Rim Brakes introduction and ride review

…and the piston’s movement is minimal. At left, the brake is open, and at right, it’s closed to stop the wheel from turning. Note the wide part of the piston sticking up just a couple millimeters more. Here’s a close up:

SRAM Hydro R Hydraulic Road Rim Brakes introduction and ride review

That’s it. That tiny bit of movement is more than enough to lock up the wheels.

SRAM Hydro R Hydraulic Road Rim Brakes introduction and ride review

But you have to move the levers this much to do so, and that’s the key to these brakes’ incredible modulation. Unless you over react or just grab a fist full of brake, you have very fine control over how much power you’re putting into the brakes. And because it’s fully closed, and there’s no cable friction, it’s unbelievably smooth.

They’re compatible with rim widths up to 28.4mm, and the contact adjust knob and quick release knob on the top of the caliper are super easy to use and provide a good range of adjustment.

SRAM Hydro R Hydraulic Road Disc Brakes introduction and ride review

The HSX and other rotors will be sold separately, so you buy only the size you want/need. They’re requiring OEM spec of 160mm for pavement, but offering 140mm for cyclocross. The 160mm rotors are designed around a 250 rider/bike combined max weight. Larger riders should opt for even bigger rotors (and make sure their frame and fork can handle 180mm+ rotors!). Sorry tandems, this isn’t for you yet.

SRAM Hydro R Hydraulic Road Disc Brakes introduction and ride review

The S-Series Hydro-R brakes are your 10-speed options. SRAM will continue to support 10-speed systems, and the current 10-speed Red and Force systems will stay in the line. The S-700 Hydro-R levers and brakes allow anyone to add hydraulic brakes to their current 10-speed SRAM group. The front shifter is YAW compatible, meaning it’s designed for 2012 Red, but cable pull is sufficient for older, non YAW 10-speed systems. It just won’t have the two position trim for the big ring.

SRAM Hydro R Hydraulic Road Rim Brakes introduction and ride review

The main differences in the RED and S-700 brakes are titanium versus stainless steel hardware and carbon versus alloy shifter/brake levers. Functionally, they’re identical.

For TT and Triathlon bikes, they’re “always working on new stuff”, which should be interpreted as hydraulic levers and possibly even dual bolt mount brakes are in the pipeline.



Did the road discs produce higher overall heat than MTB systems?

“No, haven’t seen peak temps go any higher as what we consistently see on mountain bikes.”

What’s dissipating the heat in such a minimal package?

“The sustained temperatures are typically lower (on the road), and the caliper has a more open construction with more air flow through it.”

Are current road forks and skewers up to snuff?

“Yes, they’re not all that different from mountain bike QR skewers.”

Do you see thru axles as improving the road bike with regards to brake performance?

“We’ve done some testing, but we couldn’t tell an appreciable difference.”

SRAM Hydro R Hydraulic Road Rim Brakes introduction and ride review

SRAM made a big deal about aerodynamics with the 2012 RED launch, so it was a little odd they didn’t mention the minimized frontal profile of the hydro calipers. Side to side, the Hydro-R calipers stay within the frame’s width much more, which leads us to think they’ll contribute to an overall more aero bike/parts package. Plus, it just looks better. For TT/Triathlon bikes, that’s an obvious boon, and the slippery feel at the lever will remain regardless of the convoluted hidden cable routing some aero bikes employ.


Hydro-R Rim Brakes: There’s a tiny bit of free stroke at the lever, about 4mm at the bottom of the lever, before the calipers start to move, which isn’t noticeable while riding. The amount of lever pull is greater than the movement of the caliper’s piston, which gives you a ton of fine modulation. The feel is head and shoulders above cable systems. That said, it’s still braking on a carbon rim. As good as Zipp’s rims and pads are, I would have like to test them on alloy rims, too. Even SRAM’s test results (see chart up above) show higher braking power on alloy rims.

Hydro-R Disc Brakes: Given my history with disc brakes and steep roads, this was one item I was very, very keen to test. It would either seal the deal that road bikes and disc brakes don’t mix, or restore my faith in systems engineering to make it work. I’m very happy to say it’s leaning towards the latter. We tested them on some long, steep and wicked fast descents (I’ll add Garmin map data as soon as I can), and the disc brakes were far more confidence inspiring than the rim brakes. I felt like I had more control and could stop quicker. On one particularly long, straight section, I got up to 43mph then grabbed as much brake as I was comfortable with and slowed a crawl. I repeated this quickly three more times in rapid succession, sprinting then emergency stopping, and there was no fade. I’d liked to have been shuttled to the top again and let them drag all the way down then see what was left at the bottom, but that’ll have to come when we get our own set in for long term testing.

Was it perfect? No. There was still a bit of the warbley sound that Avid and other brand brakes sometimes make, and at the end of one ride the rotor was lightly-but-consistenty rubbing the outside brake pad on the front wheel. These sorts of things might delay uptake among pure roadies, and they should find ways to remedy this as it’s more noticeable on skinny tires. Kantor said the pad retraction on the Hydro-R calipers is slightly greater than on their mountain bike calipers, but it might need to grow a hair more. Or, the set up could just take a bit of tweaking…these were some of the first ever rides on the brakes after all. For now, I’m optimistic. First impressions are good, and the general consensus among the other journalists seemed pretty positive. For me, the most telling statement is that, despite past experiences, I’m really looking forward to getting these on my own bike for long term testing.


So, are disc brakes the wave of the future? Without disclosing any names, Kantor says OEM buyers for “major bike brands” have been more interested in the disc brake system for both road and cyclocross. And they’ve been working with frame manufacturers to develop bike/component systems that take full advantage of the new parts. And speaking of the future, they do have demand for under-the-bottom-bracket mounted rear brakes, common on TT/Tri bikes, which could mean a dual mount rim caliper.

Both the RED and S-700 hydraulic brakes will be available this July. Check the RED 22/Force 22 drivetrain post for a complete breakdown of pricing, availability and actual/claimed weights.


  1. off-roadie on

    I’m still trying to read the stuff from over the weekend, slow down! (just kidding, I wasn’t really planning to work today anyway)

  2. Andy on

    Looking good, though they might be a bit too powerful for bikerumor. An upgrade to kettle siccc rotors should remedy that defect 😉

  3. Jake on

    Still turkey-gobbling, eh? I really wish SRAM would own up to the problem and address it outright. Explanations like, “Some frames just resonate more than others,” or “Some frames can’t handle the power of the brakes” (psssh, XO trail? Yeah, right) only further tick me off. Come on, Avid.

  4. Trey R on

    What I wonder more than anything is how super light road wheels will deal with the braking forces from the hubs. With rim braking, there is no torsion forces on the wheel, where as disc brakes put A LOT of torsion on them. Otherwise I think disc brakes rule considering companies can design rims better without having to incorporate a braking surface and structure into them.

  5. Tandumb on

    Electronic shifting, sub 18lb bikes, hydro brakes… These are glorious times folks. What a great time to be cyclist.

    Sram delivers XX1 for MTB, now this for Road… Buuuuut what’s the good news from Shimano these days?

  6. wheelguy on

    Been waiting for this day for years! Hydraulic road disc brakes can’t come soon enough. Hopefully Shimano will have something ready later this year. Super-light carbon clincher rims with hydraulic discs will be the perfect combo.


    I e-mail a link to this article to my mechanic. And in caption I stated if these are release on July 1, they will be on my bike the second! Help me make it so. Knowing my mechanic he is already lining up pre-order’s

  8. Shanghaied on

    @Trey R: For one thing radial lacing will be out of the question. When I learned to build wheels the advice was always to use 3-cross, at least for the disc side, and all of the disc wheels I’ve seen had at least 2-cross. Good thing too as I think radial lacing is quite pointless.

  9. chrisc on

    I agree with wheelguy this has been a long time coming.When you think about it ,rubbing two bits of rubber on your wheel rim to slow down is so antiquaited. Now we just need to convert everyone to tubeless tyres and dump the innertubes. What other wheeled sport still uses them?
    Tractor pulling maybe.

  10. wonko on

    Maybe it’s just because of my MTB background but I find the hydraulic disc brakes from a major company much more exciting than Nintendo shifting systems. I can very well see myself substituting the BB-7 road on my bike for these. The hydraulic rim brakes seem to me a tad pointless if there is a disc brake option but if they comply with UCI reglement they are probably quite interesting for a race bike.

  11. Brian on

    chrisc – nope, tractor pull vehicles use beadlock rims without inner tubes. We’re the only wheeled sport that still uses inner tubes….

  12. nick on

    Still an Avid hydro brake, still uses DOT fluid. Shimano (and Magura, for that matter) have been ahead of the game with mineral oil, not looking forward to bleeding these. And god knows it’ll be twice/brake

  13. Gravity on

    Wait until Shimano shows off ther production DI2/hydro lever. It’s going to make this stuff seem like a 1980s bag phone alongside an iPhone.

  14. Joshua Murdock on

    I always trash Sram… and if these are anything like their other brakes they’ll be more trouble. But, it is really cool the see hrydo and hrydro disc brakes for road bikes hitting production. This is progress.

  15. CXisfun on

    Right on Nick. I hope we’re both wrong, but I doubt we are. Avid brakes are the worst there are. Buyers can hope that they only need to bleed twice per brake, that’d be a big improvement.

  16. a on

    I gotta say this quick red upgrade does not show integrity from sram. I would be pissed if I had bought a brand new red group right before this came out (knowing I could have found it discounted). shop owners are also probably really crabby towards sram as they should be. shimano shows a lot more confidence with their product.

  17. Andy S on

    @ChrisC & Brian, motocross/supercross still use tubes, can’t speak for superbike/crotch-rocket racing. However, I am all for a tubeless bicycle future… just waiting for a Zipp Firecrest tubeless option.

  18. Mike on

    I can’t stop laughing at those videos. “Follow these steps with your trained octopus and you’ll be riding within a matter of just hours!” Now I know why I side stepped high end mountain bikes for so long.

  19. Andy S on


    Ahhh you couldn’t be more incorrect, I happen to be a supercross guy and know a supercross racer or two (been a pit guy on track, you might have seen me on tv). They do in fact use tubes and not the “moose” that you speak of. It has been tried but to no luck, the racers do not like it (yet).

    Also, I am guessing that you don’t watch moto or supercross that close as they do have flat tires… not all that often but it does happen.

    Back onto the topic at hand, I am a SRAM fan (excluding their MTB brakes) and hope they can knock this out of the park.

  20. Johnny Doe on

    @Jake- actually, SRAM isn’t the only company saying chassis stability is at play when it comes to harmonic resonance, AKA turkey warble. Some bikes do it more than others. Period. Now, instead of just having MTB frame/fork/wheel engineers neglecting to take it (chassis stability) into consideration, we are also left with road bike/component engineers neglecting the same. Now couple that with folks failing to adhere to a company’s recommended burnish procedure, by failure to read the manual or personal belief of what ‘proper burnish’ is, and you amplify the chance of said resonance building up within the bike. The brakes are just one cog within a system within a system, and the sooner all involved in the production of a modern bike get involved with it, not just the brake guys, the quieter all of our rides will be. FYI, motor vehicle companies design around this, the bike industry is just a tad behind accounting for it. One day, one day.

  21. g on

    Hey Bikerumor- On what basis do you delete comments? I appreciate that you compile news and whatnot. It’s convenient. However, you really have no credibility. Oh, and your reviews are pathetic. Thanks!

    • Kristi Benedict on

      We delete comments – or portions of a comment – that attack people, make no contribution to the conversation (such as “this sucks”), and contain profanity. We also do not tolerate sexist, racist, and other words/phrases/comments that disparage groups of people. Stay tuned, we will be posting a new comments policy soon. Note that a “First Ride” is not a “Review.”


  22. ChrisC on

    How come everyone is all pissy about the quick switch from Red to Red22 but no one bitches about the quick switch from DA 7900 to DA 9000?

  23. Ian on

    “the rotor was lightly-but-consistenty rubbing the outside brake pad on the front wheel”
    Yeah, discs going out of true, calipers getting knocked, it just seems inevitable that drag will be a regular occurrence, just as it is on MTBs. To me the advantages for an MTB outweigh the disadvantage, but when I’m racing I want to go as fast as possible, having to check disk rotors for drag sound like a PIA, not to mention far more difficult to fix than conventional road brake.
    Discs on MTBs solved so many problems, but this kind of looks more like a marketing solution than an engineering one.

  24. mateo on

    @ChrisC – The quick switch from 7900 to 9000? 7900 was top of the line for 4 years. 2012 Red was top of the line for 14 months.

  25. CXisfun on

    @Johnny Doe – Never had a bike have any turkey warble at all with Shimano SLX, XT, or XTR. I’m guessing here, but I’d say about 80% of the Avid-equipped bikes I’ve been around have it in spades. I remember Specialized blamed Avid for horrendous noises coming from a Stumpumper 29 a couple of years ago. Avid tried to blame Specialized and their dropouts. Avid’s solution was a solid rotor with no cutouts which was better, but not really all that good. I tossed on an XT brake: totally silent.

    Having worked on and built dozens of Avid bikes and at least as many SLX/XT/XTR bikes I can tell you first hand which brand I’ll put on a friends bike and which brand I wont, but I bet you can guess.

    And get this: I used to be a huge Avid fan-boy. Until I rode Shimano. Then I ate my words and went about riding in silence.

  26. g on

    Well, this sucks. Also, I understand this isn’t a review. That was more of a side note referring to the pathetic posts labeled as reviews, which really just advertise the ridiculous products that you got for free.

  27. Knuckler on

    The quick switch on Red is Sram desperately trying to stay relevant in the road sector. Did anybody care when the new group came out last year? Nope. It wasn’t a game changer and in the midst of the competition was too little too late.

  28. Matt on

    I have owned Avid, Sram and Shimano brakes. Avid/Sram have always – always been a problem. They are the worst breaks I have ever had to deal with. I am currently dealing with a brand new pair of Sram XX brakes on a new mountain bike and I am so pissed I am about to spend more money to put XTRs on so I don’t have to deal with them any more. People should wait for the Shimanos to come out. End of true story.

  29. Eddie A. on

    Maybe I err, but I can’t see any reservoir in the cut lever combo. And if it’s true that the hydraulic disc and rim brake share the exactly same lever it must not have any reservoir since the rim brake must be manually adjustable for pad wear, rim width and out of true rims. But having no reservoir on the disc brake means there has to be any other way to compensate for pad wear.

  30. chrisc on

    As with all competition i.e. SRAM verse Shimano things move foward pretty quick so we can expect disc RR components from Shimano plus their version of XX1 with no glitches,hopefully.What happens is we all benifit. Competition always improves the breed,look at the cars we drive now compared with the 1960s,thats rallying and race technoligy for you.Discs were first used at Le Man by Jag in the 50s.and made drum brakes obsolete.My first bike had no index gears you had to feel if they went in ,dont want to go back to that. In 10 years time we will be all saying ‘do you remember those old rubber brakes that wore your rims away’ or we’ll be using hover boards by then….PS i’m chrisc from the UK not ChrisC.

  31. Adam on

    I’m really looking forward to getting our hands on some of these brakes in our shop. Regardless as to people’s personal feelings about SRAM, positive or negative, it’s excellent to see big brands consistently innovating and putting new products into the market.

    My only concern is that SRAM is currently listing a 250 lb. bike + rider weight limit on the new hydraulic road disc systems. A big selling point on disc brake systems for some of our Clydesdale riders is that the disc systems offer more power and better modulation, something that a heavier rider could definitely appreciate when they feel that their standard road calipers are out-gunned on their current bikes due to their weight. I would not want to warn a customer off of buying a disc brake equipped road bike because they may run the risk of not having brakes that can handle their weight. Uber-lightweight frames and wheels I can understand; but brakes?

  32. Mindless on

    Look. All the critical comments about AVID brakes had been deleted.

    I guess with them coming out with more brakes censors on the intrawebz had been very busy.

  33. Ajax on

    Yes! Yes! YES!!!!!! OMG! Yesssssssssssssss!

    I have been waiting my whole life for a girl like you SRAM Red hydraulic disc brake! Whoever said that SRAM sucks is full of beans. I got SRAM BB7 mechanical brakes. It’s good sheeeet man! And hydraulics are gonna be even better! Truth be told, I like Shimano shifting better than SRaM o Campy, but to poo poo on SRAM brakes is just ridiculous. I am sure that Shimano is going to have as good or better hydraulic disc brakes, but sorry Shimano! SRAm beat you to my heart… and my wallet!

    Long live disc brakes!

  34. spazz on

    Ha, now the road scene will soon know what the mountain side has known for years.

    Avid hydraulic brakes are unreliable and inconsistent.

    A new phrase soon be added in the road bike community: ” I had to double-pump my brakes for that corner”

    Enjoy 🙂

  35. Rob on

    At first I was skeptical. I had massive problems with bleeding Avid XX disc brakes. They would be fine for a little while but gradually loose feel. So hearing the road version had a different slave cylinder design I am feeling quite optimistic. I’m glad I’ve deferred buying a new road bike for the last 5-6 years.

  36. Chris Hayward on

    This technology is great,but what about all the caliper braked bikes still out there,who is going to ride and maintain them in the coming years? As far as I can see the scene is set for a huge amount of unwanted and outdated road bikes as people try to jump on the technology bandwagon.


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