Shimano Launches Hydraulic Road Disc Brakes

Disc Parts

Shimano’s new hydraulic disc brake system uses the same technology found on its popular mountain bike brakes.

The hydraulic road disc brake system war is officially on. Just a few months after rival component maker SRAM came to market with its Red 22 hydro disc brake offering, Japanese giant Shimano has jumped into the game — as long as you are also running one of its electronic shifting groups.

Indeed, the new braking technology (called R785) is a melding of existing Di2 electronic shifting with Shimano’s ICE Technologies hydraulic disc brake heat management system that is well-known in the mountain bike world. The R785 groups is actually not a group, just an Ultegra-level Di2 shifter, caliper and rotor that are cross-compatible with any E-tube equipped Di2 group, be it Dura Ace 9070, 10-speed Ultegra 6770, or the new 11-speed Ultegra 6870, which was also unveiled this week (more on that later).

Pricing for the new disc brake components has yet to be released and the system wont be available until sometime in November, though we’d be surprised if it doesn’t show up as spec on 2014 model year bikes hitting shop room floors earlier in the fall.

Perhaps the biggest initial take-away is Shimano’s unblinking confidence in its new braking system. While SRAM is recommending 160mm rotors for paved use and 140mm for cyclocross with its system, Shimano says 140mm will work in all applications — and for all rider weights.

“As long as you are using our ICE-Tech rotors and pads, we are confident in the 140mm recommendation,” said Shimano road product manager Dave Lawrence, adding that there will also be a 160mm option for those who prefer a larger rotor size.

The ICE-Tech rotor is claimed to provide superior stopping power in all conditions.

The R785 rotors are essentially identical to the recently launched XTR brake rotors, and include the fin-shaped brake pads Shimano claims can reduce heat build-up by upwards of 50 degrees, a number that increases a further 150 degrees when you add Shimano’s RT99 rotor and contrast that against a standard steel rotor. Those ICE-Tech rotors have what Shimano calls FREEZA fins, which add surface area without increasing rotor size. Dual-piston calipers further increase braking power.

Troubling to some will be the fact that the new RT99 rotors are centerlock only. Perhaps not coincidentally Shimano also launched a new road disc wheelset (WH-RX31) that has no rim brake track, and accommodates 140mm and 160mm centerlock rotors.

The other big takeaway is weight – as in added weight. Lawrence estimates that running disc brakes will include “about a 300-gram” weight penalty and our math puts it more in the 330-340 range. It’s for this reason that, while a huge fan of the technology, even Lawrence admits that traditional rim braking systems aren’t yet in danger of rapid extinction.

“I think at least for now, there will still be a lot of people that want to stay with rim brakes,” said Lawrence. “Even for me it’s a tough call. We don’t get a lot of rain out here, which is where you see some of the biggest benefit from a braking standpoint (when using disc). Plus our rim brakes obviously work very well and I am very confident using them. But on those rainy days, I jump on my disc-brake-equipped bike when I’m riding into work and feel a lot more confident.”

The other perhaps more immediate application will be in cyclocross. Already last year, disc brakes became a common sight at top-level UCI races in the U.S., and Lawrence suspects adoption by top World Cup level riders will happen as soon as the weight penalty is wiped out.

“Anyone who has ridden disc for ’cross understands how much more control you have,” said Lawrence, alluding to the fact that you can brake later in corners with more power and better modulation. “That is something that is definitely confidence inspiring. But if you look back to the transition from V-brakes to disc brakes in top level mountain bike racing, the tipping point only came when there wasn’t a weight penalty anymore. That’s why it may take a little more time. I also think it goes hand in hand with frame development. These first generation road and cross frames that are disc compatible have some weight penalty, as well. But as the technology evolves and understanding increases, we’ll see fuller adoption. It’s one of those things that you really have to get people on it. Then they understand.”

As for the new R785 shift levers, they offer the full menu of E-tube compatible shift options, including Shimano’s sprint and climbing shifters along with the ability to adjust shift speed and shift count. Firmware updates will allow for upgrades over time.

Finally it’s worth noting that Shimano’s disc brake system utilizes the same hose fittings and bleed techniques as its current mountain bike hydraulic systems, which means there wont be as big a learning curve for shops or home mechanics. “Even most of the small parts carry over from mountain biking to the road system,” noted Lawrence.

Oh yeah, Shimano also unveiled its new 11-speed Ultegra 6970 electronic shifting system.

Somewhat overshadowed in all this is the new 11-speed Ultegra Di2 6870, which adds a gear, drops a net of 126 grams if you opt for an internal battery, and now includes a mid-cage derailleur option that will accommodate a 32-tooth rear cog, something Di2 has never had before. Up front, the new Ultegra 6800 crank, which we’ve already seen this year, features the four-arm spider and interchangeable chain rings that make it possibile to run 53-39, 52-36, 50-34, and now 46-36 gearing for cyclocross.

Pricing for the new Ultegra 6870 group is not yet available. And like the new disc system, it’s slated to hit stores in November. You can learn all about those enhancements and more in the extensive photo gallery below.

Shimano Launches Hydraulic Road Disc Brakes Gallery
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    Lots Of Improvements

    The new Ultegra shift/brake lever is claimed to have improved hood ergonomics for easier access to the shift buttons. New E- Tube wiring is also cleaner, simplifying the addition of satellite shifters to bar tops while also being multi-shift program ready.
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    New 11-Speed Ultegra 6870

    The revamped group features an extra gear and a net weight loss of 126 grams from its predecessor if you use an internal battery. Claimed weights for the entire group are 2,359 grams with an internal battery and 2,416 is you opt for external.
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    Another Look

    The new Ultegra ST-6870 brake lever, claimed weight 295 grams, 18 grams lighter than the ST-6770 lever.
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    Fastman Friendly

    Like the Dura Ace ST-9070, the new Ultegra ST- 6870, has a 3rd port for the use with the SW-R610 Sprinter shifters.
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    Grams Dropper

    The new Ultegra front derailleur is 12 grams lighter than the 6770 version.
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    Slim and Trim

    The new FD-6870 front derailleur maintains automatic trimming function and... (see next photo).
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    Lighter and Wider

    The new Ultegra derailleur sheds 20 grams from 250 to 270, and can now comes in a mid-cage GS version that accommodates up to a 32-tooth cog.
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    Straight and True

    The new re-designed FD-6870 front derailleur features a support bolt that creates a rigid platform and keeps correct alignment while moving the chain to the big chain ring.
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    Another Look

    The new RD-6870 rear derailleur.
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    For the Tri Crowd

    The new group includes a two-button TT/Tri shifter set with built-in E-tube wires.
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    Tag Team

    The combination of rotor and caliper works so well, Shimano says 140mm rotors will work just fine for road use. But you can upgrade to 160mm if you prefer.
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    Little Changed

    Unlike the hydro disc shifter from SRAM, Shimano's new hydraulic lever did not see a big increase in height. Yet it still delivers more stopping power with less effort, especially from the hood position.
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    Pleasing To The Touch

    The new ST-R785 hydraulic/shift lever is highly ergonomic to accommodate a variety of hand sizes. Claimed weight is 515 grams, which is 220 grams heavier than it's new Ultegra 6870 cousin.
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    Icy Cold

    Shimano claims the new SM-RT99 Center-Lock finned disc brake rotors reduce braking heat by a whopping 150 degrees compared to steel disc rotors.
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    Lockdown

    The new RT99 rotors are centerlock only. And not coincidentally Shimano launched a new road disc wheelset (WH-RX31) that has no rim brake track, and accommodates 140mm and 160mm centerlock rotors.
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    Hard Stop

    The new BR-R785 hydraulic disc brake caliper features a two-piston design that's claimed to provide the same stopping power as its mountain bike brethren.
About the author: Jason Sumner

An avid cyclist, Jason Sumner has been writing about two-wheeled pursuits of all kinds since 1999. He’s covered the Tour de France, the Olympic Games, and dozens of other international cycling events. He also likes to throw himself into the fray, penning first-person accounts of cycling adventures in British Columbia, Belgium, Brazil, Costa Rica, France, and Peru among many others. Sumner, who joined the RoadBikeReview.com / Mtbr.com staff in January, 2013, has also done extensive gear testing and edited a book on cycling tips. When not writing or riding, the native Coloradoan can be found enjoying the great outdoors with his wife Lisa.


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  • Bryan girton says:

    My last set of mtb brakes I bought was a set of shimano’s with the ice tech rotors. It’s too early to comment but they may be the best yet.

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