Interbike First Impression: Shimano hydraulic disc brakes

By Karen Brooks

Like moths to a flame, we bike geeks get drawn to the bright, shiny stuff at Interbike. Our definitions of “shiny” can vary from ultra-bling to practical-chic to clever and well-made. But it is nice, sometimes, to breathe the rarified air of the top-of-the-line. Shimano’s R785 brake and Di2 shifting systems are two such examples.

As disc brakes are becoming more common on everything from adventure touring to cyclocross to commuting bikes, and even creeping their way onto road-racing style bikes, the big two component brands, Shimano and SRAM, are paying attention. The natural next step in the evolution is to follow mountain bikes and go fully hydraulic. Aftermarket hydraulic brake systems for drop bars from TRP, Formula and others have been around for a few years, but until recently there haven’t been one-stop options. SRAM debuted the Hydro R system, for disc or rim brakes, earlier this year. Shimano fired back with the artfully named R785 hydraulic brake system that integrates with Di2 electronic shifting, and I got a chance to try out both here at Interbike.

The new brake and shifter combo is coming out at Ultegra level, so not quite top-of-the-line—that would be Dura-Ace. Makes sense, as Shimano’s first disc brake offering was at their next-to-top XT level for mountain bikes—they don’t want to present a product as the tippy-top if it isn’t yet as perfect as it could be. While the R785 brakes look and function like high-end stuff, further refinements away from mountain bike chunkiness and toward that svelte, elegant ideal of road racing will be coming in the future.

I mentioned “mountain bike chunkiness,” but that’s not a bad thing—the R785’s borrow from Shimano’s mountain bike brakes, which work very well. The rotors and pads use the same ICE-Tech heat management features as the mountain bike brakes: aluminum cooling fins on the rotors next to the steel braking surface (the rotors are made like steel-and-aluminum sandwiches), and prominent cooling fins on the brake pads. Heat buildup is the enemy of hydraulic disc brakes, and it’s more of a problem on the road where riders may be braking consistently for long periods of time at high speeds.

I tried out the combo on a beautiful Colnago C59 Disc bike. So what’s it like to ride such a fast machine? I gotta say—for this amateur rider, having powerful, well-modulated brakes makes it easier, mentally, to let the bike fly on the downhills. (Pro riders of all sorts generally try not to use their brakes much at all.) As someone who likes to use brakes, these brakes are, in a word, awesome. They have power—so much power—but it remains well-controlled. Shimano still uses a version of the classic Servo-Wave technology in their levers to make the brake pads move quickly toward the braking surface at the beginning of the lever stroke, then move more slowly, but produce more power, in the last part of the stroke. This means you can feather the brakes without them feeling “grabby,” but still clamp down and STOP on demand—although “clamp down” is not the right phrase, because the lever action is easy and butter-smooth. It also means that the pads have a good bit of clearance from the rotors, lessening those annoying “zzzzing” sounds.

The reach and free stroke of the brake levers can be adjusted with screws underneath the hood covers. The rotors come in 140mm or 160mm sizes—140mm seemed plenty big enough for me, but then again, 160mm would be nice to have for some loaded touring.

This was my first real try of Shimano’s Di2 electronic shifters. I was more skeptical of this technology—what if it rains? What if the battery runs out? But again, I was impressed. The front shifter works phenomenally well—instant and effortless. The rear shifting is equally smooth and quiet, but I suppose I could argue that I prefer the manual feel that allows for downshifting by several gears at a time. It hardly rains in Las Vegas so I can’t yet answer the first question, but Shimano says the battery will last 600 to 1,500 miles between recharges, which is not bad at all.

The R785 / Ultegra Di2 system will be available in November or December. As you might guess, it won’t be cheap. Shimano didn’t yet release individual prices, but bikes spec’d with these systems will be in the $4,500 – $7,500 retail range. One can dream…


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