Hands-On With Shimano’s New Di2 Hydraulic R785 Road Components

Shimano R785 Road Hydraulic Di2 STIWe recently received Shimano’s new R785 Di2 hydraulic road components and took a moment to photograph the new hardware. Above is the new R785 Di2 shifter with a hydraulic brake master cylinder tucked inside. This is really cool, and everyone is excited over the marriage of flawless Di2 shifting with Shimano’s highly refined hydraulic braking.

So far, these components are non-series specific. They don’t bear the Ultegra or Dura Ace moniker like most of Shimano’s road groups, however the “785” model name seem to indicate XT and Ultegra level components respectively.Shimano R785 Hydraulic Di2 Road STI  Button BacksideHidden behind the brake blade are the Di2 electronics, compact enough to be housed inside the relatively tiny housing pictured above. Integrating Shimano’s new hydraulic braking into a Di2 STI body allowed Shimano more room for the hydraulic master cylinder given the absence of mechanical shifting hardware which is normally built inside of the STI body and not behind the brake blade.

However, Di2 isn’t the big news today. Keep scrolling down to familiarize yourself with the hydraulic half of these new R785 components.


The Hoods

Peeling back the hoods is simple. Six plugs molded on the inside of the hoods, three on each side, plug into the STI body. We found the hoods can be a little difficult to properly secure to the body. A little bit of pressing and twisting of the hood eventually led to a secure and clean hood install.


Removing The Faceplate

This is simple and the first step to accessing the bleed port. You need a small flat head screwdriver to remove one tiny screw. After you lose the screw in your shag carpet or dirty garage floor, the faceplate lifts up and off beginning just above the brake blade.


The Bleed Port

Found right on top of the body is a small black round screw. This part is pretty basic – uses a 2.5mm allen wrench and has a rubber o-ring.


Shimano Bleed Tool Compatible

Keeping things as easy as possible you can attach Shimano’s bleed tool to the top of the lever. Pull the plug from the bleed tool to send fluid pouring into the master cylinder and begin bleeding, adding fluid before the cup is empty.


The Brake Caliper

Shimano R785 Hydraulic Di2 Road Brake Caliper Kit


Look familiar? These appear to be very similar to Shimano XT but with a different finish. Presumably the internals are modified to work optimally with the master cylinder housed inside the STI body.


Pad Installation

The pads install the same way as their mountain calipers. The pads have their own return spring and are top loading with a threaded cross pin, then finished off with a safety clip.


Attaching The Banjo Fitting

The system comes disassembled allowing you to run the hoses internally if needed and cut to fit as necessary. On the Lever end of the hose are an olive and barb, the brake end having an adjustable angle banjo fitting. The caliper ships with a throw-away silver phillips head screw, preventing contamination of the piston cylinders. Remove that and attach the banjo fitting in the desired angle with the included hardware and you’re set.


Ice Tech Freeza Rotor

Shimano recommends a 140mm Freeza rotor for all road applications regardless of weight or conditions. They state the finned pads matched with Freeza finned rotors in conjunction with Ice Tech’s aluminum-steel-aluminum layering technology means the 140mm rotors won’t overheat and will provide plenty of power and allow for proper modulation.


Feel free to contact us if you’re interested in including this new kit with your upcoming build, or are looking to upgrade your current bike. There are definitely a few considerations and nuances to road disc ranging from hub spacing to disc compatible road forks with fender mounts.

Also, we have several bikes slated to receive these components so stay tuned for some custom bike photo shoots!

Posted by on January 10th 2014