Canyon Endurace: Dura-Ace R9170 Hydraulic Brake Calipers and Rotors

With the new Dura-Ace groupset, it now includes road hydraulic disc brakes, and has its own series of hydraulic disc brake calipers and rotors. For Dura-Ace, the focus is on providing lightweight, high performance, race ready components. After checking out the ST-R9170 Di2 shifter with hydraulic brakes, let's take a look at the brake calipers and also the brake rotors in this post.

The new mounting standard for road disc brake calipers is the Flat Mount standard, which puts the brake calipers closer to the frame for a neater look. As such, the brake calipers look quite different from traditional MTB style brake calipers, such as the BR-RS785 brake calipers used on the Avanti Inc 3.

Dura-Ace Flat Mount hydraulic disc brake calipers

BR-R9170 is the model number of this Dura-Ace brake caliper

Yellow block in between the pistons are for bleeding the brake caliper. The brake pads will be installed later on.

The front and rear brake calipers are actually the same, but the hardware that is supplied is different due to the different mounting methods for the front and rear.

For the front brake caliper, it has an overall weight of 136 grams when installed on the bike. See how many loose parts there are!

The front brake caliper requires an adapter for running with either 140mm or 160mm disc rotors. What is clever is that this adapter can simply be reversed to achieve either sizes.

Flipping the adapter to the other side will move the caliper position upwards, to make it suitable for the larger sized 160mm rotor.

When used for 140mm rotor, the brake caliper will be situated lower on the front fork to match the smaller rotor diameter.

When used for 160mm rotor, the brake caliper is located higher up on the front fork.

Hardware that comes with the rear brake caliper. Still quite a lot of loose parts that need to be assembled. Weighs 126 grams in total.

Two long bolts for securing the brake caliper to the left side chain stay, along with a safety pin to prevent the bolt from dropping out completely if it happens to loosen.

For the rear, an additional adapter is needed if 160mm rotors are used. Else the brake caliper can just be bolted directly to the frame for 140mm rotors. In my case, I will just use the original adapter that came with the bike, which has a stock rotor size of 160mm.

New brake pad design that is used for the Flat Mount disc brakes. It has a slightly smaller pad area as compared to normal brake pads.

Brake hose bolts, olives and connecting inserts for use with BH90 hydraulic brake hose. I had to obtain these separately as they are not included if you order the shifters and brake calipers separately.

Other than the new Dura-Ace brake calipers, there are also new Dura-Ace disc rotors! These new rotors have a unique appearance unlike no other disc rotor.

Dura-Ace grade disc rotors, SM-RT900

4 arm aluminium spider, together with the gigantic black cooling fins that takes up the rest of the space within the rotor.

S size refers to 160mm diameter. SS is for 140mm.

As shown here, it has a diameter of 160mm

Ice-Tech design with the logo printed on the rotor

Some unevenness of the black colour at the edges, only noticeable if you look closely

Slightly chamfered edges, which supposedly makes it safer

Weighs 118 grams each for the 160mm size, without lock rings.

Very premium looking lockring, befitting of the Dura-Ace grade rotor

Lockring is very lightweight at only 7 grams each

Each set of rotor plus lockring is thus 125 grams, which is a decent weight. One bike's worth of rotors would thus be 250 grams.

As for the hydraulic brake calipers, one pair of brake calipers would be 262 grams. Overall, the disc brake calipers and rotors would add 512 grams to a bike.

R9150 Di2 Shifter with mechanical brake + R9100 mechanical brake calipers: 226 + 321 = 547 grams
R9170 Di2 Shifter with hydraulic disc brake + R9170 hydraulic brake calipers and rotors: 320 + 512 = 832 grams

Between the hydraulic and mechanical brake version, the hydraulic version adds about 300 grams to the overall system. This is assuming that all other components are the same.

Shimano Road Hydraulic Disc Brake Di2 Shifters: ST-R9170 vs ST-R785

After comparing the mechanical shifting versions, I will now compare the Di2 versions of the road hydraulic shifters. The non series, first generation, Di2 shifter with hydraulic braking is the ST-R785, while the latest second generation is the Dura-Ace ST-R9170.

For Dura-Ace components, being lightweight is very important. Having the best function is also required. In this case, the shifter was totally redesigned to create the new ST-R9170, as compared to the ST-R785.

New Dura-Ace ST-R9170 weighs only 160 grams per side, giving a total weight of just 320 grams per pair.

Non series ST-R785 weighs 254 grams per side, giving a total of 508 grams per pair, which is significantly heavier.

Rubber hood has a different texture, with the "waffle" pattern used on the new ST-R9170 (right side).

Comparing the side profile, the ST-R9170 is obviously lower in height, which makes it look much more similar in shape and size to the other Dura-Ace road shifters.

Dura-Ace ST-R9170 is lower in height, while the lever shape is also curved outwards to match the other mechanical road shifters.

ST-R9170 on the left looks very similar to other road shifters, while ST-R785 has a large silver cover which gives it a very distinctive look.

ST-R9170 on the left has slightly larger Di2 buttons and a stronger click feeling, for an improved tactile feel.

Rear of the lever is where the mechanism for the buttons are housed. ST-R9170 on the right has a cleaner look as the parts are all black in colour and more concealed.

ST-R785 on the left has a lever stopper on the Bracket, while the wire can also be seen. ST-R9170 improves on these with a reach adjustment bolt at the bottom and hides the wire, while the rubber hood texture has also been changed.

Rear view shows that the new ST-R9170 (right side) has a wider Bracket, and uses a titanium Clamp Band for lighter weight.

Internal profile of the ST-R9170 rubber hood. Due to the multiple protrusions as shown, and the many ribs on the Bracket, it was very difficult to remove and install the rubber hood.

ST-R9170 on the left has many ribs on the resin Bracket for weight savings, while ST-R785 on the right uses an aluminium Bracket.

The Di2 unit is smaller in size on the ST-R9170 (left side), while it is also located more rearwards for easier access. Also note the different wire routing through the Bracket.

Another major difference is the pivot location of the brake lever. ST-R785 on the left has a high pivot, while ST-R9170 has a pivot location that is lower and similar to other mechanical or Di2 road shifters. This allows the brake lever ergonomics to be similar to other Dura-Ace shifters.

The bleeding port for ST-R9170 (left side) is located in the middle of the Bracket (black bolt), while the ST-R785 bleeding port is right at the front of the Bracket. The little bump at the front of the ST-R9170 bracket is the top button which can be programmed.

This side by side picture shows how different the Bracket design is, as well as the different hydraulic design.

This new generation ST-R9170 is a significant improvement over the first generation ST-R785, with the major improvements being lower weight, smaller size, and a more conventional braking ergonomics. There is also an additional button on top for extra customization.

Shimano Road Hydraulic Disc Brake Mechanical Shifters: ST-R9120 vs ST-RS685

There has been two generations of road hydraulic shifters, with the first being non series, and the latest being part of the Dura-Ace series. For the mechanical shifting version, the first generation ST-RS685 is now used on many cyclocross bikes or road hydraulic disc bikes. The improved, second generation version is the Dura-Ace ST-R9120 which is engineered to be more lightweight.

ST-RS685 weighs 324 grams per side, giving a weight of 648 grams per pair. This is heavy, mainly due to the aluminium Bracket.

ST-R9120 is lighter in weight, weighing 265 grams per side, for a total weight of 530 grams per pair.

Release lever of ST-R9120 on the right has been slightly increased in size for easier activation.

ST-RS685 on the left is non series, with the Shimano logo on the lever. The new ST-R9120 on the right has the Dura-Ace logo, with a superior surface finishing.

View from the front shows that the curve of the lever is similar, but the ST-R9120 has a slightly wider lever shape near the top.

The hood shape is slightly different, with ST-R9120 at the front having a more rounded hood that is slightly lower in height.

From the front, the difference is obvious. ST-R9120 on the right is lower in height but slightly wider, which gives the impression of a smaller hood size.

Inside view of the Bracket. ST-R9120 on the right uses a resin Bracket, and you can see the cylindrical shape of the hydraulic system.

Rear view of the shifters show that the ST-R9120 on the left is slightly wider in size but also shorter in height.

Upon removing the rubber hoods, more differences can be seen. ST-RS685 on the left has an aluminium Bracket, while ST-R9120 on the right has a resin Bracket.

View from the other side. ST-RS685 uses metal pipes for the hydraulic system, while ST-R9120 on the right does not.

From the top, we can see that the new ST-R9120 on the right has the piping concealed within the resin Bracket, instead of being separately created via metal pipes.

ST-R9120 on the left has a different thread size, which is M9x1.25. This is different from the standard M8x0.75 that is used on other most Shimano brakes.

Main difference between these two shifters is the material used for the Bracket, which directly affects the weight. The hydraulic design has also been tweaked to eliminate the need for metal piping, and instead route the hydraulic fluid within the resin Bracket itself. All these improvements lead to weight savings and also a smaller overall size.