Ask a Mechanic | Shimano Direct Mount Brake Setup

Question: Could you please show how to set up and adjust Shimano direct mount brakes? From: Panicos

Answer: This style of brake is increasingly popular with frame designers because it works so well with aero road and TT bikes. Shimano’s direct mount brakes use a different, more involved setup procedure than their traditionally mounted SLR-EV brakes, but they aren’t too difficult to dial in.

Before you get started it’s worth noting a few limitations that these brakes have. Rim widths should be between 21 and 28mm. For rims with 24-28mm widths, Shimano’s thinner R55C4-1 pads need to be used. On the Dura Ace 9010 brake, Shimano’s max recommended tire width is 25c, but with the Ultegra 6810 and 105 5810 brakes you can go all the way up to a 28c max tire width.

One curve ball that you have to deal with on this brake installation is that the rear brake is different than the front brake. A key difference between them is that the rear brake uses Shimano’s CB90 inline brake quick release to open and close the brake as well as handle cable tension adjustment.

Set your cable length for both the front an rear brakes just like you would on a traditional brake and avoid any unnecessary bends, while also ensuring that the housing isn’t stretched too far when the brake is pulled.

Put the CB90 on the rear brake cable just far enough away from the stem so that it won’t bounce up and hit the stem, but not so far away from the stem that the CB90 hits your frame’s headtube when the handlebars are turned. Cut out a section of the cable housing that is about 5mm narrower than the overall width of the CB90 before installing it.

Now you can run your inner wires and get them clamped down to the caliper. For the front brake, use your hand to push the pads against the rim while you lightly tighten down the cable anchor bolt. Apply final torque with a torque wrench set to 6 to 8nm.

For the rear brake, you need to start by opening the CB90 to properly set cable tension unless you have a fourth hand tool. This little trick helps to get the cable tension in the right ballpark in spite of the curved cable routing. Torque the cable fixing bolt to 6-8nm.

Close the CB90 and check your cable tension by squeezing the brake a few times. This also helps to seat the cable housing into the brake and frame housing stops. Use the barrel adjuster on the CB90 to get the cable tension close to where you want it. Backing out the barrel adjuster will increase cable tension to make the brake feel firmer. On the front brake, use the caliper’s built in barrel adjuster. Cut the excess cable so that about 25mm is extending past the clamp and then install your cable end cap.

Now we can position the brake pads. Pull the brake lever and then use a 4mm Allen wrench to loosen the pad fixing bolt on one side. Reposition the pad so that it is centered on the rim’s brake track and then pull the brake lever and hold it while you tighten down the brake pad fixing bolt. Repeat this on the other side of the brake.

Now use a 2mm Allen wrench to adjust the brake’s centering bolt. This bolt is in a slightly different spot for the front and rear brakes. On the front brake it can be found here, and on the rear brake, it is found here. Use this adjustment to make sure that the rim isn’t pushed to one side when applying the brakes.

Next we’ll toe-in the pads. Place a business card folded in half between the trailing edge of the brake pad and the rim. Pull the brake lever and hold it before you loosen the brake pad fixing bolt and then tighten it right back down again. Torque the pad fixing bolt to between 5 and 7nm. Repeat this process on the other side of the brake.

Dura Ace 9010 direct mount brakes feature a caliper spring tension adjustment bolt that isn’t found on Shimano’s traditional road brakes. On the front brake the bolt is located here, and on the rear brake, it can be found here. Adjust spring tension with a 2mm Allen to control the feel of the brake. I prefer as little spring tension as possible for a lighter brake feel with more sensitive modulation. Rotating the bolt clockwise increases spring tension for a firmer lever feel, while turning it counter-clockwise produces a lighter lever feel.

Ultegra 6810 and 105 5810 brakes require removing the brake from the bike in order to adjust the spring tension into one of two spring tension positions. It’s a bit of a hassle and you probably won’t need to adjust this, but here’s how you do it. With the brake off of the bike, you’ll need to install the brake installation spacing tool and spring. Then back off the brake centering bolt before using a pair of needle nose pliers to remove the upper eye of the coil spring from its mounting perch so that it can be placed on the other optional mounting perch.

Reinstall the brake being sure to remove the installation tool once you get the bolts started. Then torque the mounting bolts to between 5 and 7nm and readjust your caliper centering adjustment screw.

We’re almost done. Lastly, dial in your barrel adjuster to get the feel you want at the lever. If you can’t get the feel you are after using the barrel adjuster, readjust your cable tension at the cable anchor bolt and you’re done.

2015-12-16T14:38:25-08:00