Welcome to our Ask a Mechanic column where our expert mechanic Daniel Slusser answers your bike maintenance questions. If you have a question for Daniel, please post it on our Facebook Wall or e-mail Daniel directly at firstname.lastname@example.org. Today’s column will review how to adjust road brakes and get rid of that pesky squeal that sometimes crops up.
I just put a new pair of HED Ardennes FR wheels on my BMC Race Machine and now I am getting a squealing sound coming from the front brake. I have an Ultegra brake with the stock brake pads. The old wheels didn’t do this and the brake is centered on the rim, so I am not sure what I need to do to fix it. Some guys talk about “towing” in their pads… is this what I need to do? How do you do that? From: Casey
Congratulations on the new wheels. I think you will love them once this little proverbial fly is removed from the ointment. Because your Ardennes wheels are about 4 millimeters wider than the stock wheels, your brake pads are probably not lining up properly. It is an easy fix however.
The first step is to adjust the cable tension. I would start by dialing the brake barrel adjuster all the way in so that the brake is as wide as possible and then turn it back out about 4 clicks. This will let you more easily fine tune the brakes later. Next, release the cable anchor by backing out the 5mm head bolt that is clamping down on the cable. Once the cable is released, use your hands to squeeze the brake down to the width that you want it to be with the brake in the closed position. Once you have the brake at the proper width, tighten down the cable anchor again to hold the brake in the correct starting position.
The next step is to get your brake pads adjusted. Pull the brake lever and hold it so that the brake is clamped down on the rim. Then use a 4mm allen wrench to release one of the brake pads. After releasing it you should position the pad where you want it with one hand while pulling the brake lever with the other hand once you get the pad in the right spot. Now, without letting go of the brake lever, use your 4mm allen to tighten the brake pad back down to anchor it in place. Repeat this procedure with the pad on the other side of the wheel. Then just use your brake’s barrel adjuster to fine tune the feel.
This procedure will put your brake pads in a neutral position. For 95% of bikes this will result in quiet running, powerful brakes and with the quality of the bike and components you are using, I am supremely confident that this will solve your problem. Sometimes however, due to different braking surfaces and frame, fork, and brake stiffness variations, a squeal will still be present. This is when you want to “toe-in” your brakes. What this means is that you adjust the brakes so that the leading edge of brake pad contacts the rim first. Such an adjustment helps to compensate for the flex in the brake that occurs when once the pads start to grab onto the rim, pulling them forward and angling the leading edge away from the rim.
“Toeing-in” a brake can be done by eyeballing where the pad needs to be and can be accomplished by simply holding the pad where you want it and then tightening down the 4mm brake pad bolt to hold it in place. However, a more consistent method is to employ a business card as a spacer that is placed between the rim and the trailing edge of the pad. The next step is to repeat the procedure outlined above where the brake lever is pulled, the card is clamped between the rim and pad, the pad anchor bolt is released and then tightened down again with the pad in the new position, before releasing the brake lever again. You may need to use a doubled over business card to get enough “toe-in” to eliminate your squeal.
If all of this fails, the last resort is to try a “negative toe” or “toe-out” which is simply the opposite of the “toe-in.” In this type of adjustment the brake pad leading edge is spaced out from the rim. A “toe-out” position is almost never the solution and I discourage it in all but the most severe cases because it results in such uneven pad wear and significant reduction in braking power.
One other thing you should check for is metal in your brake pads. Inspect the face of the pad to see if there is metal that has separated from the rim and embedded itself in the pad material. Use a sharpened spoke or screwdriver to pry it out or replace the brake pad.
With any luck this post has motivated you to dip your “toe” into the icy waters of brake adjustment and has cured you and your brakes of any unwanted squealing. Ride in peace Casey!
Daniel Slusser is a professional bicycle mechanic with over ten years of experience. He holds a bachelor’s degree in business administration from HSU and a master’s degree in history from Cal Poly University. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.