Persistent brake noise can be both frustrating and alarming for road cyclists, particularly when it’s coming from a component as reliable as the Shimano BR-6700 [paid link]. As part of the Ultegra series, the BR-6700 [paid link] caliper brakes are known for their consistent modulation, clean design, and superior stopping power. However, like any high-performance component, they demand correct installation, precise alignment, and ongoing maintenance. When these factors aren’t met, squealing, rubbing, or grinding noises may develop. This article focuses exclusively on diagnosing and eliminating noisy braking issues specific to the Shimano BR-6700 [paid link].
Understanding the Source of Brake Noise
Noisy braking on the BR-6700 is typically a symptom of underlying mechanical or environmental issues rather than a fault with the calipers themselves. Causes can range from simple pad contamination to misaligned components or improper cable tension. Understanding the exact nature of the noise—when it occurs and under what conditions—is crucial to pinpointing the cause.
For example, a high-pitched squeal under light braking typically indicates pad-to-rim contamination or improper toe-in, while a grinding sound suggests debris lodged between the brake pad and the rim. Each symptom corresponds with a specific issue and correction method, which we’ll cover in the sections below.
Common Causes of Noise in BR-6700 Brakes
Pad Contamination and Material Transfer
Contaminated brake pads are the most frequent cause of noise in the BR-6700. This model uses cartridge-style pads that are replaceable and sensitive to oil, grease, and even some cleaning sprays. If the pads absorb contaminants, they produce a tell-tale squeal during braking.
Material buildup—where brake pad residue transfers to the rim—can also create a glassy surface that resonates under pressure. The result is often a vibrating, loud braking experience, especially at slower speeds.
Incorrect Pad Alignment
Shimano’s BR-6700 calipers allow for micro-adjustment of pad angle. If the pads are not aligned properly with the braking surface—either too high, too low, or lacking appropriate toe-in—they can cause inconsistent contact with the rim. This misalignment leads to noise and reduced braking efficiency. Toe-in, where the front of the pad contacts the rim slightly before the rear, is particularly important to eliminate noise.
Rim Surface Condition
The BR-6700 performs optimally with clean, machined alloy rims. Dirty, oxidized, or worn braking surfaces disrupt pad engagement, causing squealing or groaning noises. Additionally, carbon rims—although less common for riders using BR-6700—require specific pads. Using the wrong pad-rim combination will always result in poor performance and noise.
Cable Tension and Caliper Centering
Uneven brake pad pressure due to unbalanced cable tension or miscentered calipers can cause one pad to contact the rim prematurely. This asymmetry results in brake rub and often creates noise during rotation or initial brake application. It may also compromise modulation.
Environmental Factors
Humidity, road debris, and cold temperatures can temporarily affect the performance of the BR-6700 calipers. For instance, moisture on the braking surface reduces friction, often resulting in a squeaky, slipping sound until the system heats up and dries out.
Diagnosing the Noise: A Step-by-Step Approach
Diagnosing noise in the BR-6700 brake system involves a systematic inspection:
- Visual Pad Check: Examine the brake pads for embedded grit, uneven wear, or a glossy glaze. Check that the wear indicators haven’t reached their limit.
- Pad Alignment Review: Observe the contact patch. Pads should align with the rim braking surface and show a slight toe-in. No part of the pad should touch the tire or dip below the rim.
- Rim Surface Inspection: Clean the rim with isopropyl alcohol and a clean rag. Look for oil streaks, discoloration, or grooves that may indicate embedded debris.
- Caliper Centering Test: Squeeze the brake lever and watch the pads approach the rim. Both sides should move symmetrically. If one moves earlier or faster, recenter the caliper using the centering screw.
- Cable and Housing Inspection: Look for frayed or corroded cables. Ensure the housing isn’t pinched or cracked, which can affect tension and responsiveness.
Fixing the Noise: Specific Solutions for the BR-6700
Cleaning and Decontaminating
Remove the brake pads and clean both the pads and rims with rubbing alcohol. Use a fine grit sandpaper (around 120–150 grit) to lightly scuff the pad surface if glazing is present. This removes hardened material and restores grip.
Pad Realignment
Loosen the pad bolt, reposition the pad for full rim contact, and adjust the toe-in. A standard guideline is a 1–2 mm offset, where the front edge of the pad touches the rim first. This prevents harmonic vibrations that cause squealing.
Brake Caliper Centering
Use a Phillips screwdriver to adjust the centering screw located on the top of the BR-6700 caliper arm. Turning it clockwise moves the left arm inward, and counterclockwise shifts the right. Aim for symmetrical pad movement and balanced rim contact.
Cable Lubrication and Tensioning
Apply a small amount of cable-specific lubricant to reduce internal friction. Then, adjust the barrel adjuster at the lever or caliper to fine-tune cable tension. The goal is a firm lever feel without excessive free-play.
Rim Maintenance
Use a dedicated rim cleaning pad or a light abrasive tool to remove embedded grime and restore the rim’s braking surface. This is especially important if you regularly ride in wet or gritty environments.
When Replacement Is Necessary
If pads are excessively worn or contaminated beyond cleaning, replace them with Shimano-compatible cartridges. Ensure the replacement pads match your rim type. Carbon rims require specialized compounds not included with stock BR-6700 brakes.
Preventive Measures for Quiet Braking
Routine maintenance is key to noise-free operation. Clean your braking surfaces weekly if riding in urban or wet areas. Check pad alignment monthly, and inspect cable tension during seasonal tune-ups. Applying these small measures consistently will preserve the BR-6700’s reputation for quiet, dependable braking.
Conclusion
Noisy braking on Shimano’s BR-6700 calipers is not a sign of product failure—it’s a signal that some element of the system needs attention. From pad contamination and alignment to rim condition and caliper centering, each factor plays a role in maintaining optimal performance. With precise adjustments and regular care, you can ensure that your BR-6700 brakes remain silent, powerful, and reliable mile after mile.