Common Shimano Brake Issues: Troubleshooting and Fixes
Common Shimano Brake Issues: Troubleshooting and Fixes
Introduction: Common Shimano Brake Problems
Shimano disc brakes are a trusted choice for cyclists, but even the best brakes can encounter issues. This guide covers the most common Shimano brake problems, their causes, and fixes. Whether you're dealing with squealing brakes, spongy levers, or rotor rub, we've got you covered with expert tips and tools.
1. Why Are My Shimano Brakes Squealing?
Symptoms:
- High-pitched noise during braking.
- Reduced braking power.
Causes:
- Contaminated rotors or brake pads.
- Improper bedding-in of pads.
- Glazed brake pads from overheating.
- Air in the Shimano brakes.
- Leaking seals.
- Corrosion.
- Wandering bite point.
Fixes:
- Clean the rotors and pads using isopropyl alcohol.
- Sand glazed pads lightly with fine-grit sandpaper.
- Re-bed the pads by performing several controlled stops from moderate speed.
Upgrade your brake pads with Shimano Factory Racing Compounds or Shimano Enduro Pro Compounds for quieter performance.
2. What Causes Spongy Shimano Brake Levers?
Symptoms:
- Brake lever feels soft or spongy.
- Ineffective braking.
Causes:
- Air in the hydraulic system.
- Low or old hydraulic brake fluid.
Fixes:
- Bleed your brakes to remove air bubbles.
- Refill or replace the brake fluid using a bleed kit.
Get the Shimano Workshop Bleed Kit for an efficient bleeding process. Other Shimano Brakes bleed options
3. How to Fix Rotor Rub on Shimano Brakes
Symptoms:
- A rubbing sound when spinning the wheel.
- Resistance in the wheel rotation.
Causes:
- Misaligned brake caliper.
- Warped or bent rotor.
Fixes:
- Check and realign the caliper if necessary.
- Use a rotor truing tool to fix minor bends.
Keep your rotors aligned with the Park Tool DT-2 Rotor Truing Fork.
4. Troubleshooting Sticky Brake Pistons
Symptoms:
- Brakes fail to release after pulling the lever.
- Uneven pad wear.
Causes:
- Dirt or debris around the pistons.
- Lack of lubrication or old fluid.
Fixes:
- Clean the pistons with isopropyl alcohol.
- Push the pistons back into the caliper using a brake piston press.
Tools for this job: Park Tool PP-1.2 Hydraulic Brake Piston Press and Park Tool PS-1 Disc Brake Pad Spreader.
5. Replacing Worn Shimano Rotors and Pads
Symptoms:
- Decreased stopping power.
- Grinding noise during braking.
Causes:
- Worn-out rotors or brake pads.
Fixes:
- Replace the rotors if they are below the recommended thickness.
- Install new brake pads for consistent performance.
Shop high-quality Disc Brake Rotors for better durability and stopping power.
Tools and Products for Shimano Brake Maintenance
To maintain and repair your Shimano brakes effectively, equip yourself with these essentials:
2 comments
Hi Charlie,
Thanks for the detailed breakdown — that’s definitely a frustrating run of issues, especially with such a high-end setup like Saint.
From what you’ve described, it sounds like you’ve experienced a mix of heat-related pad glazing, possible fluid contamination, and maybe even lever/piston inconsistencies. Shimano Saints are usually very reliable, but they can be less forgiving than other systems when something’s slightly off — especially after air travel or inconsistent servicing.
🔧 What Might Be Going On:
• Pad contamination can be sneaky — even a small amount of DOT or mineral oil (or bike cleaner) can kill bite.
• Pad glazing after long descents (like FOD or Spanish mountains) can dramatically reduce power — even if the rotors and pads are clean.
• If the lever pulls firm but there’s no bite, it could be a piston retraction issue, or that the compound isn’t bedding in properly.
• Constant pad swapping can also create rotor surface inconsistency — especially if mixing resin and metallic.
🔁 Saints vs XTR:
• Saint calipers are super powerful but can be sensitive to pad-rotor pairings. If your Saints are in good working order, replacing them may not fix the root cause.
• XTR calipers and levers offer a lighter feel and better modulation, but won’t necessarily fix issues related to contamination or pad performance.
⸻
🔍 What We’d Recommend:
1. Fully clean and reset the system — rotors, calipers, and pistons.
2. Swap in fresh pads (metal or semi-metallic) and ensure they’re properly bedded in. Here’s a quick guide:
👉 Brake Pad Bedding-In Guide
3. Make sure your pistons retract evenly and aren’t sticking.
4. Consider new rotors if there’s uneven wear from previous pad swaps.
⸻
If you’re still struggling after that, XTR calipers and levers could be a good step forward — but we’d always recommend solving the root setup issues first.
And if you’re local, feel free to pop into our workshop — we’re always happy to take a look and help get your brakes running at full power again.
Cheers,
The Gorilla Brakes Team
Hello, I have shiamno saint breaks with a new bike, they worked really well for 3 months and then I flew to Spain on a training week, as soon as got there and built my bike they had less power and squealed. The back brake got better but the front didn’t so we replaced it. They worked until I got back and took my bike to a shop for a check over. They advised a double replace of pads. They did and those didn’t work for long, so I replaced them again to the original saint pads and they worked. Then the shop said I had bent rotors as my levers felt like they hardly moved. We got better xtr discs and then my brakes were spot on. Then after a ride at fod where I still wasn’t happy with the power, they weren’t the same as before. Then I left my bike alone for a week during school and then suddenly they were both contaminated. Then we brought better metal pads with a good cooling system. They worked really well at a national dh and then when I picked up my bike today the front brake had no power and the rotor just slid through a properly closed lever. No squealing and no contamination. I just don’t understand why these brakes won’t work. Is it worth me buying a set of xtr levers and calipers to pair with the rotors ? Are they more reliable or have I just got faulty saints ? Thanks, Charlie.