Adjusting Your Clarks CMD22 Disc Brake Pads

Fine-Tuning Your Clarks CMD22 Mechanical Disc Brakes

When it comes to bicycle braking systems, particularly mechanical disc brakes, precision adjustment is key to ensuring optimal performance, safety, and longevity of your components. The Clarks CMD22 Dual Piston Mechanical Disc Brake System, while lauded for its power and ease of use compared to single-piston systems, can sometimes require a bit of fine-tuning. This guide will walk you through the process of adjusting your brake pads for the Clarks CMD22, ensuring a smooth and responsive braking experience.

The Clarks CMD22 system is designed for road, cyclo-cross, and gravel cycling, offering a significant upgrade from older single-piston cable systems. Its dual-piston design means that both pads move towards the rotor simultaneously. This leads to more even pad wear, improved stopping power, and, crucially, a more straightforward setup and adjustment process compared to its single-piston counterparts. Let's delve into how you can ensure your brakes are performing at their peak.

Understanding the Dual-Piston Advantage

Before we get into the adjustment process, it's worth appreciating the engineering behind the dual-piston mechanism. Unlike single-piston systems where one pad is stationary and the other moves, both pads in the CMD22 are actuated. This has several benefits:

• Even Pad Wear: Both pads contact the rotor with equal force, meaning they wear down at a similar rate. This extends the life of your pads and ensures consistent braking performance over time.
• Improved Power: With two contact points, the brake can exert more even pressure on the rotor, translating to stronger and more controlled stopping power.
• Easier Adjustment: While mechanical systems inherently require more manual adjustment than hydraulics, the dual-piston design simplifies the process of centering the caliper and ensuring proper pad contact.

What You'll Need: Essential Tools

To adjust your Clarks CMD22 brake pads effectively, you'll need a few basic tools. Having these readily available will make the process smoother:

• 5mm Allen Key: For mounting the callipers and tightening bolts.
• 3mm Allen Key: For fine-tuning pad adjustment.
• Torx 25 Driver: For mounting disc rotors to the hub.
• Disposable Examination Gloves: To keep grease and dirt off your components and hands.
• Torque Wrench (Optional but Recommended): To ensure bolts are tightened to the correct specifications (e.g., 6-8 Nm for rotors, 6 Nm for calliper mounting bolts).
• Cable Cutter/Stripper: If you need to adjust cable length or re-terminate cables.

Step-by-Step Adjustment Guide

The setup and adjustment of the Clarks CMD22 are generally straightforward, similar to other popular dual-piston mechanical disc brakes like the TRP Spyre. Follow these steps carefully:

1. Initial Rotor Mounting

If you are installing new rotors or reattaching existing ones, ensure they are mounted correctly to your hubs. Use your Torx 25 driver to secure the 6-bolt rotors. It's crucial not to overtighten them; aim for approximately 6-8 Nm of torque. Make sure the rotor spins freely and doesn't wobble.

2. Caliper Mounting

Clean the threads on your frame and fork where the callipers will be mounted. Offer the calliper and the appropriate mount (ISO or Post Mount, depending on your frame/fork) to the mounting points. Use your 5mm Allen key to bolt the callipers on, but leave them slightly loose for now. This initial looseness allows for easier alignment in the next steps.

3. Cable Attachment

Cut your brake cables to the appropriate length, ensuring they have a clean, smooth path to the calliper without any sharp bends or kinks. Feed the inner cable into the calliper's actuation mechanism. Ensure the cable end sits securely. Tighten the cable pinch bolt using your 5mm Allen key to approximately 6 Nm. Remember, decent cable sets, particularly those with compressionless housings, make a significant difference in brake feel and power.

4. Wheel Installation and Centring

Reinstall your wheels onto the bike. With the wheels in place, pull the brake lever firmly into the handlebar. This action will naturally pull the pistons and pads towards the rotor, helping to centre the calliper. While holding the brake lever firmly, use your 5mm Allen key to tighten the calliper mounting bolts to their final torque (around 6 Nm). This is a critical step for achieving proper pad alignment.

5. Initial Brake Lever Feel and Adjustment

Spin each wheel to check for any rubbing. If there is slight rubbing, it might be due to minor cable stretch or imperfect calliper centring. Pump the brake lever several times (around ten) to allow the system to settle and take up any initial cable slack. Use the barrel adjuster located on the brake lever or calliper (if present) to fine-tune the tension and eliminate any unwanted rubbing. You want the pads to be close to the rotor without touching it when the lever is not engaged.

6. Fine-Tuning Pad Position (3mm Allen Key)

The Clarks CMD22, like many dual-piston mechanicals, allows for individual pad adjustment. This is where the 3mm Allen key comes into play.

• Identifying the Adjustment Screws: Look for small grub screws, typically located on the back of the calliper body, one for each piston.
• Adjusting the Inner Pad: If the rotor is too close to the inner pad (the one closest to the wheel spokes), you'll need to back off the inner pad. Insert the 3mm Allen key into the adjustment screw for the inner piston and turn it counter-clockwise.
• Adjusting the Outer Pad: If the rotor is too close to the outer pad (the one furthest from the wheel spokes), you'll need to back off the outer pad. Insert the 3mm Allen key into the adjustment screw for the outer piston and turn it counter-clockwise.
• Bringing Pads Closer: If you need to bring the pads closer to the rotor (e.g., if the lever has too much travel), turn the adjustment screws clockwise.

The goal is to have the rotor running freely between the pads with minimal clearance. Make small, incremental adjustments and re-check wheel spin and lever feel after each adjustment. Remember that the cable tension also plays a role, so you might need to use both the barrel adjuster and the pad adjustment screws in conjunction.

Troubleshooting Common Issues

Even with the best intentions, you might encounter a few common issues:

Issue: Brake Pads Rubbing on the Rotor

Cause: Caliper not perfectly centred, or pads are too close.

Solution:

• Loosen the calliper mounting bolts.
• Gently pull the brake lever to centre the calliper.
• Tighten the mounting bolts while holding the lever.
• If rubbing persists, use the 3mm Allen key to slightly back off the relevant pad(s) (turn counter-clockwise).

Issue: Brake Lever feels Spongy or Has Too Much Travel

Cause: Cable tension is too loose, or there's excess slack.

Solution:

• Use the barrel adjuster to increase cable tension (turn counter-clockwise).
• If the barrel adjuster is out of range, you may need to re-terminate the cable, pulling it tighter before pinching it down.
• Ensure your cable and housing are in good condition; worn or contaminated cables can reduce performance.

Issue: Uneven Pad Wear

Cause: Caliper not properly centred, or a single-piston system (though CMD22 is dual-piston).

Solution: Ensure both pistons are moving freely and that the calliper is correctly aligned. The dual-piston design should inherently promote even wear if set up correctly.

Pad Compatibility and Replacement

A significant advantage of the Clarks CMD22 is its compatibility with Shimano pad patterns. This means that finding replacement brake pads should be relatively straightforward, even when you're out on a tour or far from a specialist bike shop. Always ensure you purchase pads specifically designed for mechanical disc brakes and compatible with Shimano patterns.

When to Seek Professional Help

While adjusting mechanical disc brakes is a manageable task for most home mechanics, there are times when professional assistance is advisable:

• If you've followed all the steps and are still experiencing significant rubbing or poor braking performance.
• If you suspect damage to the calliper, rotor, or mounting points.
• If you're uncomfortable performing any of these adjustments yourself.

Conclusion

Adjusting your Clarks CMD22 Dual Piston Mechanical Disc Brake pads is a rewarding process that can significantly enhance your riding experience. By understanding the dual-piston advantage and following these step-by-step instructions, you can achieve precise, powerful, and reliable braking. Remember to perform regular checks and adjustments to maintain optimal performance and safety on all your rides, whether on the road, tackling cyclo-cross courses, or exploring gravel paths.

Frequently Asked Questions (FAQ)

Q1: How often should I check and adjust my brake pads?
It's good practice to check your brake pad alignment and lever feel before every ride, especially after encountering rough terrain or if you notice any changes. A more thorough adjustment might be needed every few hundred miles or when you notice increased lever travel or rubbing.

Q2: Can I use hydraulic brake pads with my CMD22 mechanical brakes?
No, you should only use brake pads specifically designed for mechanical disc brake systems and compatible with the Shimano pad pattern accepted by the CMD22. Hydraulic pads are designed for a different operating system.

Q3: My brake lever feels stiff. What could be the cause?
A stiff lever can be caused by a few things: contaminated or damaged brake cables/housing, a dirty or seized actuation mechanism within the calliper, or the brake pads themselves being worn out or contaminated.

Q4: Do I need to bleed my brakes after adjusting the pads?
No, the Clarks CMD22 are mechanical brakes, meaning they use cables, not hydraulic fluid. Therefore, bleeding is not required for adjustment.

Q5: What is the difference between adjusting cable tension and pad position?
Adjusting cable tension (using the barrel adjuster) primarily affects the lever's reach and engagement point. Adjusting pad position (using the 3mm Allen key) fine-tunes the distance of the pads from the rotor, crucial for eliminating rubbing and ensuring optimal contact when the brake is applied.

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