Shimano’s Ultegra ST‑R8160 TT shifters and brake system are purpose-built for time trial and triathlon performance. As part of the R8100 series, these dual control levers are paired with hydraulic disc calipers, designed for precise modulation and consistent stopping power under race conditions. This guide provides detailed, step-by-step instructions on adjusting Ultegra ST‑R8160 TT brake calipers for optimal performance, covering installation, maintenance, and common troubleshooting techniques.

Tools Required

• 5 mm Allen wrench
• Torque wrench (with Nm scale)
• Shimano mineral oil [paid link]
• Bleed kit (compatible with Shimano hydraulic brakes)
• Flat-blade screwdriver
• Clean rags
• Isopropyl alcohol
• Caliper alignment tool (optional but recommended)
• Rotor truing tool (if rotor issues are present)

Brake Caliper Installation

Proper installation of the hydraulic brake calipers is essential for achieving full braking efficiency and minimizing post-installation adjustments.

Mounting the Calipers
The Ultegra ST‑R8160 TT system uses Shimano flat-mount calipers. Ensure the mounting bolts and adapters match the fork or frame’s specifications.

The caliper should sit flush against the mount with no gaps. Use the 5 mm Allen wrench to snug the bolts lightly. Do not torque them fully until alignment is complete.

Torque Specifications
Shimano specifies 6–8 Nm for flat-mount caliper bolts. Once alignment is correct, tighten the bolts using a torque wrench to the lower end of this range and re-check caliper centering before final torqueing.

Initial Caliper Adjustment

Rotor Clearance
The caliper pistons should evenly straddle the brake rotor without rubbing. Begin by spinning the wheel and observing for rotor contact. Light scraping indicates misalignment or piston imbalance.

Centering the Caliper
Loosen the caliper bolts just enough to allow the caliper to float. While applying the brake lever to center the caliper over the rotor, tighten the bolts incrementally. Release the lever and spin the wheel to confirm clearance. Repeat if rubbing persists.

Piston Reset
If the pistons are uneven, remove the wheel and gently push both pistons back into the caliper body using a flat plastic tire lever or piston reset tool. Reinstall the wheel and recheck rotor clearance.

Fine-Tuning Brake Lever Feel

Lever Stroke and Engagement Point
The ST‑R8160 TT levers allow for reach adjustment to fine-tune lever position for different hand sizes. Using a 2 mm Allen key, turn the reach adjustment screw on the inside of the lever body.

To adjust the engagement point, perform a fluid bleed if the lever feels spongy or lacks bite. A firm, immediate response indicates proper setup.

Bleeding the Hydraulic System

Over time, air can enter the hydraulic system or fluid may degrade, affecting performance.

When to Bleed

• Squishy or inconsistent lever feel
• Brake fade under repeated use
• After transporting the bike or replacing hoses

Bleeding Procedure
Attach the Shimano bleed funnel to the lever body with the lever in horizontal position. Remove the bleed screw and fill the funnel with Shimano mineral oil. At the caliper, connect the hose to the bleed port and open the port bolt.

Gently pump the brake lever to push air bubbles out. Once clear, close the bleed port, remove the funnel, and reinstall the screws. Clean excess fluid with isopropyl alcohol.

Common Troubleshooting Issues

Persistent Rotor Rub
This often results from improper alignment or a bent rotor. Use a rotor truing tool to correct minor warps. Ensure the caliper is centered and pistons retract evenly.

Brake Fade or Weak Braking
This usually stems from contaminated pads or glazed rotors. Clean the rotors and replace pads if needed. Always use Shimano-compatible pads.

Lever Pulls to Bar Without Resistance
Indicates severe air ingress or fluid loss. Inspect for leaks at the caliper and hose connections. Bleed the system thoroughly.

Maintenance Best Practices

Pad Inspection
Check pad thickness regularly. Replace pads when the compound reaches 1 mm or less. Use only Shimano-approved pads for consistent modulation.

Rotor Cleaning
Use isopropyl alcohol on a clean rag to wipe rotors. Avoid degreasers or non-approved cleaners, which can contaminate the pads.

Annual Bleed
Even with minimal use, bleed the brake system annually to maintain responsiveness and ensure fluid purity.

Performance Optimization

Pad Compound Choice
Choose resin pads for quieter operation and better modulation in dry conditions. Metallic pads offer superior longevity and heat resistance for demanding descents.

Rotor Size Matching
Pairing the caliper with 140 mm or 160 mm rotors depends on rider weight and terrain. Larger rotors increase braking force but add weight.

Hose Length Customization
Trim brake hoses to eliminate slack for a cleaner cockpit and improved pressure response. Re-bleed the system after any hose modification.

Compatibility Considerations

The Ultegra ST‑R8160 TT calipers are fully compatible with Shimano’s 12-speed Di2 drivetrain and hydraulic brake components within the R8100 ecosystem. Ensure rotors and pads also adhere to Shimano’s specifications for thermal and mechanical performance.

Avoid mixing brands in the braking system to prevent compatibility issues, particularly with hose fittings, brake fluid type, and bleed procedure.

Model Comparison

Ultegra ST‑R8160 TT vs. Dura-Ace ST‑R9180 TT
While both are high-performance time trial units, Dura-Ace offers marginal weight savings and refined ergonomics. However, Ultegra delivers nearly identical hydraulic performance at a more accessible price point, making it ideal for serious amateur racers.

Ultegra ST‑R8160 TT vs. ST-R8060
The R8160 introduces updated ergonomics, improved integration with 12-speed drivetrains, and better hose routing than the prior R8060 model. Compatibility is enhanced, but users must upgrade to 12-speed Di2 to fully benefit.

FAQs

1. Can I use Ultegra ST‑R8160 TT calipers with non-Shimano rotors?
Shimano recommends using their Ice-Tech rotors for best thermal performance. While other brands may work, compatibility and braking quality could suffer.

2. How often should I bleed the brake system?
Bleed the system once per year under normal use, or immediately after any sign of air in the line or performance loss.

3. What is the correct rotor size for Ultegra ST‑R8160 TT?
Both 140 mm and 160 mm rotors are compatible. Choose based on weight, braking demands, and frame clearance.

4. Are the ST‑R8160 TT levers adjustable for smaller hands?
Yes, the levers have built-in reach adjustment using a 2 mm hex key to customize lever distance.

5. Can I reuse brake pads after contamination?
No. Once pads are contaminated with oil or degreaser, they lose effectiveness and must be replaced.

6. Do I need special tools for bleeding the Ultegra system?
Yes, a Shimano-compatible bleed kit with a funnel and mineral oil is required for safe and effective bleeding.

Conclusion

Properly adjusting your Shimano Ultegra ST‑R8160 TT brake calipers ensures not just stopping power but race-day confidence. With accurate alignment, regular maintenance, and correct bleeding procedures, this system delivers consistent performance for time trialists and triathletes. By following this guide, you’ll be able to fine-tune your braking setup for reliable, smooth control on every ride.