How to Troubleshoot Ultegra ST‑R8160 TT Brake Set Performance

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The Shimano Ultegra ST‑R8160 TT is a premium time trial and triathlon brake lever and shifter unit, designed to deliver consistent hydraulic disc braking performance with integrated Di2 shifting capabilities. However, even with its high-end engineering, users may encounter occasional issues related to performance, setup, or compatibility. This guide provides a complete breakdown of how to troubleshoot Ultegra ST‑R8160 TT brake set performance, ensuring smooth and reliable braking on every ride.

Tools Required

  • 4 mm and 5 mm hex keys
  • Shimano mineral oil [paid link]
  • Bleed kit for Shimano road disc brakes
  • Torque wrench with 0.5 Nm resolution
  • Clean cloth and isopropyl alcohol
  • Digital calipers (optional)
  • Shimano disc brake spacer/bleed block

Understanding the Ultegra ST‑R8160 TT Brake System

The ST‑R8160 TT is part of Shimano’s 12-speed Di2 ecosystem and is optimized for time trial setups. It combines a slim-profile lever shape with hydraulic disc braking power. It is compatible with Shimano flat-mount calipers and integrates with the Di2 R8100 series. Designed for internal cable routing through TT base bars and aerobars, it uses Shimano’s standard E-Tube wiring system.

Initial Installation and Setup Considerations

Improper installation is one of the primary causes of brake performance issues. Before troubleshooting specific problems, verify the initial setup:

  • Ensure all hydraulic lines are properly cut and installed with Shimano barbs and olives.
  • The brake lever should be torqued to Shimano’s specifications to avoid slippage during braking.
  • Use the provided Shimano bleed block during initial installation to center the pistons and prevent air retention in the calipers.
  • Align the caliper precisely with the rotor using a thin card or Shimano caliper alignment tool to avoid rotor rub.

Poor initial setup can result in spongy lever feel, inconsistent braking force, or rotor misalignment.

Troubleshooting Spongy or Soft Brake Lever Feel

A common issue with hydraulic systems is soft lever feel or increased lever travel before braking force is applied. This usually indicates air in the system or fluid contamination.

Steps to resolve:

  1. Perform a full system bleed using the Shimano one-way bleeding method.
  2. Ensure the bleed port on the lever is the highest point during bleeding to allow all air to escape.
  3. If the issue persists, inspect the caliper pistons. Sticking pistons can mimic the symptoms of air in the system.
  4. Clean and lubricate pistons using Shimano mineral oil before retracting them fully.

Avoid overfilling the reservoir, as this can cause heat expansion-related issues.

Rotor Rub or Noise During Braking

Rotor rub is typically due to improper caliper alignment or piston imbalance.

To address this:

  • Loosen the caliper mounting bolts slightly and apply the brake lever to center the caliper over the rotor. While holding the lever, re-tighten the bolts.
  • Inspect rotor true with a dial indicator or simply spin the wheel and observe side-to-side movement. A warped rotor should be replaced or trued with a rotor truing tool.
  • Check for pad contamination from oil, which can cause noise and reduced friction. Clean the rotor and pads with isopropyl alcohol, or replace pads if contaminated.

Inconsistent Braking Performance Over Long Descents

If braking strength fades during extended braking efforts:

  • Check for brake fluid boiling due to heat buildup. Shimano mineral oil has a high boiling point, but old or contaminated fluid can degrade performance.
  • Inspect brake pads for glazing. Glazed pads develop a shiny surface and reduce braking effectiveness.
  • Use Shimano finned brake pads for improved heat dissipation and ensure rotor size is appropriate (140 mm minimum, 160 mm preferred for heavy braking).

Brake Lever Not Returning Smoothly

A lever that sticks or doesn’t return can result from mechanical or hydraulic causes:

  • Inspect for internal bar routing issues causing excessive bend radius in the hose. Hoses should maintain smooth, wide curves.
  • Ensure the lever pivot is lubricated and free from debris.
  • Verify there is no internal pressure build-up caused by overfilling during a bleed.

Troubleshooting Brake Pad Rubbing After Pad Replacement

New brake pads can introduce clearance issues:

  • Ensure pistons are fully retracted before installing new pads.
  • Insert the bleed block and push pistons back with a plastic tire lever or piston press tool.
  • Perform a short bed-in procedure by braking lightly 20–30 times at moderate speed. This helps establish rotor-pad conformity.

Customization and Optimization Tips

To maximize performance on a TT bike setup:

  • Use Shimano RT-CL800 rotors with Ice Tech Freeza for heat control.
  • Trim hose lengths to minimum necessary to reduce fluid volume and improve modulation.
  • Integrate with R8170 series calipers for perfect lever-to-caliper ratio.
  • Consider using the ST-R9160 if you prefer fully dedicated Di2-only functionality without hydraulic braking.

Compatibility Insights

The Ultegra ST‑R8160 TT:

  • Is compatible with all Shimano 12-speed Di2 road derailleurs (R8100 series).
  • Pairs exclusively with Shimano flat-mount hydraulic calipers.
  • Uses Shimano EW-SD300 E-Tube wires, not the older SD50 standard.
  • Must be paired with a Di2 Junction A or Wireless Unit depending on bar routing.

Ensure that the ST‑R8160 is not mixed with mechanical derailleurs or non-flat-mount disc calipers.

Comparison: Ultegra ST‑R8160 TT vs Dura-Ace ST‑R9180 TT

While similar in design, the Dura-Ace ST‑R9180 TT offers slight enhancements:

  • Weight savings due to carbon fiber construction.
  • Firmer lever feel thanks to stiffer pivot and reduced flex.
  • Enhanced adjustability on lever reach and positioning.

However, the ST‑R8160 offers near-identical performance at a significantly more accessible price point, making it the more practical choice for non-elite racers.

Frequently Asked Questions

1. Can I use the Ultegra ST‑R8160 TT with rim brakes?
No, this model is strictly for hydraulic disc brake systems and is incompatible with rim braking setups.

2. How often should I bleed the ST‑R8160 TT brakes?
Shimano recommends a full bleed annually, or anytime the brakes feel soft or spongy.

3. Why is my lever travel longer than expected?
This usually indicates air in the system or misaligned calipers. Rebleeding and caliper centering typically resolve this.

4. Are ST‑R8160 TT levers adjustable for reach?
Yes, they include a reach adjustment feature via a 2 mm hex screw on the lever body.

5. Do I need to bed-in new brake pads?
Yes, performing a bedding-in process ensures optimal braking performance and pad longevity.

6. What rotors should I use with ST‑R8160 TT for best performance?
Use Shimano’s RT-CL800 or RT-MT800 rotors with Ice Tech for maximum heat management and modulation.