The Shimano Ultegra ST‑R8160 TT brake lever is a high-performance component designed for time trial and triathlon bikes, integrating precise hydraulic braking with electronic Di2 shifting. Despite its superior engineering, riders may encounter setup or performance issues that require attention. This guide provides a detailed look into diagnosing and fixing common brake problems specific to the Ultegra ST‑R8160 TT brake sets.
Tools Required
- 4mm and 5mm hex wrenches
- Shimano hydraulic disc bleed kit
- Isopropyl alcohol
- Clean microfiber cloths
- Shimano mineral oil [paid link]
- Torque wrench (2–6 Nm range)
- Rotor truing fork (optional)
- Brake pad spacer tool
Understanding the Brake System Design
The Ultegra ST‑R8160 TT uses Shimano’s hydraulic disc brake system paired with dual-control levers. These levers are unique due to their horizontal TT mount orientation and integration with Di2 electronic shifters. The hydraulic system is closed, with mineral oil fluid and flat-mount calipers, ensuring consistent stopping power. Brake performance depends on correct installation, alignment, fluid pressure, and rotor condition.
Diagnosing Spongy or Soft Brake Lever Feel
A common concern with ST‑R8160 TT brakes is a spongy feel at the lever. This typically indicates air in the hydraulic line or fluid degradation.
Begin by checking fluid levels and inspecting for external leaks around the lever body or caliper. If the lever compresses without adequate stopping force, air has likely entered the system. Bleeding the brakes using Shimano’s one-way bleed system restores firmness. Ensure the caliper is oriented correctly during the bleed to prevent air bubbles from remaining trapped.
Also inspect the brake pads and rotors for contamination. Residue from skin oils, degreasers, or road grime can reduce friction and create a squishy feel. Clean the rotor and pad surfaces with isopropyl alcohol and replace contaminated pads as needed.
Resolving Brake Pad Rubbing or Drag
Brake pad drag on the ST‑R8160 TT can result from caliper misalignment, rotor warping, or piston imbalance.
Check that the caliper is centered over the rotor. Loosen the mounting bolts slightly, squeeze the brake lever to center the caliper, and re-tighten to the manufacturer’s torque specification (usually 6 Nm). If pad contact continues, examine the rotor’s trueness. Slight warps can be corrected with a rotor truing tool.
Inspect piston movement by removing the wheel and pads. Press the lever gently and watch for symmetrical piston movement. If one side sticks, apply mineral oil with a Q-tip to lubricate the piston edges and cycle them gently. Avoid overextending the pistons during this process.
Improving Brake Lever Return and Modulation
If the brake lever is slow to return after compression or feels inconsistent, cable tension is not the issue—as this is a hydraulic system—but rather internal fluid friction or contamination.
Bleeding the system thoroughly removes trapped air or old fluid, both of which can interfere with return spring function. Check that the lever pivot is clean and lightly lubricated. Dirty or sticky pivots can delay return and reduce brake modulation precision.
Fixing Inconsistent Braking Force
Inconsistent stopping power from one ride to the next is often caused by pad glazing or uneven rotor wear.
Pad glazing occurs from prolonged light braking and results in shiny, hardened pad surfaces. Lightly sand the pads with 120-grit [paid link] sandpaper and clean thoroughly with alcohol. If the rotor has visible grooves or uneven discoloration, replace it. Shimano recommends using only their specified rotors for optimal compatibility.
Addressing Lever Rattle and Vibration
Rattling at the brake lever body of the ST‑R8160 TT is rare but can occur if the lever body or mount is improperly torqued. Inspect the mounting bolts attaching the TT extension bars and the lever body itself. Torque all bolts to Shimano specifications, and ensure there is no play between the lever and handlebar.
For vibration during braking, especially under high-speed deceleration, confirm that the front axle is secure and that the fork isn’t flexing excessively. Vibration is often due to resonation between the caliper and rotor, so ensure both components are mounted tightly and rotors are clean.
Customizing Brake Lever Reach
The ST‑R8160 TT offers adjustable reach to accommodate various hand sizes and cockpit setups. Under the brake hood, a reach adjustment bolt allows riders to fine-tune lever distance from the bars.
Use a 2mm hex wrench to turn the adjuster clockwise to bring the lever closer or counterclockwise to extend it. Make these adjustments with the rider in the saddle position to simulate real-world grip and reach angles, ensuring the best ergonomic feel.
Optimizing Brake Performance for Racing
For time trialists aiming for optimal braking modulation and response, performance tuning is essential. Use only Shimano RT-MT800 rotors and original brake pads for consistent thermal behavior. Maintain pads at 50% wear or greater to ensure heat dissipation remains effective under sustained braking.
Bleed the system every 12 months or sooner if braking feel degrades. In hot-weather regions or during high-altitude climbs, increased brake fade can occur. Pre-race, clean all braking surfaces and check torque on all bolts to avoid power loss.
Troubleshooting Brake Fade During Long Descents
Shimano’s mineral oil-based system is resistant to fade, but prolonged descents may still generate high rotor temperatures. If fade occurs, first check for pad glazing and rotor discoloration.
Consider switching to Shimano’s finned Ice-Tech pads to enhance heat management. Also verify that you are using the correct rotor size for your frame and fork clearance—larger rotors dissipate heat more effectively.
Comparing the ST‑R8160 TT to Dura-Ace ST‑R9180 TT
While both brake levers share hydraulic functionality and Di2 integration, the Dura-Ace model offers marginal weight savings and slightly higher material stiffness.
Functionally, the braking performance is nearly identical. However, elite racers may prefer the ST‑R9180 for its quicker lever return and titanium hardware. For most riders, the ST‑R8160 TT offers 95% of the performance at a more affordable price point.
Ensuring Compatibility with Drivetrain and Frame
The ST‑R8160 TT is fully compatible with Shimano’s 12-speed Di2 road drivetrains, including Ultegra and Dura-Ace R8100/R9200 series. It pairs best with the BR-R8170 flat-mount calipers and RT-MT800 rotors.
Frame compatibility depends on having internal hose routing for TT extensions and a frame designed for flat-mount disc brakes. When installing, confirm hose length and route to avoid sharp bends that can reduce braking efficiency.
Frequently Asked Questions
1. Why is my Ultegra ST‑R8160 TT brake lever going all the way to the bar?
This usually means there’s air in the system or the fluid level is low. A full bleed using Shimano’s mineral oil will resolve the issue.
2. Can I use non-Shimano pads with the ST‑R8160 TT brake system?
It is strongly recommended to use only Shimano-compatible pads. Third-party pads may affect braking power, noise levels, and rotor wear.
3. How often should I bleed the brakes?
At least once a year or whenever the lever feel becomes soft or inconsistent. Bleed more frequently in hot or mountainous conditions.
4. Is there a way to adjust the free stroke on this lever?
No, the ST‑R8160 TT does not include a free stroke adjustment. Only reach can be modified via the internal screw.
5. Can I convert this lever for mechanical shifting?
No. The ST‑R8160 TT is specifically designed for Shimano Di2 systems and does not support mechanical cable actuation.
6. My brakes are noisy—what’s the cause?
Squealing or grinding often comes from contamination, misalignment, or pad glazing. Clean all parts thoroughly and check for proper pad-to-rotor contact.
Conclusion
Maintaining and optimizing the Shimano Ultegra ST‑R8160 TT brake set is essential for consistent, high-performance braking in time trials and triathlons. By following proper installation, adjustment, and maintenance protocols, riders can eliminate common issues like pad rub, inconsistent lever feel, or fading power. Ensuring compatibility with the rest of the drivetrain and understanding the unique aspects of this TT-specific lever set will help you get the most from your equipment.