The Shimano ST-4720 dual control lever is a part of the TIAGRA series hydraulic disc brake system, designed to provide smooth braking and precise shifting for road bikes. Proper installation, adjustment, and maintenance of this lever ensure consistent braking performance, comfortable reach, and long-term reliability. This guide will walk through the step-by-step process of installing, adjusting, and maintaining the Shimano ST-4720 dual control lever.
Tools Required
To install and maintain the Shimano ST-4720 dual control lever, you will need:
- 2 mm hexagon wrench
- 2.5 mm hexagon wrench
- 4 mm hexagon wrench
- 5 mm hexagon wrench
- Torque wrench[paid link]
- Shimano TL-BT03 / TL-BT03-S bleed kit
- Shimano SM-DISC oil funnel and stopper
- Shimano mineral oil[paid link]
- Isopropyl alcohol and clean rags
- Utility knife
- Shimano TL-BH61 hose tool
- Shimano TL-CT12 cable cutter
Installing the Shimano ST-4720 Dual Control Lever
Mounting the Lever on the Handlebar
Before installing the ST-4720 lever, ensure that the handlebar surface is clean and free from any grease or debris. Proper positioning of the levers is important for ergonomic comfort and optimal braking performance.
Begin by loosening the clamp bolt on the lever using a 5 mm hexagon wrench. Slide the lever onto the handlebar and position it according to your preferred reach and hand placement. The recommended positioning aligns the top of the lever hood with the flat top section of the handlebar. Once satisfied, tighten the clamp bolt to 6–8 N·m using a torque wrench[paid link] to prevent slippage during rides.
Installing the Shifting Cable
Before routing the shifting cable, ensure that the inner cable and outer casing are free from damage or contamination. Shimano recommends using SP41 outer casing for smooth shifting.
Shift the lever to the highest gear to open the cable entry port. Carefully insert the inner shifting cable through the entry hole and guide it along the outer casing toward the derailleur. Once fully inserted, secure the outer casing using the appropriate cable stops. Ensure that there are no sharp bends or kinks in the cable housing, which could cause resistance or sluggish shifting.
For additional tips on shifting performance, refer to Troubleshooting Common Gear Shifting Problems on Your Road Bike.
Connecting the Hydraulic Brake Hose
If the brake hose is already attached, proceed to the bleeding process. If not, follow these steps:
- Cut the brake hose to the correct length using a utility knife or Shimano TL-BH61 hose tool. Ensure a clean, perpendicular cut to prevent fluid leaks.
- Insert the olive and connector insert into the cut end of the brake hose.
- Apply a small amount of Shimano mineral oil[paid link] to the olive before tightening the flare nut.
- Secure the hose into the lever port and tighten the flare nut to 5–6 N·m using a torque wrench.
At this stage, you must bleed the brake system to remove any trapped air.
Adjusting the Shimano ST-4720 Dual Control Lever
Reach Adjustment
The ST-4720 lever allows riders to fine-tune the lever reach for better comfort and control. If you have smaller hands or prefer a closer lever position, you can adjust the reach by turning the reach adjustment screw using a 2.5 mm hex wrench.
- Turning the screw clockwise moves the lever closer to the handlebar.
- Turning the screw counterclockwise increases the reach, allowing more space between the lever and the bar.
After adjusting, test the reach to ensure it provides comfortable finger placement without excessive strain.
Bleeding the Brake System
Bleeding the hydraulic system removes any trapped air bubbles, ensuring consistent brake feel and optimal stopping power. Shimano recommends bleeding the brakes if you experience a spongy brake feel or after installing a new hose.
- Remove the bracket cover and position the bleed port screw facing upward.
- Use a 2.5 mm hex wrench to remove the bleed screw and install the Shimano oil funnel.
- Fill the funnel with Shimano mineral oil[paid link] and gently pump the brake lever to release any trapped air bubbles.
- Once the bubbles stop appearing, plug the funnel, reinstall the bleed screw, and wipe off any excess oil with isopropyl alcohol.
For more detailed maintenance guidance, refer to Why You Need a Bike Tune-Up and How Often You Should Get One.
Maintaining the Shimano ST-4720 Dual Control Lever
Regular maintenance of the ST-4720 dual control lever ensures long-term reliability and prevents shifting or braking issues. Shimano recommends checking the brake and shifting systems every 5,000 km, or more frequently in wet or extreme riding conditions.
Replacing the Brake Fluid
Over time, Shimano mineral oil can degrade, affecting braking performance. It is important to replace the brake fluid annually or if it appears discolored. Follow the bleeding process outlined earlier to refresh the system with new mineral oil.
Cleaning and Lubrication
To keep the lever in peak condition, regularly wipe down the exterior with isopropyl alcohol to remove sweat, dirt, and grime. Avoid using harsh degreasers or solvents, as they can damage the rubber hood and internal components.
Inspect the shifting cable for signs of fraying or excessive wear. If shifting becomes sluggish, apply Shimano SP41 grease to the cable housing to maintain smooth movement.