The Shimano ST-4725 dual control lever is part of the TIAGRA hydraulic disc brake system, designed specifically for riders with smaller hands. Featuring a compact lever shape, smooth braking response, and precise shifting, this model offers improved ergonomics and comfort for road cyclists. 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-4725 dual control lever.
Tools Required
To install and maintain the Shimano ST-4725 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 [paid link]
- 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-4725 Dual Control Lever
Mounting the Lever on the Handlebar
Before installing the ST-4725 lever, ensure the handlebar is clean and free of grease or debris. Proper positioning of the levers is essential 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, positioning it to align with the rider’s hand placement. The recommended position is where the top of the lever hood aligns with the flat section of the handlebar. Once properly positioned, tighten the clamp bolt to 6–8 N·m using a torque wrench [paid link] to prevent slippage.
Installing the Shifting Cable
The shifting cable must be correctly installed to ensure smooth and precise gear changes. Begin by shifting to the highest gear to expose the cable entry port. Insert the inner shifting cable through the entry hole and route it along the outer casing toward the derailleur. Shimano recommends using SP41 outer casing for optimal shifting performance.
Once inserted, secure the outer casing in the designated cable stops along the frame, ensuring there are no sharp bends or kinks in the cable housing. Poor routing can cause increased friction, slow shifting, or derailleur misalignment.
For further guidance on shifting performance, refer to Troubleshooting Common Gear Shifting Problems on Your Road Bike.
Connecting the Hydraulic Brake Hose
If the brake hose is pre-installed, 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. A clean, perpendicular cut prevents leaks.
- Insert the olive and connector insert into the brake hose end.
- 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 [paid link].
At this point, the brake system must be bled to eliminate trapped air.
Adjusting the Shimano ST-4725 Dual Control Lever
Reach Adjustment
The ST-4725 lever is specifically designed for riders with smaller hands, but fine-tuning the lever reach further enhances comfort and control. Using a 2.5 mm hex wrench, adjust the reach by turning the reach adjustment screw:
- Clockwise moves the lever closer to the handlebar.
- Counterclockwise increases the reach, creating more space between the lever and the bar.
After adjustment, test the reach by engaging the lever. It should provide comfortable finger placement without excessive stretch.
Bleeding the Brake System
To maintain consistent braking performance, Shimano recommends bleeding the hydraulic system after installation or when the brake feel becomes spongy.
- Remove the bracket cover and position the bleed port screw facing upward.
- Use a 2.5 mm hex wrench to remove the bleed screw, then install the Shimano oil funnel.
- Fill the funnel with Shimano mineral oil [paid link] and gently pump the brake lever to release trapped air bubbles.
- Once air bubbles stop appearing, plug the funnel, reinstall the bleed screw, and clean any excess oil using isopropyl alcohol.
For additional bike maintenance techniques, refer to Why You Need a Bike Tune-Up and How Often You Should Get One.
Maintaining the Shimano ST-4725 Dual Control Lever
Routine maintenance ensures long-term reliability and smooth braking/shifting performance. Shimano recommends inspecting the brake and shifting systems every 5,000 km, or more frequently in wet or high-stress riding conditions.
Replacing the Brake Fluid
Over time, Shimano mineral oil [paid link] absorbs moisture, reducing braking efficiency. It is recommended to replace the brake fluid annually or whenever the oil appears discolored. Follow the bleeding process outlined earlier to refresh the system.
Cleaning and Lubrication
Regular cleaning prevents dirt buildup and shifting resistance. Use isopropyl alcohol and a clean rag to wipe down the lever body and hood. Avoid degreasers or harsh solvents, as they may damage the rubber hood and internal components.
Inspect the shifting cable for signs of fraying or excessive wear. If shifting feels sluggish, apply Shimano SP41 grease inside the cable housing for smoother movement.
If brake performance declines, check the brake pads for wear. Worn pads should be replaced promptly to maintain optimal stopping power.