1. Introduction
This manual provides detailed instructions for the installation, adjustment, operation, and maintenance of your Shimano TZ31 7-speed direct mount rear derailleur. This component is designed for use on mountain bikes and road bikes equipped with a 6 or 7-speed drivetrain and a direct mount frame interface. Proper installation and adjustment are crucial for optimal performance and longevity of the derailleur.
2. Safety Information
- Always wear appropriate safety gear, including eye protection, when working on your bicycle.
- If you are unsure about any installation or adjustment procedure, consult a professional bicycle mechanic. Incorrect installation can lead to serious injury or damage to your bicycle.
- Ensure all bolts are tightened to the manufacturer's specified torque values. Overtightening can strip threads, while undertightening can lead to component failure.
- Keep hands and clothing clear of moving parts, especially the chain and gears, when the bicycle is in motion or being adjusted.
- Regularly inspect the derailleur for signs of wear, damage, or loose components. Replace worn or damaged parts immediately.
3. Product Overview
The Shimano TZ31 is a robust rear derailleur designed for reliable shifting across 6 or 7-speed cassettes. It features a direct mount design, which integrates directly into compatible bicycle frames, offering a secure and stable connection.
Key Components:
- Derailleur Body: The main housing that attaches to the bike frame.
- Pulley Cage: Holds the two jockey wheels (guide pulley and tension pulley) that guide the chain.
- High (H) Limit Screw: Adjusts the outer limit of the derailleur's movement, preventing the chain from shifting past the smallest cog.
- Low (L) Limit Screw: Adjusts the inner limit of the derailleur's movement, preventing the chain from shifting past the largest cog.
- B-Tension Screw: Adjusts the distance between the guide pulley and the cassette cogs.
- Cable Anchor Bolt: Secures the shift cable to the derailleur.
4. Setup and Installation
4.1 Tools Required:
- Hex key set (typically 5mm)
- Cable cutters
- Phillips head screwdriver
- Torque wrench (recommended)
4.2 Mounting the Derailleur:
- Ensure your bicycle frame has a direct mount hanger. The TZ31 is designed for this type of mounting.
- Align the derailleur's mounting bolt with the threaded hole on the frame's derailleur hanger.
- Thread the mounting bolt into the hanger by hand to ensure it is not cross-threaded.
- Using a hex key, tighten the mounting bolt. Refer to your bicycle frame manufacturer's specifications for the correct torque value, typically around 8-10 Nm. Do not overtighten.
4.3 Installing the Shift Cable:
- Route the shift cable from your shifter through the frame's cable guides to the rear derailleur.
- Ensure the cable housing is properly seated in all stops.
- With the shifter in the highest gear (smallest cog position), pull the cable taut and insert it into the cable anchor bolt on the derailleur.
- Tighten the cable anchor bolt securely. Do not overtighten.
4.4 Limit Screw Adjustment:
Limit screws prevent the chain from shifting off the cassette into the spokes or frame.
- High (H) Limit Screw: Shift the chain to the smallest cog on the cassette. Turn the H-screw clockwise until the guide pulley is directly aligned with the center of the smallest cog. Turn the screw counter-clockwise slightly if the chain struggles to shift to the smallest cog.
- Low (L) Limit Screw: Shift the chain to the largest cog on the cassette. Turn the L-screw clockwise until the guide pulley is directly aligned with the center of the largest cog. Turn the screw counter-clockwise slightly if the chain struggles to shift to the largest cog.
4.5 B-Tension Adjustment:
The B-tension screw adjusts the gap between the guide pulley and the cassette cogs.
- Shift the chain to the largest cog on the cassette.
- Turn the B-tension screw (located on the derailleur body, usually facing the front of the bike) until the guide pulley is as close as possible to the largest cog without touching it. A gap of 5-6mm is generally ideal.
4.6 Indexing Adjustment:
Indexing ensures smooth and precise shifting between all gears.
- With the chain on the smallest cog, shift one click towards a larger cog. If the chain does not shift smoothly, turn the barrel adjuster (usually located on the shifter or near the derailleur cable stop) counter-clockwise in small increments until it shifts cleanly.
- If the chain overshifts or makes noise, turn the barrel adjuster clockwise in small increments.
- Repeat this process, shifting through all gears, fine-tuning the barrel adjuster until all shifts are smooth and quiet.
5. Operating Instructions
To operate the Shimano TZ31 rear derailleur, use your bicycle's rear shifter. The shifter controls the tension of the derailleur cable, which in turn moves the derailleur cage across the cassette cogs.
- Shifting to a Larger Cog (Easier Gear): Press the shifter lever to release cable tension. The derailleur will move inward, shifting the chain to a larger cog.
- Shifting to a Smaller Cog (Harder Gear): Press the shifter lever to pull the cable, increasing tension. The derailleur will move outward, shifting the chain to a smaller cog.
For optimal performance and to prevent damage, avoid shifting under heavy pedaling load. Anticipate terrain changes and shift proactively.
6. Maintenance
Regular maintenance will extend the life of your derailleur and ensure consistent shifting performance.
6.1 Cleaning:
- After each ride, especially in wet or dirty conditions, clean the derailleur and chain.
- Use a degreaser and a brush to remove grime from the pulley wheels and derailleur body. Rinse thoroughly with water and dry.
6.2 Lubrication:
- Apply a small amount of bicycle-specific chain lubricant to the chain after cleaning and drying.
- Occasionally, apply a light lubricant to the pivot points of the derailleur to ensure smooth movement. Avoid over-lubricating, as this can attract dirt.
6.3 Inspection:
- Regularly check the derailleur hanger for alignment. A bent hanger is a common cause of poor shifting.
- Inspect the pulley wheels for wear. Worn pulleys can cause noisy shifting and poor chain retention.
- Check all bolts for tightness, including the mounting bolt and cable anchor bolt.
- Examine the shift cable and housing for fraying, kinks, or corrosion. Replace if necessary.
7. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Chain skips gears or shifts poorly | Incorrect indexing, bent derailleur hanger, worn chain/cassette, stiff cable. | Adjust barrel adjuster (Section 4.6). Check hanger alignment. Inspect and replace worn drivetrain components. Lubricate or replace cable/housing. |
| Chain falls off smallest cog | H-limit screw set too far out. | Turn H-limit screw clockwise in small increments (Section 4.4). |
| Chain falls off largest cog (into spokes) | L-limit screw set too far out. | Turn L-limit screw clockwise in small increments (Section 4.4). |
| Noisy shifting or chain rubbing | Incorrect B-tension, misaligned derailleur, dirty components. | Adjust B-tension screw (Section 4.5). Check hanger alignment. Clean and lubricate derailleur and chain (Section 6.1, 6.2). |
| Difficulty shifting to larger cogs | Insufficient cable tension, stiff cable/housing. | Turn barrel adjuster counter-clockwise (Section 4.6). Lubricate or replace cable/housing. |
| Difficulty shifting to smaller cogs | Excessive cable tension, stiff cable/housing. | Turn barrel adjuster clockwise (Section 4.6). Lubricate or replace cable/housing. |
8. Specifications
- Model: Shimano TZ31 (TZ 31-21)
- Speed Compatibility: 6/7 Speed
- Mount Type: Direct Mount
- Material: Aluminum (with high-quality plastic and alloy components)
- Weight: Approximately 265g
- Compatible Bike Types: Mountain Bikes (MTB), Road Bikes
9. Warranty and Support
For warranty information or technical support regarding your Shimano TZ31 rear derailleur, please refer to the official Shimano website or contact your local authorized Shimano dealer. Keep your proof of purchase for any warranty claims.
