The Shimano Ultegra FD-6700 [paid link] front derailleur is a precise component designed to deliver crisp shifting performance. However, even the most advanced derailleur will perform poorly if its limit screws are not adjusted correctly. Proper limit screw adjustment prevents chain rub, eliminates overshifting, and ensures smooth transitions between chainrings. This guide explains how to fine-tune the FD-6700 [paid link]’s limit screws for optimal performance.
Understanding Limit Screws on the FD-6700 [paid link]
The FD-6700 features two limit screws, marked with an “L” and “H.” These screws control the derailleur’s lateral movement range. The low limit screw (L) sets the inner cage boundary to prevent the chain from dropping into the bottom bracket when shifting to the small chainring. The high limit screw (H) defines the outward boundary, preventing the chain from overshooting the big ring. If either screw is misadjusted, shifting accuracy will suffer and drivetrain wear may increase.
Tools Required
- 2mm or 2.5mm hex key [paid link] (for limit screws)
- 5mm hex key [paid link] (for cable pinch bolt if needed)
- Bike stand [paid link] (recommended for stable adjustment)
Setting the Low Limit Screw
Begin by shifting the chain to the small chainring at the front and the largest cog at the rear. In this position, the derailleur cage should align closely with the chain but must not press against it. Turn the L screw clockwise to move the cage outward or counterclockwise to allow it to move inward. The correct setting leaves approximately 0.5–1mm clearance between the inner cage plate and the chain. This ensures smooth running without chain rub or risk of derailment.
Adjusting the High Limit Screw
Next, move the chain to the big chainring at the front and the smallest cog at the rear. Here, the derailleur’s outer cage plate should sit close to the chain, again with a 0.5–1mm gap. Adjust the H screw clockwise to restrict outward movement or counterclockwise to permit more travel. If the screw is too tight, the derailleur won’t shift onto the big ring. If it’s too loose, the chain may overshoot and fall off. Proper alignment guarantees quick, secure shifts.
Fine-Tuning for Smooth Shifting
Once both limits are set, test the shifting across the full range of chainrings and cogs. Pay special attention to diagonal gear combinations, such as the small chainring paired with smaller cogs, where chain rub is more likely. The FD-6700 includes a trim function via the STI levers, which can be used to eliminate minor rub. However, correct limit screw adjustment should reduce reliance on trimming. If rubbing persists despite correct limits, check cable tension, derailleur height, and alignment.
Common Mistakes to Avoid
Many riders mistakenly over-tighten the limit screws, restricting derailleur movement so much that shifts become sluggish. Conversely, leaving the screws too loose allows overshifting, which can damage the chain or chainrings. Another common error is adjusting the screws before ensuring the derailleur’s cage height and alignment are correct. The FD-6700 requires the cage to be parallel to the chainrings and positioned just 1–3mm above the tallest teeth for best results.
Troubleshooting Persistent Issues
If, after careful adjustment, the derailleur still hesitates or rubs, the problem may not be with the limit screws. Common culprits include insufficient cable tension, worn chainrings, or a bent derailleur hanger. In such cases, re-check installation parameters before re-adjusting limits. A correctly installed FD-6700 with properly set limit screws should deliver sharp, reliable shifts across the full drivetrain.
Conclusion
Proper limit screw adjustment is essential to unlocking the full performance of the Shimano Ultegra FD-6700 front derailleur. By carefully setting both the low and high screws, riders can ensure precise shifting, protect their drivetrain, and avoid frustrating chain drops or overshifts. Taking the time to dial in these adjustments will keep the FD-6700 operating at its intended high standard for many miles.