The Most Common Shimano FC-6700 Chainring Problems and How to Solve Them

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The Shimano FC-6700 [paid link] is a popular chainring model used in many road bike drivetrains, known for its smooth shifting performance and durable construction. However, even with its reputation for quality, issues can arise over time. This article will address the most common problems encountered with the Shimano FC-6700 [paid link] chainring and provide detailed instructions on how to solve them.

1. Poor Shifting Performance

One of the most frequent issues cyclists face with the Shimano FC-6700 [paid link] chainring is poor shifting. When the chain struggles to shift smoothly from one ring to the next, it can lead to a frustrating ride and potentially cause additional wear on your drivetrain components.

Causes:

  • Worn Chainring Teeth: Over time, the teeth of the chainring can wear down, causing poor engagement with the chain.
  • Incorrect Chain Length: If the chain is too long or too short, it can interfere with smooth shifting.
  • Improper Front Derailleur Adjustment: An incorrectly adjusted front derailleur can lead to inaccurate shifting, making it difficult for the chain to move across the chainring properly.

Solutions:

  • Check Chainring Teeth: Inspect the teeth for wear or damage. If the teeth are worn down, it’s time to replace the chainring.
  • Verify Chain Length: Ensure the chain is the correct length by checking if the chain runs smoothly through the drivetrain when shifted to the largest and smallest chainrings. Adjust the chain length if necessary.
  • Adjust Front Derailleur: Ensure the front derailleur is correctly aligned and adjusted according to Shimano’s specifications. Fine-tune the limit screws and the derailleur position to ensure the chain can shift properly across the entire range of the chainrings.

2. Chain Dropping Off the Chainring

Another common issue with the Shimano FC-6700 is the chain dropping off the chainring, especially when shifting between gears. This can happen either from the outer or inner ring, causing a dangerous situation for the rider.

Causes:

  • Incorrect Chainring Bolts Tension: If the chainring bolts are not tightened properly, the chainring may move, causing misalignment.
  • Loose or Damaged Crankset: A loose or worn-out crankset may cause the chainring to become misaligned.
  • Poor Chainline: A poor chainline can cause the chain to shift unpredictably, leading to it dropping off the chainring.

Solutions:

  • Tighten Chainring Bolts: Ensure the chainring bolts are tightened to the manufacturer’s specifications. If the bolts are too loose, the chainring can move out of alignment, causing the chain to drop.
  • Inspect Crankset and Bottom Bracket: Check the crankset and bottom bracket for any loose components. If the crankset is worn or damaged, it may be necessary to replace it.
  • Adjust Front Derailleur: Ensure the front derailleur is positioned correctly relative to the chainring, providing a straight chainline for smoother shifting.

3. Noisy Pedaling

If your Shimano FC-6700 chainring produces a grinding, clicking, or creaking sound while pedaling, this can be an indication of several potential issues.

Causes:

  • Worn Chainring Teeth or Chain: If either the chainring or chain is worn, it may cause noises during pedaling as the chain fails to engage properly with the teeth.
  • Incorrect Chainring Installation: If the chainring is not installed correctly, it may not align properly with the rest of the drivetrain, leading to noise.
  • Lack of Lubrication: Insufficient lubrication on the chain and chainring can result in friction and noise.

Solutions:

  • Inspect the Chainring and Chain: Check for any signs of wear on both the chainring and chain. Replace the worn-out parts if necessary to restore smooth pedaling.
  • Reinstall the Chainring: If the chainring was not installed properly, remove it and reinstall it, making sure it is aligned correctly.
  • Lubricate the Chain and Chainring: Regularly clean and lubricate the chain and chainring to reduce friction and prevent noise. Use a high-quality bike lubricant specifically designed for drivetrains.

4. Chainring Wear

Over time, the Shimano FC-6700 chainring can experience wear, especially after long rides or if the bike is used in harsh conditions. This wear can lead to decreased performance and longevity of the drivetrain.

Causes:

  • Frequent Shifting Under Load: Shifting while under heavy pedaling load can cause increased wear on the chainring teeth.
  • Improper Cleaning: Failing to clean the chainring and chain regularly can lead to dirt and grime buildup, accelerating wear.
  • Poor Chain Condition: A worn-out chain can cause accelerated wear on the chainring, leading to a rough ride and inefficient power transfer.

Solutions:

  • Replace Worn Chainring: If the teeth are visibly worn down or misshapen, it’s time to replace the chainring.
  • Clean Regularly: Clean the chainring and drivetrain regularly to remove dirt, grime, and debris that can accelerate wear. Use a degreaser and a soft brush to clean the chainring after each ride.
  • Replace the Chain: Regularly inspect the condition of your chain and replace it when it becomes worn. A worn chain can damage the chainring, so keeping both components in good condition is essential for long-term performance.

5. Chainring Bolt Loosening

A loose chainring bolt can result in rattling sounds, decreased shifting performance, and can even cause the chainring to become detached in extreme cases.

Causes:

  • Over-tightening or Under-tightening Bolts: Both over-tightening and under-tightening the chainring bolts can lead to issues. Over-tightening can cause damage to the bolt or threading, while under-tightening can cause the chainring to move.
  • Vibration: Over time, vibrations from pedaling can cause chainring bolts to loosen.

Solutions:

  • Correctly Tighten Bolts: Use a torque wrench [paid link] to tighten the chainring bolts to Shimano’s recommended torque specification. Typically, Shimano recommends tightening chainring bolts to a torque value of around 12–14 Nm.
  • Use Threadlocker: If the bolts continue to loosen, you can apply a small amount of threadlocker to help keep the bolts in place. However, be cautious when using threadlocker as it may make future maintenance more difficult.

Conclusion

The Shimano FC-6700 chainring is a durable and reliable component, but like any part of your drivetrain, it requires regular maintenance and attention. By addressing common issues such as poor shifting, chain dropping, noisy pedaling, chainring wear, and loose bolts, you can ensure that your FC-6700 chainring continues to perform at its best. Regular inspection and timely replacement of worn parts will help you enjoy smoother rides and a more efficient drivetrain for years to come.