The Shimano CN-6701 [paid link] chain is a premium 10-speed chain designed specifically for road cyclists seeking efficient power transfer and quiet drivetrain performance. Despite its reliability and high-quality construction, even this chain can exhibit issues over time, especially if installation, maintenance, or compatibility guidelines are overlooked. This guide provides a detailed analysis of the most common problems encountered with the CN-6701 [paid link] chain and offers step-by-step instructions for resolving them.
Chain Skipping Under Load
One of the most frequently reported issues with the CN-6701 [paid link] is chain skipping, particularly under high-torque situations such as climbing or sprinting. This issue typically arises from one of three causes: chain wear, cassette wear, or improper chain length.
Check the chain for stretch using a chain checker tool. The CN-6701, like other Shimano 10-speed chains, has a recommended wear limit of 0.75%. If the chain exceeds this, replace it promptly to prevent damage to the cassette. Equally important is to inspect the cassette cogs for wear patterns or shark-tooth profiles that may no longer engage properly with a new or moderately worn chain.
Another overlooked factor is chain length. An improperly sized CN-6701—especially one that is too short—can create undue tension, leading to poor engagement and skipping. Ensure the chain is installed with the correct number of links for your specific drivetrain configuration.
Inconsistent Shifting Performance
Erratic or sluggish shifting is another common concern associated with this chain. Unlike general-purpose chains, the CN-6701 is engineered with an asymmetrical plate design to improve front and rear shifting. However, if installed backward, the shifting performance degrades significantly.
Verify that the chain has been installed with the correct orientation. The outer plates of the CN-6701 are marked, and the logo should face outward (visible from the drivetrain side). Installing the chain with the logo facing inward can cause poor shift engagement.
Additionally, check for derailleur alignment. Even a slightly bent derailleur hanger can lead to imprecise shifts. Shimano recommends periodic hanger alignment checks, especially after crashes or transport. Cable tension, worn jockey wheels, and gummed-up housing can also contribute to inconsistent shifts.
Drivetrain Noise and Rattling
Unusual noise from the drivetrain while pedaling is another symptom that may point to issues with the CN-6701 chain. Often, this is not a defect in the chain itself but rather a sign of contamination or insufficient lubrication.
The CN-6701 features a PTFE surface treatment to reduce friction, but this benefit is negated if the chain is dirty or dry. Regular cleaning using a degreaser followed by lubrication with a Shimano-approved wet or dry lube [paid link] can restore quiet performance. When lubricating, always wipe off excess oil to prevent dirt accumulation.
Misalignment due to cross-chaining (e.g., large chainring to large cog or small-to-small) may also cause rattling. Ensure proper gear combinations are used and limit cross-chaining to avoid unnecessary strain and noise.
Chain Drop During Shifting
Chain drops are disruptive and potentially dangerous during rides. The CN-6701’s design minimizes this risk, but improper front derailleur setup or chainring wear can still cause drops.
Ensure the front derailleur cage is properly aligned and set to the manufacturer’s recommended height and angle. The outer cage plate should run parallel to the chainrings, and the height should be 1-3 mm above the large ring teeth. Chainring inspection is also crucial. Worn or damaged teeth can fail to guide the chain accurately during shifts.
Moreover, if the chain has been cut too short, it may lack the slack necessary for smooth front shifts, increasing the likelihood of chain drops under load.
Chain Sticking or Binding Links
Stiff links are another commonly encountered issue, especially after initial installation or pin insertion. The Shimano CN-6701 chain uses a special connecting pin that must be inserted and snapped off correctly.
If a link feels stiff or does not articulate freely, it could be due to improper pin installation. Gently flex the chain laterally at the stiff link to loosen it. If this does not solve the issue, inspect for any visible misalignment or deformation. Reinstalling the connecting pin or using a Shimano Quick Link (SM-CN10) may resolve this problem more reliably.
Persistent binding may also indicate internal corrosion, typically resulting from inadequate maintenance. Regular cleaning and lubrication are essential to keep the linkages moving smoothly and prevent rust.