The Shimano CN-6800 [paid link] chain, part of the Ultegra 11-speed groupset, is designed for high-efficiency power transfer, smooth shifting, and durable performance. However, even top-tier chains like the CN-6800 [paid link] can experience issues if not properly installed or maintained. This guide explores the most common problems associated with the CN-6800 [paid link] chain and provides clear, technical solutions to restore optimal function.
Common Shifting Hesitations and Chain Skipping
A frequently reported issue with the CN-6800 chain is hesitant shifting or chain skipping, particularly under load. These symptoms often point to chain wear or improper chain length. When the chain is elongated beyond acceptable tolerances, it no longer meshes correctly with the cassette or chainrings. Similarly, a chain that is too short can create excessive tension, while an overly long chain can cause slack and inconsistent engagement.
To address this, verify the chain length by wrapping it around the largest chainring and largest cog, bypassing the derailleur. Add two full links (one inner and one outer) for the correct length. If the chain exceeds this by more than one link, it should be shortened or replaced. Additionally, inspect for measurable wear using a chain checker tool. If elongation exceeds 0.5% for 11-speed systems, replacement is recommended.
Noisy Chain in the Middle Gears
The CN-6800 may produce noticeable drivetrain noise when running in the mid-range gears. While noise can stem from many sources, this particular pattern often results from improper derailleur adjustment or a dirty chain interface. Misalignment in the derailleur hanger or cable tension can cause the jockey wheels to deviate slightly, leading to poor indexing.
Begin by confirming derailleur hanger alignment using a gauge tool. Then, fine-tune cable tension with the barrel adjuster to ensure the chain sits perfectly centered on each cog. If indexing is precise yet noise persists, a deep cleaning may be necessary. Remove the chain and degrease it thoroughly. Re-lubricate with a high-quality chain lube suited to your riding conditions, ensuring the lubricant penetrates between the rollers and inner plates before wiping off any excess.
Chain Drop During Front Shifts
Front shifting issues, especially chain drop from the inner chainring, are another common concern. This often results from poor front derailleur positioning or worn chainring teeth. The Shimano CN-6800 chain’s narrow profile requires accurate derailleur height and alignment to function correctly.
Ensure the front derailleur cage sits 1-2mm above the tallest chainring tooth and that it is parallel to the chainring. Adjust the high and low limit screws to restrict the derailleur’s movement to only what is necessary for smooth gear transitions. If the teeth on the chainring appear hooked or excessively worn, replacement may be necessary, as even a new chain cannot compensate for uneven tooth profiles.
Sluggish Shifting Under Load
Shifting under heavy pedal load can be problematic with the CN-6800 chain if the chain is inadequately lubricated or the cassette and chainring interfaces are worn. The CN-6800’s inner and outer plate design is optimized for quick engagement, but contamination or wear can impair this function.
Clean the drivetrain thoroughly and inspect the cassette and chainrings for wear patterns or burrs. Apply lubricant to the chain only after it has been cleaned and dried. Choose a lube that matches your environmental conditions (wet or dry) and ensure that it does not attract dirt or degrade quickly. In the case of worn components, synchronizing replacement of the chain, cassette, and chainrings is often the best long-term solution to restore crisp shifting.
Unusual Chain Noise in Low Gears
Low gear operation may sometimes result in grinding or clicking sounds when using the CN-6800 chain. This can be due to excessive cross-chaining, where the chain is at an extreme angle between the large chainring and large cog, or small chainring and small cog.
Minimize cross-chaining by selecting appropriate gear combinations that keep the chainline as straight as possible. If noise persists even with a good chainline, check the rear derailleur’s B-tension adjustment. The guide pulley should maintain a 5-6mm gap from the largest cog when viewed from the rear. Adjust the B-screw as necessary to correct spacing.
Conclusion
Diagnosing and fixing CN-6800 chain issues requires a systematic approach that includes examining wear, lubrication, alignment, and gear compatibility. Regular maintenance and precise adjustments ensure that the chain operates quietly and shifts smoothly across all gears. Addressing common problems proactively not only restores performance but also extends the life of the entire drivetrain.