The Shimano CS-6700 [paid link] cassette, part of the Ultegra 6700 groupset, is engineered for high-precision, smooth-shifting performance. However, over time or due to incorrect setup, you might notice unwanted noise during shifting. This guide walks through the diagnostic steps and effective fixes to restore silence and smoothness to your drivetrain.
Understanding CS-6700 [paid link]-Specific Shifting Noise
Shifting noise in the CS-6700 [paid link] often stems from alignment issues, wear, or compatibility mismatches. Unlike more recent cassettes with refined tooth profiles and coatings, the CS-6700 demands accurate setup and regular attention to maintain optimal performance. Even minor errors can lead to amplified noise through the drivetrain under load.
Inspecting Cassette Installation for Noise Sources
Improper installation is a primary cause of noise in the CS-6700 cassette. Begin by checking that the cassette lockring is fully torqued to Shimano’s recommended 40 Nm specification. If under-torqued, the cogs may move under pedaling load, resulting in creaking or clicking sounds.
Next, confirm that the individual sprockets and spacers are correctly ordered and seated on the freehub body. A misplaced or missing spacer — particularly between the last sprockets — will lead to inconsistent cog spacing, causing the chain to ride awkwardly and noisily between gears.
Also inspect the freehub body itself. If the splines are gouged or worn, the cassette may not sit flush, producing uneven engagement and resulting in shifting rattle or skipping.
Indexing and Derailleur Alignment
Even with a properly mounted CS-6700 cassette, poor indexing or derailleur alignment can be the culprit. This model’s sprocket profile was designed around 10-speed systems with tight gear spacing, meaning indexing precision is critical.
Verify cable tension and re-index the rear derailleur if necessary. In particular, check the B-tension screw — an incorrect distance between the top jockey pulley and the cassette will affect how quietly the chain moves between gears.
A bent derailleur hanger can also cause noisy shifts. Use a derailleur alignment tool to measure and straighten the hanger, ensuring the derailleur cage tracks precisely beneath each sprocket.
Chain Compatibility and Condition
The CS-6700 cassette was designed for 10-speed Shimano HG chains. Using wider or narrower chains, or worn-out chains, can introduce unwanted noise. Always measure chain wear with a chain checker and replace once elongation exceeds 0.75%. A stretched chain will fail to sit properly on the cog teeth, leading to skipping and noise under load.
If your drivetrain uses a mixed-brand setup, be cautious: even slight deviations in chain width or plate shape can increase friction and noise on the CS-6700.
Cleaning and Lubrication Practices
Dirt and old lube buildup are often overlooked sources of shifting noise. The CS-6700’s narrower spacing between sprockets can trap grime more easily, affecting shift quality.
Regularly degrease the cassette using a cassette brush or cleaning tool to remove hardened debris. After drying, apply a suitable chain lube and allow it to penetrate before wiping off excess. An over-lubed drivetrain can attract dirt, while an under-lubed one increases friction—both generate noise.
Worn Cassette or Chainrings
Over time, the sprocket teeth on the CS-6700 will wear into hooked or pointed shapes, causing the chain to climb or drop awkwardly, especially under load. If you hear clicking or popping under pressure, inspect each cog closely. Compare wear between high-use cogs (like 17T or 19T) and less-used ones.
Also inspect your chainrings. A worn front chainring can introduce harmonics and noise that mimic rear cassette problems. Ideally, replace cassette, chain, and chainrings as a set to maintain optimal engagement across components.
Noise from External Factors
Sometimes, noise assumed to be from the CS-6700 cassette originates elsewhere. Loose spokes, a dry chain, or poorly torqued rear axle can all create resonance that appears to come from the cassette area. Systematically check each drivetrain and wheel component to eliminate unrelated sources before concluding the cassette is at fault.
When to Replace the CS-6700 Cassette
If, after checking all the above, your CS-6700 cassette continues to produce noise despite proper setup, cleaning, and indexing, it may simply be worn beyond service. Look for shark-fin teeth, shiny contact surfaces, or repeated poor shifting on the same gears. These signs indicate the cassette no longer meshes properly with the chain.
FAQs
1. What tools do I need to inspect or remove the CS-6700 cassette?
You’ll need a Shimano-compatible cassette lockring tool [paid link], a chain whip, a torque wrench [paid link], and ideally, a derailleur alignment gauge for complete diagnostics.
2. Why does my CS-6700 make noise only in certain gears?
This usually points to sprocket wear or improper cable tension. Gear-specific noise often indicates localized wear on specific cogs.
3. Can I use an 11-speed chain with the CS-6700 cassette?
No. The 11-speed chain is narrower and not optimized for the 10-speed spacing of the CS-6700. This mismatch often results in noisy, imprecise shifting.
4. How often should I clean the CS-6700 cassette?
Clean it every 200–300 miles under normal conditions, or more frequently in wet or gritty environments to avoid buildup that causes noise.
5. Is a loud CS-6700 cassette dangerous?
While not inherently dangerous, excessive drivetrain noise indicates mechanical inefficiency, potential wear, or misalignment that can lead to more serious drivetrain issues.
6. How can I tell if the cassette spacers are correct?
Count the number of spacers and check their placement against Shimano’s CS-6700 documentation. Incorrect spacer arrangement will lead to uneven cog spacing and shifting noise.
Conclusion
Noisy shifting on the Shimano CS-6700 cassette can stem from a range of causes, from installation errors to wear and dirt buildup. By systematically checking each potential issue—from cassette torque to derailleur alignment and chain wear—you can identify and resolve the root cause effectively. Maintaining cleanliness and ensuring compatibility with chains and drivetrain components will preserve your CS-6700’s precise, quiet shifting performance for many miles to come.