The Most Common CS-6700 Cassette Problems and How to Solve Them

The Shimano CS-6700 [paid link] cassette is a component from the Ultegra 6700 series, a trusted name in mid-to-high-end road cycling drivetrains. Built for 10-speed systems, the CS-6700 [paid link] strikes a balance between performance, weight, and durability. However, like all drivetrain components, it is subject to wear, setup errors, and compatibility challenges. This article explores the most frequent problems cyclists experience with the CS-6700 [paid link] cassette and provides detailed, actionable solutions for each issue.

Unreliable or Inconsistent Shifting

One of the most commonly reported issues with the CS-6700 cassette is inconsistent shifting across the 10-speed range. Riders may experience delays in gear engagement, overshooting gears, or loud shifts.

This issue often stems from cable tension that is either too tight or too loose, derailleur misalignment, or a worn chain. As the CS-6700 relies on precise spacing between sprockets, even slight deviations can disrupt performance.

Solution:

Begin by inspecting cable tension. Use the barrel adjuster to fine-tune tension while shifting through all gears.
Check rear derailleur alignment with a derailleur hanger alignment tool.
Ensure the chain is not excessively worn using a chain checker. Replace it if elongation exceeds 0.75%.
Clean and lubricate the chain and cassette to ensure smooth operation.

Skipping Under Load

Another problem occurs when the CS-6700 skips under high torque, such as during climbs or sprints. Skipping is not only annoying—it can be dangerous and accelerate drivetrain wear.

Often, this is due to mismatched wear between the cassette and the chain. A new chain on a worn cassette, or vice versa, can lead to poor meshing between the chain rollers and the cog teeth.

Solution:

Replace both the chain and cassette at the same time if either is worn.
Inspect the cassette teeth for shark-fin profiles or polished points—these are signs of wear.
Always use Shimano-recommended chain models like CN-6701 [paid link] for best compatibility.

Excessive Noise from the Cassette Area

Noise issues, such as rattling or grinding, can originate from multiple sources around the cassette. In the case of the CS-6700, common culprits include loose lockrings, dry hub interfaces, or improperly torqued components.

Solution:

Check that the cassette lockring is torqued to Shimano’s specification of 40 Nm using a torque wrench [paid link].
Remove the cassette and clean the freehub body and spacer rings.
Apply a thin layer of grease to the freehub splines before reinstalling the cassette to reduce creaking.

Shifting Too Fast or Too Slow Between Gears

Sometimes, the CS-6700 may feel jumpy when changing gears, either shifting too quickly or hesitating between sprockets. While this can often be traced to cable drag, it’s also influenced by derailleur settings and chain length.

Solution:

Replace old or contaminated cables and housing to reduce friction.
Re-index the rear derailleur carefully using the barrel adjuster.
Verify the chain length using Shimano’s “big-big” method—wrap the chain around the largest chainring and sprocket without routing through the derailleur, then add two full links.

Cassette Cogs Getting Stuck or Seized

In rare cases, individual sprockets on the CS-6700 can bind to the freehub body, especially if there is corrosion or if the cassette hasn’t been removed for extended periods.

Solution:

Use anti-seize compound or grease on the cassette threads and spline surfaces during installation.
Periodically remove and inspect the cassette, especially if the bike is ridden in wet or dirty conditions.

Compatibility Problems with Other Drivetrain Components

Some riders encounter issues when using the CS-6700 with non-Ultegra components. While Shimano 10-speed systems are largely cross-compatible, pairing with incompatible chains or derailleurs can impair performance.

Solution:

Use only 10-speed Shimano-compatible chains and derailleurs.
Avoid mixing with SRAM or Campagnolo 10-speed systems, which use different cog spacing and actuation ratios.

Cassette Slippage on the Freehub

A rare but significant issue involves the entire cassette rotating or slipping independently of the freehub under torque. This typically results from improper lockring torque or incompatible freehub spline profiles.

Solution:

Confirm that the freehub is Shimano 10-speed compatible.
Ensure all spacer rings are installed in the correct order.
Tighten the lockring to the manufacturer’s torque specification using a cassette lockring tool [paid link].

Worn or Deformed Spacer Rings

Though often overlooked, spacer rings used between the cassette sprockets can deform or wear over time, especially if torqued incorrectly or reused across multiple cassettes.

Solution:

Inspect all spacers for wear or flattening.
Always reinstall spacers in the original order or replace them with new ones during cassette installation.

Corrosion on Cassette Teeth

Even with anodized finishes, the steel sprockets on the CS-6700 can rust, especially in humid or coastal environments or after riding in the rain without cleaning.

Solution:

Clean the cassette regularly and dry thoroughly after wet rides.
Apply a light oil coating to prevent rust when storing the bike for extended periods.

Loose Sprockets Causing Rattle or Shift Delay

Individual sprockets that are not seated correctly can shift during use, leading to noise or hesitation in gear transitions.

Solution:

Reinstall the cassette and confirm proper orientation and seating of each sprocket.
Replace worn or damaged spline interfaces and spacers.

Conclusion

The CS-6700 cassette is a high-performing, reliable component when properly maintained. Most issues stem from wear, improper installation, or incompatible drivetrain setups. With regular inspection, appropriate tools, and attention to detail, cyclists can ensure their CS-6700 delivers smooth, quiet, and precise shifting throughout its service life.