The Shimano CN-HG71 [paid link] chain has earned a reputation for being a reliable and efficient component for 6, 7, and 8-speed drivetrains. Known for its robust construction and smooth shifting performance, it is a go-to choice for many road cyclists. However, like any chain, the CN-HG71 [paid link] is not immune to issues that can affect its function and longevity. In this guide, we delve into the most common problems encountered with the CN-HG71 [paid link] chain and provide detailed, expert solutions to keep your drivetrain running smoothly.
Chain Stretch and Premature Wear
Chain stretch, more accurately referred to as elongation, is one of the primary concerns with any bicycle chain, including the CN-HG71. As the chain wears, the distance between the links increases, leading to poor shifting and accelerated wear on your cassette and chainrings.
Several factors can contribute to chain stretch:
- Insufficient lubrication
- Frequent riding in muddy or gritty conditions
- Delayed chain replacement schedules
Solution:
Regular measurement using a chain wear indicator tool is essential. Shimano recommends replacing the chain when elongation reaches 0.75%. Cleaning and lubricating the chain every 150-200 miles, or after riding in wet conditions, can significantly slow down wear. Opt for a high-quality, bike-specific lubricant suited to your typical riding environment.
Skipping Under Load
A chain that skips during heavy pedaling or uphill climbs can be both annoying and dangerous. Skipping usually points to a worn chain, a worn cassette, or improper chain length.
Solution:
First, inspect the chain for wear using a dedicated tool. If the chain is within acceptable limits but skipping persists, examine the cassette teeth for shark-fin shapes or uneven wear. If both the chain and cassette show signs of wear, replacing them together is often necessary. For the CN-HG71, ensuring correct chain length during installation is critical. A proper length check involves wrapping the chain around the largest chainring and largest rear sprocket without going through the derailleur, then adding two full links.
Poor Shifting Performance
Shifting that feels sluggish or inaccurate can arise from several issues:
- Chain contamination
- Incorrect installation
- Incompatibility with other drivetrain components
Solution:
Start with a deep cleaning of the chain using a degreaser and a chain scrubber tool. Ensure the chain is properly routed through the derailleur pulleys and that the quick link or connecting pin was correctly installed. The CN-HG71 is designed for HG and IG drivetrains; pairing it with non-compatible systems could cause poor shifting. Always verify compatibility before installation.
Chain Noise
Unusual noises, such as clicking or grinding, are common symptoms of chain issues. Causes include misalignment, improper lubrication, or a chain that is too long or too short.
Solution:
Check the derailleur adjustment to ensure proper alignment with the cogs. Lubricate the chain thoroughly and allow excess lubricant to drip off to prevent dirt accumulation. Inspect the chain length again, following Shimano’s sizing recommendations. A correctly sized and lubricated CN-HG71 should run nearly silent under proper adjustment.
Rust and Corrosion
Although the CN-HG71 features a durable zinc-alloy plating designed to resist rust, neglecting chain care can lead to corrosion, especially in humid or salty environments.
Solution:
Wipe down the chain after rides in wet conditions and apply a thin coat of lubricant to all chain links. For severe rust, removal and soaking in a rust-dissolving solution may restore some function, but often replacement is the safest option. Storage in a dry environment and consistent maintenance are key to preventing corrosion.
Stiff Links
Stiff links can disrupt smooth chain motion, causing hesitation in shifting or an inconsistent pedaling feel. They are often the result of improper pin installation or chain contamination.
Solution:
Manually flex the affected link side-to-side to loosen it. If the stiffness persists, inspect whether the connecting pin was inserted correctly. For the CN-HG71, Shimano recommends using a replacement pin specifically designed for 7- and 8-speed chains to ensure a secure but flexible connection. If using a quick link, ensure it is correctly seated and fully snapped into place.
Chain Drop
Dropping the chain from the chainring, especially during shifts from large to small rings, is another common issue.
Solution:
Ensure the front derailleur is properly adjusted with the correct limit screw settings to prevent overshifting. Chainrings should be inspected for wear, as worn teeth can make it easier for the chain to slip off. The CN-HG71’s Hyperglide design optimizes shifting, but it still requires precise derailleur adjustment to function optimally.
Conclusion
While the Shimano CN-HG71 chain is built for dependable performance, it requires regular attention and proper installation to avoid common issues. Regular maintenance—cleaning, lubricating, and monitoring wear—combined with correct setup practices will ensure your CN-HG71 provides smooth, efficient service for many miles. Addressing problems promptly not only restores performance but also extends the life of your entire drivetrain.