When installed and maintained properly, the Shimano CN-HG71 [paid link] chain delivers reliable performance for road, gravel, and commuter bikes. However, noisy shifting can compromise ride quality and indicate underlying mechanical issues. Understanding the causes and solutions is essential to ensuring smooth, quiet gear changes and prolonging component life. This guide will walk you through diagnosing and fixing noisy shifting specifically related to the CN-HG71 [paid link] chain.
Understanding Noisy Shifting in the CN-HG71 Chain
Noisy shifting typically results from misalignment, improper installation, chain wear, or drivetrain contamination. The CN-HG71 [paid link], designed for 6/7/8-speed systems, demands precise installation and routine maintenance to perform optimally. If the chain is noisy during shifting, it often points to mechanical inefficiencies that need immediate attention.
Identifying the root cause requires a systematic approach, focusing first on the chain, then expanding to other drivetrain components.
Common Causes of Noisy Shifting
Chain Wear and Stretch
Over time, the CN-HG71 chain experiences elongation—commonly referred to as chain stretch. Even minimal stretch can disrupt the interaction between the chain and cassette teeth, leading to poor engagement and audible noise during shifts.
Frequent riding in gritty conditions or neglecting chain lubrication accelerates this wear, making regular inspection vital.
Incorrect Chain Length
An improperly sized CN-HG71 chain affects derailleur tension and cassette engagement. Chains that are too long may sag, while overly short chains can over-tension the derailleur, both leading to harsh, noisy shifting.
Correct chain sizing ensures smooth articulation across all gears without undue strain on components.
Dirty or Contaminated Chain
Dirt, debris, and old lubricant buildup hinder the free movement of chain links and rollers. Contamination increases friction, impeding shift quality and amplifying drivetrain noise.
A neglected CN-HG71 chain will audibly signal the need for cleaning and relubrication.
Derailleur Misalignment
While the focus remains on the CN-HG71 chain, it’s essential to recognize that derailleur alignment directly impacts chain path accuracy. A poorly aligned derailleur complicates chain movement, resulting in mis-shifts and associated noise.
Small adjustments can significantly enhance shifting silence and precision.
Worn Sprockets
Chains and sprockets wear together. An older cassette with new CN-HG71 chain can create compatibility issues, leading to noise and poor shift engagement. The sharper, worn sprocket teeth fail to mesh well with the fresh chain profile.
Inspection and simultaneous replacement, if necessary, can restore quiet, efficient drivetrain operation.
Diagnosing Noisy Shifting Step-by-Step
1. Inspect Chain Wear
Use a chain checker tool to measure elongation. For the CN-HG71, replace the chain if wear exceeds 0.75%. Excessive wear compromises shift quality and may necessitate cassette replacement.
2. Verify Chain Length
Shift into the largest chainring and largest rear cog without passing the derailleur’s capacity. Check for adequate derailleur cage wrap and smooth chain path. Ensure a slight bend at the derailleur pivot without excessive tension.
3. Clean and Lubricate the Chain
Degrease the CN-HG71 chain thoroughly using a quality chain cleaner. Once dry, apply a fresh, appropriate lubricant, wiping off any excess to prevent dirt attraction. Proper lubrication ensures smooth link movement and reduces shifting noise.
4. Check Derailleur Alignment
Using a derailleur hanger alignment tool, verify and correct any misalignment. Even slight misalignments can create cross-chaining issues, accentuating noise.
5. Inspect Sprockets and Chainrings
Look for hooked teeth or uneven wear patterns. If the cassette shows signs of wear, consider replacing it along with the CN-HG71 chain for optimal performance.
How to Fix Noisy Shifting on the CN-HG71 Chain
Once the diagnosis is complete, addressing the root cause systematically ensures lasting results. Begin by replacing a worn chain or adjusting the length if incorrect. Clean and lubricate the chain regularly, ideally every 100-200 miles depending on conditions.
If derailleur alignment issues persist, make fine adjustments to the limit screws and indexing barrel to achieve precise shifting. Should the cassette or chainrings show significant wear, replace them to prevent further noise and drivetrain damage.
Chain maintenance must become a routine task. The CN-HG71 responds well to proper care, maintaining the crisp, silent shifting Shimano is known for.
Preventative Measures to Avoid Noisy Shifting
- Regular Chain Inspection: Check for stretch every 500 miles.
- Consistent Cleaning: Degrease and relubricate after wet rides or every two weeks.
- Proper Installation: Ensure correct chain sizing and tension from the outset.
- Drivetrain Synchronization: Match chain replacements with cassette wear levels.
- Professional Tune-Ups: Annual service helps catch misalignments early.
By adhering to these practices, riders can maximize the performance of their CN-HG71 chain, ensuring smooth, quiet, and efficient shifting ride after ride.