The Shimano CN-HG71 [paid link] chain is a staple in the world of reliable and performance-oriented bike components. Designed primarily for 6, 7, and 8-speed drivetrains, it has become a go-to choice for cyclists who prioritize efficiency and durability. However, even the best chains can produce noisy shifting if not properly installed or maintained. This guide explains how to diagnose and fix noisy shifting specifically related to your CN-HG71 [paid link] chain, ensuring a smoother and quieter ride.
Understanding Noisy Shifting on the CN-HG71 Chain
Noisy shifting is often a symptom of improper chain installation, poor maintenance, or drivetrain component mismatch. With the CN-HG71 [paid link], the chain’s design is optimized for smooth transitions across cogs, but several factors can interfere with its performance. Understanding these root causes is essential before diving into any adjustments or fixes.
Noise can manifest as a clicking, clattering, or grinding sound when shifting between gears. This not only affects ride quality but also hints at potential wear that could shorten the lifespan of your drivetrain. Proper diagnosis is crucial for accurate, efficient corrections.
Common Causes of Noisy Shifting with the CN-HG71
Chain Wear and Stretch
Over time, chains elongate due to wear, a phenomenon commonly referred to as “chain stretch.” The CN-HG71, like any other chain, is susceptible to this, especially if not lubricated regularly. A stretched chain won’t sit properly on cassette teeth, resulting in misalignment and noise during gear changes.
Improper Chain Length
A chain that is either too long or too short disrupts the derailleur’s tension balance. The CN-HG71 must be sized accurately during installation. Incorrect length leads to poor chain tension, contributing to sluggish or noisy shifts.
Dirty or Dry Chain
Contaminants like dirt, dust, and old lubricant can compromise the CN-HG71’s smooth operation. A dirty chain increases friction, while a dry chain leads to metal-on-metal contact noises.
Derailleur Misalignment
Even though the CN-HG71 is designed for reliable shifting, it cannot compensate for a poorly aligned derailleur. Misalignment causes the chain to hesitate or grind when shifting, amplifying operational noise.
Cassette and Chainring Wear
The CN-HG71’s performance heavily depends on the condition of the cassette and chainrings. Worn teeth prevent proper engagement, leading to skipping and noise, particularly under load.
Inadequate Lubrication
The CN-HG71 is engineered to perform with minimal friction, but inadequate or incorrect lubrication negates this advantage. Dry or incorrectly lubricated chains produce squeaking and rattling sounds, especially under shifting stress.
Diagnosing Noisy Shifting: Step-by-Step Guide
Start by methodically checking each potential source of noise to isolate the problem.
1. Visual Inspection
Inspect the CN-HG71 chain for signs of wear, rust, or contamination. Look for stiff or kinked links that can impede smooth operation. Check if the chain hangs loosely or sags excessively, which could indicate stretch.
2. Chain Stretch Measurement
Use a chain checker tool to measure elongation. Shimano recommends replacing chains when they reach 0.75% stretch. A stretched CN-HG71 compromises shift quality and increases drivetrain wear.
3. Confirm Chain Length
Ensure the chain length was set correctly during installation. For the CN-HG71, route the chain through the derailleur and check for appropriate tension. A quick method involves wrapping the chain around the largest chainring and largest sprocket without the derailleur, then adding two full links.
4. Cleanliness Check
Assess the chain’s cleanliness. If grime buildup is evident, a thorough degreasing followed by proper lubrication is necessary. Even high-performance chains like the CN-HG71 cannot function well when coated with dirt.
5. Derailleur Alignment Test
Check the derailleur hanger alignment using a derailleur alignment gauge. A bent hanger can cause poor indexing, resulting in shifting noise.
6. Cassette and Chainring Examination
Inspect for worn or broken teeth on the cassette and chainrings. If the cassette teeth appear shark-fin shaped or chainrings are excessively worn, they must be replaced to restore smooth shifting.
7. Lubrication Assessment
Evaluate the chain’s lubrication. The CN-HG71 benefits from light, penetrating chain lube. Over-lubrication can attract debris, while under-lubrication increases friction.
How to Fix Noisy Shifting on the CN-HG71 Chain
Once the cause is identified, take corrective measures specific to your diagnosis.
Replace a Worn or Stretched Chain
If the CN-HG71 exceeds 0.75% wear, replace it promptly. Continuing to ride on a worn chain can accelerate wear on other drivetrain components, making the repair more costly.
Adjust Chain Length
For an incorrectly sized chain, remove or add links as necessary. Always ensure proper chain tension to promote optimal shifting performance.
Deep Cleaning and Lubrication
Degrease the chain thoroughly using a biodegradable chain cleaner. After drying, apply a quality chain lubricant, ensuring it penetrates the rollers. Wipe off excess lube to prevent grime accumulation.
Correct Derailleur Alignment
Use the derailleur hanger alignment tool to straighten any bends. After alignment, adjust the derailleur’s high and low limit screws and indexing to ensure precise gear changes.
Replace Worn Cassette or Chainrings
If cassette or chainring wear is found, replacement is mandatory. Pairing a new CN-HG71 chain with worn gears will result in continued poor shifting and additional noise.
Proper Lubrication Practices
Establish a regular maintenance routine. Lubricate the CN-HG71 after every few rides, especially after wet conditions, to maintain quiet, smooth operation.
Preventing Noisy Shifting on the CN-HG71
Prevention is key to maintaining the CN-HG71’s legendary performance. Regular maintenance, timely chain replacement, and careful installation practices will minimize the chance of noisy shifting. Adopting a monthly inspection routine can help catch early signs of wear or misalignment, preserving both your chain and overall drivetrain.