Shimano 105 Rear Won't Shift at All: Common Causes and Fixes

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When it comes to bicycle maintenance, few components are as vital as the rear derailleur, and if you're facing the issue of your Shimano 105 rear not shifting at all, it's crucial to act promptly. Whether you're a seasoned cyclist or someone new to biking, understanding the common causes and fixes for this problem can ensure you get back on the road swiftly. The Shimano 105 line is known for its reliability and performance, but like all mechanical systems, they can run into challenges that may hamper your cycling experience.

In this comprehensive guide, we will delve into the heart of the Shimano 105 rear derailleur, exploring the typical symptoms of shifting issues while providing practical solutions. You will learn diagnostic methods, including the insightful Bowstring Test, as well as how to analyze your cable and housing conditions. After establishing the reasons why your derailleur may not be shifting properly, we will highlight quick fixes and essential maintenance tips that will help you keep your system in optimal condition. Let's get started!

Understanding the Shimano 105 Rear Derailleur

The Shimano 105 rear derailleur is an essential component of your bike’s shifting system, responsible for moving the chain between gears. This model is designed to provide smooth and precise gear changes, making it a popular choice among both amateur and serious cyclists. It operates in conjunction with your bike's shifters to allow seamless shifting across a range of gears. However, like all mechanical systems, it requires regular maintenance and an understanding of common issues that can arise.

Functionality of the Shimano 105 Rear Derailleur

The rear derailleur works by adjusting the tension of the chain and positioning it onto the desired sprocket. This is achieved through cables and housing that transmit the motion initiated by the t shifter at the handlebars. It's crucial to keep this system in good condition to avoid issues that can hinder performance.

Common Symptoms of Shifting Issues

Before diving into repairs, it’s important to recognize the signs that indicate your Shimano 105 rear might not be functioning as it should. Common symptoms of shifting issues include:

• No movement at the derailleur when shifting
• Slow or sticky shifting response
• Chain skipping or failing to engage the sprockets
• Excessive force needed for shifting

Quick Diagnostic: The Bowstring Test

Before disassembling anything, a simple and effective diagnostic is the Bowstring Test. This test involves pulling the cable away from the downtube like a bowstring:

• If the cable comes away easily without any reaction at the back, it indicates a broken cable.
• If normal shifting occurs when the cable is tugged, the issue lies within the lever or housing.
• If the shifting feels sticky, there may be friction within the rear derailleur or a buildup in the housing loop.
• If you find that excessive cable movement is required for shifting, it could be a sign of housing deterioration or a slipped cable at the derailleur.

This diagnostic method is efficient and requires minimal effort. Remember, "an ounce of diagnosis is worth a pound of cure." It allows you to pinpoint the issue without unnecessary dismantling.

Analyzing Cable and Housing Conditions

Once you have conducted the Bowstring Test, it’s essential to check the condition of the cable and housing. A well-maintained cable and housing are key to smooth shifting operations of the Shimano 105 rear derailleur. Look for:

• Fraying or kinks in the cable
• Cracks or wear in the housing
• Improperly sealed ends that may let dirt or moisture in

Identifying a Broken Cable

A broken cable is one of the most common issues affecting the Shimano 105 rear derailleur. If you conducted the Bowstring Test and found that the cable disconnects easily, this is likely. Check if the ends of the cable are frayed or if there are any breaks along its length. If the cable is indeed broken, it will need to be replaced.

Troubleshooting Lever Problems

If your initial test showed that the cable is intact, then the next potential issue might lie in the t shifter itself. Problems with the shifter can manifest in various ways:

• Stiffness when shifting
• Failure to engage with the cable properly
• No feedback when pressing the lever

To troubleshoot this, check if the lever is properly mounted and if there’s any visible damage or foreign debris causing obstructions.

Dealing with Sticky Shifting

Sticky shifting is frustrating and can result from various factors. To diagnose this:

• First, inspect the cable for friction points that could be causing resistance.
• Next, examine the housing for sharp bends or kinks which might be constricting the cable movement.
• Finally, ensure that the rear derailleur pivots are well-lubricated for smooth movement.

Assessing Housing Deterioration

Housing deterioration is another potential cause of shifting problems with the Shimano 105 rear derailleur. Over time, the housing can wear down due to exposure to the elements and constant motion. To assess the housing:

• Look for cracks or scuffs that could impede cable movement.
• Check for splits, as these can affect cable performance significantly.
• Replace any damaged housing to restore optimal shifting performance.

Resolving Slipped Cables at the Derailleur

Sometimes the issue may simply stem from a slipped cable at the derailleur pinch bolt. This can be easily rectified by re-seating the cable in the pinch bolt and ensuring it is tight enough to hold the tension properly. After making these adjustments, re-check the shifting to ensure smooth operation.

Additional Potential Issues to Consider

While most shifting problems can stem from the areas previously mentioned, other minor issues can also cause a lack of shifting functionality. Consider:

• Miscalibration of the derailleur itself
• Issues with the chain such as bends or damage
• Problems with the rear cassette including wear

Quick Fixes and Maintenance Tips

To keep your Shimano 105 rear derailleur functioning at peak performance, implementing regular maintenance checks can save time and frustration. Here are some quick fixes and tips to maintain your system:

1. Regularly inspect and replace cables and housing as needed.
2. Lubricate the moving parts of the derailleur to reduce friction.
3. Clean your derailleurs and cassettes frequently to remove dirt and grime.
4. Ensure your t shifter is functioning properly and calibrate if necessary.
5. Perform a full bike tune-up seasonally to ensure optimal performance.

Conclusion: Keeping Your Shimano 105 in Top Shape

In conclusion, dealing with a Shimano 105 rear that won't shift at all can be a challenging situation for any cyclist. However, by understanding the common causes and fixes outlined in this guide, you can diagnose issues effectively and keep your bike performing at its best. Regular maintenance is key to preventing these issues from arising, and knowing how to address them when they do will not only enhance your cycling experience but ensure long-lasting performance from your Shimano 105 rear derailleur. Stay proactive in your bike's care, and enjoy every ride with confidence!

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