The Bicycling Thread

[wildbears]

Loose B-Screw

The causes the rear derailleur to rattle and suggests that the "trim" is off. It has happened several times on my 105 R7100 group set.

A rear derailleur B-screw loosening on its own is typically caused by vibrations overcoming the light spring tension, a damaged or worn screw thread, or the screw not resting securely against the hanger tab. Apply a small amount of low-strength Loctite 222 (purple) to the threads to secure it while still allowing future adjustments.

Common Reasons and Fixes

• Vibration/Lack of Thread Friction: Use Loctite 222 (purple), nail polish, or light super glue on the threads.
• Worn Threads/Hanger Tab: If the hole is stripped or the derailleur hanger tab is damaged, the screw won't hold. A new derailleur hanger may be required.
• Wrong Position: Ensure the screw is resting properly on the tab of the derailleur hanger.
• Chain Length: If the chain is too long, the derailleur cage can sit in a position that reduces tension on the B-screw.

If you are adjusting your derailleur B screw, it is recommended to adjust the B screw while holding the derailleur body back to reduce tension on the screw.

The B-screw acts as a solid limit screw, designed to be adjusted against the derailleur hanger tab to set the gap between the upper pulley wheel and the cassette.

• Function: It adjusts the B-gap/tension, allowing the derailleur to clear the largest cog.
• Design: On the R7100, it is a simple, direct-contact screw rather than a spring-loaded tensioning screw, as modern Shimano derailleurs utilize a different design to handle wider gear ranges.

[955i]

I am a master at turning the adjustment screws the WRONG way. I end up worse and the have to slowly earn my way back. If I'm lucky, I can sorta adjust it within "tolerable tolerances."

[wildbears]

Couldn't find Loctite 222 locally so going with nail polish.

[wildbears]

If you are adjusting your derailleur B screw, it is recommended to adjust the screw while holding the derailleur body back to reduce tension on the screw.

[wildbears]

[955i]

Another gear "or two" going uphill.

[wildbears]

Obesity and PGAD:

Obesity is associated with the stretching and relaxation of the perineum, a condition often called perineal descent or bulging. The excess weight causes chronic, increased pressure on the pelvic floor muscles, which can damage the tissues and cause the pelvic area to sag or drop. This can result in increased irritation of the perineal nerves by the saddle. Besides weight loss, there are a number of ergonomic bicycle adjustments that can help

[wildbears]

The Worst Times to Ride a Bicycle and Maybe a Motorcycle....

The worst time of day to ride a bicycle is generally during weekday afternoon rush hour (roughly 5:00 PM to 7:00 PM), which is statistically the most dangerous due to high traffic volume, stressed drivers, and poor visibility. Early morning commuting hours (7:00 AM to 9:00 AM) and midnight to early morning hours are also hazardous due to impaired drivers. [1, 2, 3, 4, 5]

Worst Times and Reasons

• Weekday Afternoon Rush Hour (3:00 PM – 7:00 PM): This is the peak time for accidents, with one study finding the highest fatalities between 3-6 PM. Drivers are often tired, stressed, and in a hurry.
• Nighttime (6:00 PM – 6:00 AM): Nearly one-third of fatal bicycle crashes with motor vehicles occur at night due to poor visibility, even with lights.
• Dusk/Dawn: Known as a high-risk time because of rapidly changing light conditions, making it hard for drivers to see cyclists, especially when drivers forget to turn on their headlights.
• Mid-Day in Summer: While traffic may be lighter than rush hour, this is when temperatures are highest, creating risks of overheating and, in urban areas, poor air quality. [1, 2, 3, 4, 5]

Key Safety Precautions

• If you must ride at these times, ensure you are visible by using bright lights and wearing reflective gear. [1]
• Avoid: Friday afternoons (high congestion/impaired driving).
• Alternative: Weekend mornings (6 AM–Noon) are considered some of the safest times. [1, 2]

[955i]

Statistics show that another really bad time to ride is after 4-5 margaritas and a couple of beers.

[wildbears]

But not if you ride a Harley Davidson....