Did the CPSC-Mandated Groove Cause Rim Failure?

In summary, the CPSC has mandated a groove on bicycle rims to indicate wear and prevent catastrophic failure. However, a user has found that the mandated groove may actually be causing the failure it is designed to prevent. The user has contacted the CPSC and provided evidence, but they have not responded. The user is seeking input from the community on whether the groove caused the failure or if other factors such as improper spoke tightening or overloading may have contributed.
  • #1
zerodish
9
1
The CPSC has mandated every bicycle rim have a groove to indicate the wear on the rim. I have tested wheels extensively that I built over 100000 miles. As they wear from the brake pads the side walls will bulge from fatigue. If you are paying attention you can feel the brake grab at this spot. It is then time to replace the rim otherwise there will be a catastrophic failure. It seems to me the stress riser mandated by the CPSC is causing the very type of failure the groove is designed to prevent. I contacted them explained to them they were going to be sued and they refused to comment on the issue other than giving me the link saferproducts.gov The photo link is a rim that I put 6000 miles on and it did bulge. I have found under similar conditions a similar rim will last 8000 miles and a rim with the same construction made out of 6061 aluminum will last 16000 miles. I tested one rim to failure an Araya VP 20 which has the same construction shown but is 1mm wider. This rim was never used as a brake and it bulged from fatigue only at 20000 miles. I just need a yes or no from this community. Did this groove cause this failure? https://flic.kr/p/FjwWXW
 
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  • #2
No. A circumferential groove shouldn't be that much of a stress riser. Note the direction of the failure and the big, threaded hole in the rim. That's more suspect than a small circumferential groove. Were the spokes properly tightened? Was the rim overloaded? Did you hit a curb (or, over a period of time, a number of impacts to the rim)?
 
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FAQ: Did the CPSC-Mandated Groove Cause Rim Failure?

What is a stress riser in a bicycle rim?

A stress riser is a point of weakness or vulnerability in a bicycle rim where stress is concentrated, making it more prone to failure or damage.

How does a stress riser occur in a bicycle rim?

A stress riser can occur due to various factors such as manufacturing defects, material flaws, or excessive loading on the rim. It can also be caused by repeated stress and strain on the rim over time.

What are the effects of a stress riser on a bicycle rim?

A stress riser can lead to cracks, fractures, or even complete failure of the rim. This can result in a dangerous and potentially hazardous situation for the rider, as it can cause loss of control or accidents.

How can a stress riser in a bicycle rim be detected?

A stress riser can be detected through visual inspection of the rim, looking for any signs of cracks, dents, or deformities. It can also be detected through the use of non-destructive testing methods such as ultrasonic or x-ray testing.

How can a stress riser in a bicycle rim be prevented?

To prevent a stress riser in a bicycle rim, it is important to use high-quality materials and proper manufacturing techniques. Regular maintenance and inspection of the rim can also help detect and prevent stress risers. Avoiding excessive loading and overloading of the rim can also help prevent stress risers from occurring.

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