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Stress riser in a bicycle rim.

  1. Apr 9, 2016 #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
     
  2. jcsd
  3. Apr 9, 2016 #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)?
     
    Last edited: Apr 9, 2016
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