Recent content by zerodish

  1. Z

    My model of bicycle spokes breaking

    There was about 40 mm between the dropout and the inside of the cone on the standard 5 cog freewheel sold in the 70's Then the industry went mad. Jack Taylor's words not mine. The Modern 7 cog freewheel sold in depertments increased the moment arm to 47.5. mm Meanwhile secular trends in human...
  2. Z

    My model of bicycle spokes breaking

    I volunteer in the coops. I had a customer come in who had broke 8 spokes on a single ride. I have no idea how far the ride was but if he had used 14 gauge instead of 15 gauge he would have broken 1/5 as many spokes. A much safer ride. I tour and keep the rear rack loaded even when I'm not...
  3. Z

    My model of bicycle spokes breaking

    The following equation comes from a paper by HP Gavin. LOG(stress)=-.3LOG(cycles)=4.12+.072Z where Z is the normal distribution. If you only have 1 spoke you place it in the middle of the normal distribution that is a Z score of 0. So if you have 36 spokes you divide the normal distribution into...
  4. Z

    Stress riser in a bicycle rim.

    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...
  5. Z

    The Joy of X: Solving the Hilbert Hotel Question with Steven Strogatz

    Hilbert's hotel is a fallacy. The problem is there is always some one in the hallway. To convince yourself this is true try to check into Ramsey's hotel. Ramsey's hotel has a hallway with a finite size. It connects to an infinite number of rooms in an infinite number of dimensions. Move some one...
  6. Z

    Did a Shear-Tensile Failure Cause the Wire Rope Accident?

    Here is the photo you can view it on flickr by searching "national electrical code" in quotes.
  7. Z

    Did a Shear-Tensile Failure Cause the Wire Rope Accident?

    I have been photographing wires hanging from utility poles that have tangled with and caused automobile accidents. One of these is a puzzle the detail shows a wire from a 7 strand wire rope made out of aluminum. It was too dangerous at the time to anything but drag the wire out of the road and...
  8. Z

    Any one have a diagram of the idea column shape.

    Sorry I can't find the article it had the diagram. The idea hyperbolic flywheel shape is easy to find on the web http://www.sciencedirect.com/science/article/pii/S0360544211005251 the column shape should be easier to find since columns are much more common than flywheels. I'm replacing all the...
  9. Z

    Any one have a diagram of the idea column shape.

    It ran in Science News after much calculation the idea shape for a column to resist buckling was solved. It is a slight barrel shape.
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