Details zu Lochkreismustern bei Kettenblättern: Unterschied zwischen den Versionen

* [https://cdn-0.sheldonbrown.com/images/chainring-dimensions-small.png Eine Seite aus der JIS Norm D 9415, auf der die Kettenblattmaße spezifiziert werden (Website von Sheldon Brown/JPG/English)]

To find the bolt-circle dimensions of a chainring, I copy the manufacturer's photo of it onto a letter-size sheet of paper, as large as I can make it. To confirm that the plane of the camera sensor was parallel to that of the chainring, I find the center -- the intersection of two lines between opposite points on the chainring. This is easy if the chainring has an even number of teeth. Placing a straightedge at the edge of opposing teeth makes for high accuracy. Then I measure the distance out to the bolt holes from the center. If the camera sensor and chainring plane were parallel, radial distances will be the same. Most chainrings have all bolt holes at the same radius, making it possible to take an average. If the differences among measured radii are at all substantial, I reject the photo.