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While bolt-circle diameters vary, the geometry of the tooth circle of all round bicycle chainrings adheres to a fixed pattern, as the pitch of the chain and the diameter of its rollers are the same. The tops of teeth may stand at different heights, but the gaps between teeth are at the same diameter, within tight tolerances, for any chainring with the same number of teeth. The diameter between gaps opposite one another may be calculated based on the dimensional standards, and he correctness of the calculation may be confirmed by measuring an actual chainring with an even number of teeth. I did both and checked with a 1982 Japanese Industrial Standards manual. You may find my calculations in the Microsoft Excel workbook here. And here is the page from the JIS manual. | While bolt-circle diameters vary, the geometry of the tooth circle of all round bicycle chainrings adheres to a fixed pattern, as the pitch of the chain and the diameter of its rollers are the same. The tops of teeth may stand at different heights, but the gaps between teeth are at the same diameter, within tight tolerances, for any chainring with the same number of teeth. The diameter between gaps opposite one another may be calculated based on the dimensional standards, and he correctness of the calculation may be confirmed by measuring an actual chainring with an even number of teeth. I did both and checked with a 1982 Japanese Industrial Standards manual. You may find my calculations in the Microsoft Excel workbook here. And here is the page from the JIS manual. | ||
* [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)] | |||
==Wie man Lochkreismaße berechnet== | ==Wie man Lochkreismaße berechnet== |