Friday, February 25, 2011


I photographed the new bike chain a few days ago. It was worn and needed to be replaced. Unfortunately I rode the bike way too long with the worn chain, and as a result, the work chain damaged the set of gears, or sprokets on the rear wheel. The assembly of sprockets is called a cassette. The smallest gear has 11 teeth on it, and the largest has 26 teeth. This is what gives a racing bicycle the huge range of gearing for different conditions. When 10-speed bikes were first made, the sprockets were just flat circles with teeth, stamped out of steel. Now, as they add more gears and use narrower chains, these assemblies are just astounding works of complex machining. The teeth of the sprockets are not all the same, they are not symmetrical, and "shifting ramps" are machined out of the metal as well. But what a gorgeous piece of machinery this is!

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