Every high-performance crankshaft has a specific bob weight value, such as 1,800 grams. A gram is a metric measurement equivalent to 11/428 ounce. An 1,800-gram bob weight is basically the amount of weight in each of the counterweights. However, you don't just add all the values up to determine bob weight. The formula is 100 percent of the rotating weight plus 50 percent of the reciprocating weight. Let's use an example to see how this breaks down:
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