Here's a look at three different cranks that Doug Herbert Performance has for different purposes. Engine builder Ron Viccaro says while lowering overall weight is preferable, it's usually not as critical as lowering the rotating inertia-or weight on the extreme ends as the crank rotates. But most important of all is making sure there is enough material left on the crank to keep it as stable as possible. Any flex in the crankshaft kills power. That's why the more standard-looking cranks in the background are raced more often than the more radical crank in the foreground. Viccaro says if there is no damage, a crank will usually last around 6,000 miles before being replaced.