English to Portuguese Tech/Engineering Automotive / Cars & Trucks wheels

A rotating mass, or rotor, is said to be out of balance when its center of mass (inertia axis) is out of alignment with the center of rotation (geometric axis). Unbalance causes a moment which gives the rotor a wobbling movement characteristic of vibration of rotating structures.


When talking about bicycle wheels, their weight typically receives a lot of attention. This is true for a couple of reasons: First, obviously weight of any sort in bicycle parts receives attention, especially for courses with significant uphill sections, and secondly, most people remember from their high school Physics classes that rotating mass also results in rotational inertia, or a resistance to "spin up". The common wisdom is that wheel mass, since it is rotating, counts "doubly bad" as compared to non-rotating mass. There's a grain of truth to this common wisdom, but it doesn't tell the entire story. In fact, in most cases, wheel mass and rotational inertia tend to be exceedingly small determinants of a particular wheel's performance; much less than the effects of the wheel's aerodynamics, or a particular tire's rolling resistance.