What Does SAG mean......

S.A.G. or sag means support and gear.  It is most refers to a vehicle that follows the riders, offering support and mechanical aid.  To SAG refers to riding in the vehicle instead of under your own power. (...on your bike). A 'sag wagon' is sometimes called a 'broom wagon' because it 'sweeps' the riders that lagging or need aid.

Karen Cooper, one of SAG drivers at a support stop with the SAG wagon.