A road bike, on the other hand, can use narrow tires built for speed because there is no danger of these tires sinking into the hard surface of the road. To get a clearer picture, assume that Figure A is a cross-section view of a horseshoe. Note how the ground surface is as wide, or nearly so, as the foot surface. Figure B, on the other hand, represents a low-flotation shoe, or one less able to support weight. Of the two, the shoe represented in Figure B would be better for general use, but the one shown in Figure A would better serve a show horse.
Flotation is similar to support, but there is a big difference.
If you were to fit a shoe fully on one quarter, you would be adding support to that quarter. If one branch of the shoe had a wider web, you would be adding flotation to that branch and preventing it from settling as far into soft ground. A bar shoe will add flotation while an egg bar shoe will add flotation as well as support. Adding flotation to the whole shoe keeps the whole shoe closer to the surface, while adding flotation to a part of the shoe keeps that part of the shoe closer to the ground surface. By using this principle, we can improve the way a horse moves.