Which sport would make use of a cart called a sulky?
The sulky was originally a lightweight, four-wheeled cart designed for one horse. Its single, open seat for one person was fixed on its shafts. The sulky evolved into a two-wheel design and was used extensively in the United States by doctors and others who made extensive trips by themselves. Today, the sulky is found almost exclusively used in harness racing. The modern version consists of a lightweight metal construction. The U-shaped shaft curves around the narrow seat where the driver sits.
Harness racing is a form of horse racing in which the horses race at a specific gait (a trot or a pace). They usually pull a two-wheeled cart called a sulky, although in Europe racing under saddle (trot monté in French) is also conducted.