Harness racing, a popular form of horse racing at local tracks nationwide, differs from thoroughbred racing by using standardbred horses that pull a jockey on a two wheeled cart called a sulky, rather than carrying the jockey on their back. Unlike thoroughbreds, these horses have shorter legs and do not sprint. Instead, they pace or trot, with races handicapped by requiring stronger, more mature horses to run longer distances than their younger counterparts. Because of the size of the sulky, traditional starting gates are not commonly used. Instead, many races begin with a rolling start, with a vehicle leading the field before pulling away as the race begins.