In most jurisdictions harness races are restricted to standardbred horses although cold-blooded horses are raced in Scandinavia. Standardbreds are so called because in the early years of the standardbred stud book only horses who could race a mile in a standard time were entered into the book.
Standardbreds have shorter legs than thoroughbreds and longer bodies. They also are of more placid dispositions, as suits horses whose races involve more strategy and more re-acceleration than do thoroughbred races.
Races are conducted in two gaits. In continental Europe all harness races are conducted between trotters. A trotter's forelegs move in tandem with the opposite hind legs -- when the right foreleg moves forward so does the left hind leg, and vice versa. In Australia, Canada, New Zealand, the United Kingdom, and the United States races are also held for pacers. Pacers' forelegs move in tandem with the hind legs on the same side.
Pacing races constitute 80% to 90% of the harness races conducted in North America. The horses are faster and, most important to the bettor, less likely to break stride (a horse which starts to gallop must be slowed down and taken to the outside until it regains stride). One of the reasons pacers are less likely to break stride is that they often wear hopples or hobbles, straps which connect the legs on each of the horse's sides.
Most harness races start from a motorized gate. The horses line up behind a hinged gate mounted on a motor vehicle which then takes them to the starting line. At the starting line the wings of the gate are folded up and the vehicle accelerates away from the horses. Some European races start without a gate.
The sulky (informally known as a bike) is a light two-wheeled cart equipped with bicycle wheels. The driver carries a long, light whip which is chiefly used to signal the horse by tapping and to make noise by striking the sulky shaft.
Almost all North American races are at a distance of one mile, and North American harness horses are all assigned a "mark" which is their fastest winning time at that distance. Harness races involve considerable strategy. First of all, drivers try to avoid getting boxed in as the horses form into two lines -- one on the rail and the other outside -- at the beginning of the race. They may decide to go to the front, to race on the front on the outside ("first over", a difficult position), or to race with cover on the outside. On the rail behind the leader is a choice spot, known as the pocket, and a horse in that position is said to have a garden trip. Third on the rail is an undesirable spot, known as the death hole. As the race nears the three-quarter mile mark, the drivers implement their tactics for advancing their positions – going to the lead early, circling the field, moving up an open rail, advancing behind a horse expected to tire, and so on. Unlike thoroughbreds, harness horses accelerate during the final quarter mile of a race. The finishes of harness races are often spectacular and perhaps more often extremely close. The judges (equivalent to thoroughbred stewards) often have to request prints of win, place, and show photos to determine the order of finish.
Notable harness horses include Dan Patch, a pacer who was the leading sports superstar in the United States in the early twentieth century; Greyhound, a trotter who is arguably the most dominant horse in any era of the sport; Bret Hanover, a pacer; Cardigan Bay, a New Zealand bred pacer who was the first harness horse to win $1 million in North America; Ourasi from France and Mack Lobell of the United States, both trotters, who dominated in the 1980s but who in their one confrontation competed so gamely on the lead that they tired at the end and were overtaken; Cam Fella, a pacer; and Matt's Scooter, a pacer.
The most important harness tracks in North America are the Meadowlands and Garden State Park, both in New Jersey, and Woodbine, in Toronto (harness racing is more popular than thoroughbred racing in Canada). Important Canadian races are the North America Cup (for pacers), the Canadian Pacing Derby, and the Maple Leaf Trot. Since 1947, the "United States Harness Writers" Association annually votes for the "Harness Horse of the Year." Since inception, a pacer has received the honor 31 times and a trotter 25 times. An oustanding accomplishment for harness horses that has only been accomplised by a few is the Triple Crown of Harness Racing for Pacers and for trotters who make up one in five standardbreds in racing it is the Triple Crown of Harness Racing for Trotters.
Since 2000, the $1 million Grand Slam Prize in harness racing has been offered to any harness racing pacer who can win the North America Cup (Woodbine Racetrack, Ont.), Meadowlands Pace (Meadowlands Racetrack, N.J.), Little Brown Jug (Delaware County Fair, Ohio) and their Breeders Crown event (Meadowlands Racetrack, NJ).
Similarly, a $1 million Grand Slam Prize is offered to the owners of a trotter that wins the Hambletonian (Meadowlands Racetrack, N.J.), the World Trotting Derby (DuQuoin State Fair, Ill.), the Kentucky Futurity (The Red Mile, Ky.) and their Breeders Crown event (Meadowlands Racetrack, NJ.
Some of the great harness pacing horses: (+ denotes a Triple Crown winner)