The Breed

In most jurisdictions harness races are restricted to standardbred horses. Cold-blooded horses are raced in Scandinavia, and European horses often have partly French or even Russian lineages. Standardbreds are so named because in the early years of the Standardbred stud book, only horses who could trot or pace a mile in a standard time, or whose progeny could do so, were entered into the book.

Standardbreds have proportionally 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.

The founding sire of today's standardbred horse was Messenger, a gray thoroughbred brought to America in 1788 and purchased by Henry Astor, brother of John Jacob Astor. From Messenger came a great-grandson, Hambletonian 10 (1849–1876), who gained a wide following for his racing prowess. However, it is his breed line for which he is most remembered. The lineage of virtually all American Standardbred race horses can be traced from Hambletonian 10's four sons.

Races

Races can be conducted in two differing gaits; trotting and pacing. The difference is that a trotter moves its legs forward in diagonal pairs, right front and left hind, then left front and right hind striking the ground simultaneously, whereas a pacer moves its legs laterally, right front and right hind together, then left front and left hind.

In continental Europe races are conducted exclusively between trotters, whereas in Australia, Canada, New Zealand, the United Kingdom, and the United States races are also held for pacers.

Most harness races start from behind a motorized starting 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. The other kind of start to race is a standing start, where there are tapes across the track behind which the horses either stand stationary or trot in circles in pairs in a specific pattern to hit the starting line as a front. This enables handicaps to be placed on horses according to class with several tapes, usually with 10 metres in between. Some European, Australian and New Zealand races start using tapes.

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. There are strict rules as to how and how much the whip may be used.

North America

Almost all North American races are at a distance of one mile (1,609m), and North American harness horses are all assigned a "mark" which is their fastest winning time at that distance. Harness races involve considerable strategy. Track size plays an important part here; on the smaller half-mile and five-eighths rings common to harness racing early speed becomes a more important factor, while the longer stretch runs of seven-eighths and mile tracks lend themselves more favorably to closing efforts. Usually several drivers will contend for the lead out of the gate. They then try to avoid getting boxed in as the horses form into two lines -- one on the rail and the other outside -- in the second quarter mile. 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 on small tracks 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.