Harness racing is a form of horse-racing in which the horses race in a specified gait. They usually pull two-wheeled carts called sulkies, although races to saddle (trot monté in French) are still occasionally conducted, especially in Europe.
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.
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.
Pacing races constitute 80% to 90% of the harness races conducted in North America. Pacing 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. The belief that hopples are used to create this gait is a misconception, the pace is a natural gait, the hopples are merely an accessory to support the pace at top speed.
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.
Most races are run on tracks constructed solely for harness racing (and may even have banked turns), but a few tracks conduct both harness and Thoroughbred flat racing.
Until the 1990s, harness tracks featured a rail on the inside, much like Thoroughbred tracks. This changed to the use of pylons, usually of a flexible material, which marked the inside boundary of the course. This innovation was mainly for safety reasons, as it allowed a driver to pull off to the inside of the course if necessary, avoiding injury to him/herself, their horse and other competitors. In addition, this change allowed another innovation called "open stretch racing," where an additional lane was opened to the inside of the traditional placement of the rail. Assuming the race leader was positioned on the rail at the top of the home stretch, that leader was required by rule to maintain that line (or perhaps move further out), while horses behind the leader could be moved into the open lane and potentially pass the leader. This helped alleviate a common problem where trailing horses would be "boxed in" behind the leader and another horse to the outside, and made race results more wide open — and thus more attractive to bettors with potentially higher payoffs. Open lane racing is only used in certain jurisdictions.
New Zealand racing is quite similar to that of Australia. Many horses are able to easily "cross the Tasman" and compete as well on either side of the sea that separates Australia and New Zealand.
In both New Zealand and Australia the same system of an 'open lane' operates, although in Australia it is called a 'sprint lane' and in New Zealand a 'passing lane'. These lanes do not operate on all tracks and have been a point of argument between many industry participants.
The most notable harness tracks in North America are the Meadowlands Racetrack in New Jersey, The Red Mile in Kentucky and Woodbine Racetrack and Mohawk Raceway, both in Ontario (harness racing is more popular than thoroughbred racing in Canada). 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 26 times.
The major events for open age pacers in Australia are the Miracle Mile, A.G. Hunter Cup, Victoria Cup and the Australian Pacing Championship. The most prestigious events for three year olds including the Victoria Derby, the New South Wales Derby and the Australian Derby. In New Zealand the major races include the Auckland Cup and the New Zealand Cup as well as the Noel J Taylor Memorial Mile and the New Zealand Messenger Championship. There are also the New Zealand Derby and the Great Northern Derby for three year olds.
For the younger horses there are series that stem from yearling sales including the Australian Pacing Gold and an Australasian Breeders Crown.