Some examples from the history of the development of the habits.

In the last few centuries the habits have changed considerably. More so in the last 50 years, but the habit began to change in the middle ages. Different trends changed designs but in the 14th century one could say "fashionable habits" emerged.
There was no riding dress especially designed for women in those days. They protected their garments from being splashed with mud and dirt by donning a cloak and pulling over their skirts a garment which could be called a "safequard" weather skirt, or riding petticoat, which was made out of some stout material, usually a heavy linen.

Hunter and his Lady (Beginning of the 14th century)
Hunter and his lady (Beginning of the 14th century)

During the time of the English-French wars the French Knights lost not only battles but their hold on the world of fashion. France handed over much of the art of fashion to a young, rich country called Burgund. The industry and trade were growing and the art was in rivalry with Italy. . Here was the birthplace of the modern art - in addition to Italy. There was fine line-fabrics, industry of silk and velvet factory and especially gold brocade.

Hunter in Burgund, 15th century (second part)
Hunter in Burgund, 15th century (second part)

Something of great importance to the development of riding happened in the 16th century; Catharine de Medici changed the riding seat. No longer did the feet rest on a sort of platform stirrup or foot-board, but now the right leg was hung over the upper or fixed horn of the saddle. This new style of seat lead the way to knee-long velvet or suede pants being worn under the riding or "flutter" skirt.

During the 17th century ladies rode solely for the purpose of showing off their beautiful dresses. By the 18th century riding had became a source of amusement and sport, leading the way to the development of "ladies only riding clothes".

The ladies of this time (1830's) wore a riding costume with sloping shoulders and  a long waistline. Long breeches were worn under the skirt which strapped under the riding boots. The neckline was a stand collar with a stock tied in a bow.

Habit 1795
Habit (1795)

Later in the 19th century women wore a corset, over which was a snug, white blouse and a jacket with small tails and fashion sleeves. The skirt changed very little and it was only in the 20th century that small changes occured - sometimes with the addition of a train at the back of the skirt.

women in a riding dress (1831)
women in a riding dress (1831)

After 1850 to the beginning of the 20th century the women wore a riding skirt which hung on the left side to the length of the spur. On the right side it was much longer and when dismounted the skirt was buttoned high on the waistline to even-up the length. Under the skirt the women wore long trousers with a strap or knee-trousers with a gaiter. The blouse took on more of a masculine style with collar and cravat. A cylinder and veil completed the costume.

The riding dress for women created the beginning of the riding costume.

The following pictures show different parts of a habit - in 1888.
Three kinds of riding-habits were made by fashionable tailors. Those for wearing in Central Park being different from those intended for the hunt, and the latter entirely distinct from the simpler habits worn in the summer in the country. English styles are closely copied in all kinds of habits, the skirt being made short and scant, the bodice extremely plain, and the trousers long enough to strap under the feet, or else short knee-breeches used with top-boots.

Parts of the riding habit
Skirt of riding-habit
Inner view of basque of riding-habit
Riding gloves
Collar pins for riding-habits

Riding boots (1888)
Riding boots (1888)

The following description and the picture are from a fashion magazine in the year 1898 .
Riding dress made from grey wool fabrics: The skirt had a leather lining. The tail of the jacket was divided into two "panels" which were fastened underneath with pique or fabric covered buttons.

Riding habit from Vienna (1898)
Riding dress made from grey wool fabrics (autumn 1898)

There was also a trend for the German Empresses (not Austrian) to wear the uniform and equipment of a high-ranking military officer, sometimes even that of the General. They rode only in side-saddle. The skirt had the same colours as the trousers of the General, but without the piping. Only the Hussar had silver stripes on both sides of his parade saddle cloth and unlike the high-ranking officers of the normal regiments he wore an old Prussian hat instead of a helmet. No guns were allowed, only sticks, and 21 elegant ladies in side-saddle formed part of the military regiment.

Uniform - Hoheit Herzogin Viktoria Luise von Braunschweig  und Lüneburg
Uniform - Hoheit Herzogin Viktoria Luise von Braunschweig  und Lüneburg
Prinzessin von Preußen (1912)

At the beginning of the 20th century the women wore a long skirt but later this gave way to a long, wide-dividing trousers. In 1909 in London, the safety habit was created - the back, front or side of the skirt was buttoned not a sewn seam. Now began the revolution of the riding trousers for women.

Habit -1921
Habit (1921)

This was a short story about the development of habits.