Why could only teenagers work as ‘foreytors’?

Unlike the coachman, who sat on the coach box, the foreytor rose astride one of the front horses, usually in a line-pair harness – with the horses lined up in single file or pairs, one behind the other. His primary role was to control the front horses. From his seat on the box, it was difficult for the coachman to reach them with the reins or whip, so the foreytor served as a kind of "extension" of the coachman's hands, guiding the entire team in the right direction. 

The earliest documented references to foreytors in Russia date back to the early 18th century, although the profession itself likely emerged earlier, along with the widespread practice of riding in a tandem. By the 19th century, the foreytor position had become firmly established.

Most foreytors were serfs who worked on the estate. On wealthy estates, they often wore a uniform. The position required considerable composure and skill: they had to hold firmly in the foreytor’s saddle (which was lighter than a regular saddle).

This occupation had an important age restriction: foreytors were almost always teenagers or even very young boys, light and agile. The reason for this choice was purely practical: the horses were already pulling a heavy carriage and the weight of an adult rider would have been too burdensome for them.

In the seventh chapter of ‘Eugene Onegin’, Alexander Pushkin describes the Larin family's preparations for their journey to Moscow:

The cooks are preparing breakfast,

The carriages are being loaded to the brim,

The women and coachmen are arguing.

On a skinny, shaggy nag,

Sits a bearded foreytor.

To today's reader, the phrase "bearded foreytor" means nothing, but, to Pushkin's contemporaries, it would have been comical. This means that the family remained in the village for so long that, over the years, the foreytor grew from a young man into a bearded adult.

The history of foreytors came to an end at the beginning of the 20th century, along with the end of the era of horse-drawn transport. Nowadays, the knowledge and skills of a foreytor are, perhaps, possessed only by a very small group of specialists involved in horse breeding.