His average weight was around 1200 lbs.
Impost
impost
Impost.
Impost
He/she isn't, the horse is. The handicapper looks at the previous form (results) for all horses in the race and decides what weight each horse ought to carry to, in theory, make the race a dead-heat. The jockey and tack (saddle etc.) are weighed and anything below the handicap weight given to the individual horse is added as weights, into the weight cloth. Jockey and tack are weighed again after the race to check the weight, allowing a little for sweating of the jockey.
He had medical problems that he had been ignoring to make weight, and he passed out atop a horse in a race. He wasn't using his lucky saddle.
Conditions for a race typically set weights that are required for each horse to carry. These may be different for different horse based on their previous performances. When the weight (jockey plus equipment) weigh more than that assigned they are listed as "over weights" of "high weights".
Seabiscuits biggest rivals are War Admiral the son of the great Man O' War and Ligaroti to name a few.
If the odds of a horse winning a horse race are 2 to 7 then the odds against that horse winning the race are 7 to 2.
Yes, it WAS a race, it is no longer a horse race.
In horsespeak, Seabiscuit's grandsire on the top was Man-O-War, which translates to MOW was he grandpa on the father's side, or paternal grandparent.
The rider of a horse in a race is called a Jockey.