jockey
Person who rides a racehorse; a jockey rides with very short stirrups and the body hunched over the horse’s neck.
saddle 
Slightly curved part that is usually made of leather; it is laid on the horse’s back for the jockey to sit on.
shadow roll 
Part that blocks the horse’s view of the ground; this prevents the horse from mistaking shadows for obstacles to jump over.
saddlecloth 
Padded piece of cloth underneath the saddle that protects the horse’s back from chafing and protects the saddle from the horse’s sweat.