Unsurprising, racing saddles are very small and lightweight. It is generally accepted that ‘dead’ weight, in the form of the saddle and any lead weights added to it, is more laborious for a horse to carry during a race than the ‘live’ weight of the jockey alone.
Indeed, rather than sitting upright in the saddle, modern jockeys rarely, if ever, sit in the saddle at all. Instead, they crouch in the stirrups and hover, relatively stationary, above the saddle in what has become known as the ‘Martini glass’ position. Consequently, a racing saddle has a relatively long, flat seat, with no dip, and really only exists to accommodate the extreme forward flaps and very short stirrups which allow jockeys to adopt their characteristic modern riding posture. All racing saddles have just a single girth strap. Racing saddles designed for National Hunt racing typically have larger flaps than those designed for Flat racing, to provide a more secure lower leg for jockeys over hurdles and fences.
Regardless of the ‘code’ of racing, the purpose of the racing saddle is to make the jockey more mobile and to bring him/her into closer contact with the horse. In terms of weight, racing saddles typically weigh in somewhere between a miniscule 4oz and a rather more substantial 5lb, with 1lb or so being about average.