Maggie's mum you are not too big to ride. Here's a helpful formula I ran into the other day concerning riders weight and horse's ability to carry--this is based on combined weight of horse, rider and tack. You can get a pretty good idea of the horse's weight using a weight tape. Your basic 15 hand horse is probably around 1000 lbs. You add up the 3 weights and divide by the measurement (in inches, sorry all you metric guys, its how its done here!) of the horse's front cannon bone half way between the knee and the pastern. You divide that result by two. Ideally the number will be close to 70, and under 80. More than 80, you need a lighter rider, lighter tack, bigger horse or horse with bigger bone. Both my horses are around 1000lb, i'm 190, my saddle is a lightweight synthetic, so we're dividing 1225 or so by 8 inches of lovely bone and yay, final number is 76 ish. Could be better but I'm not killing them. Now, having said that, my sis in law, who is probably 230 in her socks rode one of my horses for several hours, in a heavier but still fairly light synthetic saddle. The horse in question is pushing 20 years old, barefoot and carried her easily, was a tiny bit tender footed over some gravel but she's not used to it. She also has history of cracked hoofs and hoof abcesses so I'd be astonished if she wasnt careful of her footing. She not only coped, she outwalked my 13 years younger gaited mare, who was carrying me (a lighter rider) with a lighter saddle. Flat went off and left us in the dust. So dont worry too much, just be aware that depending on where your excess baggage is you might have some issues with balance or effective aids. it was interesting to me watching my sis ride, she hadnt ridden regularly for years, shes in her mid fifties (I'm still clinging to my early 50s!) and built like the Michelin man, I was scared to death every time the horse sped up or sis leaned or turned that she was going to get dumped but she stuck on just fine. You go, gilr!