Originally Posted by Joshie
Well, you can always have a buddy fix the stirrup length while you're in the saddle. And, yes, thankfully our legs are nice and straight. When you get in the saddle one way to check length is to stand in the stirrups. It should lift you only a bit above the saddle.
Also, when your sitting in the saddle with your back straight and shoulders back, glance down to your foot without moving your head you should be able to see your toe lined up with your knee. That's how you know your leg is in the right position but be sure just the ball of your foot is in the stirrup and not the whole foot.