With drugs now, geldings are at no disadvantage. In fact, some trainers strongly believe they have an advantage in that you can better control their disposition and limit muscle growth (especially at the neck). I've read that geldings are usually taller because the epiphyseal plates close later. Longer legs would seem to be an advantage. For the cost conscience, geldings are nice because they usually require less feed. Controlling the disposition of the horse by the dosage of hormones when not training and more closer to the race can be helpful. Some of the more aggressive horses have to be gelded because of frustration or self-mutilation. My neighbor now gelds his good race horses after losing one a few years ago when it killed itself trying to get through a fence to get to his mares. As I understand it, the biggest disadvantage is that geldings often learn the bad habit of not picking-up their hind feet high enough when running.z