I think that is just no fair and no fun *pouts* When I asked for helmet advise on this forum some time ago. I was told that this helmet was not appropriate for horseback riding. I wanted one so badly just so we would look really fast going down the trail.A bike or skate helmet is NOT going to protect you properly on a horse.
Helmets are rated for the sport in which they are used, and equine helmets are the only type of helmets that should be used for horseback riding. Make sure the helmet you get is ASTM approved with a harness (in which to snap around your neck to attach the helmet to your head not one that just sits up there).
I believe Troxel makes a fairly cheap helmet and it's worth it.