I have to dissagree with you. If you wish to show motion and speed in your picture it would be better a panning shot rather than cropping the horse's tail. Maybe in another kind of picture the crop will work, but this is not the case IMO. When I look at this picture I do not feel motion, the only I see is a sharp picture of a frozen horse floating on the air. Just my opinion, maybe in a more professional forum you will get a different opinion...
I just want to say that all of you who say cropping off the tail made the picture less then what it could have been, well you need to read and study more about photography. by cutting off the tail as i did, it show MOTION and SPEED which is what the challenge called for, but am i mad no this is what i expect from dp challenge, thats why i left and went to a forum that is way more professional.
this is some serious sports photography. what a moment captured in camera. if the tail was completely in the frame and there was a bit room on the top of rider's head...it would have been perfect. so i am giving you only 9 :)