last shot would be mad from a different angle perhaps,
i just found the rider looked to distant with the tree cutting across the left of him, and the black and white just meant there was no colour to draw your attention to the rider.
my 2 cents on b&w riding shots, is that the rider needs to be very prominent, so when you take away colour, usually a bright t-shirt, of whatever, the rider still stands out.
anyways. just what i felt.
from a capturing the moment/riding, nice shots. above is just yr 12 art/photography mumbo jumbo, that sounds right to me. lol.
edit: love the first one!