Matt Gilman was already a bike trials rider before he lost his eyesight in 2004 but he basically had to re-learn everything from scratch. I think the text at the beginning of this video says it all:
I hope this motivates someone who has a disability, to do something which they once loved. Even with a disability you are capable of doing something that was thought to be impossible.
Watching the video you would have no idea Matt is blind. Amazing.
