Outside sponsors want big-time media exposure. Only a handful of mountain bikers in the world have this kind of impact. If you're an exceptional sport rider, you should try negotiating a deal with a local bike shop. Some bike shops may even offer a contingency fee for doing well in races. Contrary to popular belief, expert racers are not receiving cash, unless it's from their parents.
Most elites receive a free bike, perhaps some travel reimbursement and maybe a contingency program.
Once again, we're not basketball players. It's simple, follow these 4 steps. 1 - Submit a proposal now. People are negotiating contracts as you read this. 2 - Be specific about what you want.