Umm, just my 2 cents from another non lawyer:
Gimpy, if you're under 18 and only you signed that waiver (ie: not your parents) SunPeaks owes you a new bike and some ass kissing.
You're a minor and no contract/waiver you sign is legally binding, and they know it too - or their lawyer sure as hell does. You could have signed it in front of a judge, tv cameras and the prime minister, it's still worthless if you're under 18.
Hence most public sport places where you could get hurt - every paintball field I ever played on comes to mind, require your parents signature.
Get your parents to have a lawyer to send them a letter - unless they really want to be jerks about it you should get a new bike damn soon.