Wow!!! I can't even begin to imagine receiving that phone call.
I'm a little late but if it helps...
You have two separate claims here.
The first is easy, property only.
Property means the following:
The bike
The gear your son was wearing
All of his clothes including underpants
eye glasses (if he wears them)
cell phone (if it was on his person it may have been damaged)
Sit down and make a list. Note the brand name if any of his clothing and research current list price. Same goes for his helmet and gloves and any other gear he was wearing.
As for the bike.
Again sit and make a list:
any mods
last service
tires
any thing to help establish the correct actual cash value.
The second claim is complicated. Bodily Injury claims are settled the moment you sign the bottom line and accept the check. DON"T DO IT!!!!!
Even if he feels all heeled up in 6 months DO NOT SETTLE!! If you have medical insurance and can afford to wait at least one year after healing do so. You want to know if he hurts when seasons change, when he runs, when he rough houses with the dog. It takes at least a year to heal.
In this case a lawyer sounds like a good idea. You need to get your time back also