Originally posted by toolfreak
First of all, if you had a big bang and everything is allright, get up the bike and ride!
The longer you wait, the more nervous you get and if you sit down, your body will be painful and stiff too.
If you aren't in a race and you crash I wouldn't spring back up on the bike too quickly. Even if you think you're alright, an adrenaline rush can mask the pain of an injury. Catch your breath, walk a few paces and make sure you're good to go.