Maybe I'm wrong, but shin bang is from too much strain on the front of your shins. Racers get it all the time because they ski with a ton of forward boot pressure. When you land backseat off a jump, rail, etc, you get dead head toe and pain in the back of your calves. The best way to get rid of either of these is stretching, ice and massage. Point your toes to the ground and rotate your ankle...you should feel a light burn on the front of your shin. Other than that, try loosening the top buckle and strap on your boots one notch.