Thanks for the input guys. I stopped at a cycle shop today and had it filled with nitrogen for $18. I originally bounced the type of gas idea around with a few guys I work with. I was just curious why N2 is always used in shocks.
I've recently rebuilt my Showa rear shock. The shock is bled. I need to re-charge the bladder. Question - Is it absolutely necessary to use 100% nitrogen? I have a bottle of tri-gas in my mig (Argon, Nitrogen, Helium). I was wondering why nitrogen? Could you use another inert gas? Why not atmospheric air?