I will be mountain biking in mountain lion country. What concealable handgun & load is best for protection?

Gun must be concealable beneath a tee shirt on a hip holster, or fit in a small fanny pack (3 - 3.5" barrel). Would .45 ACP, .45 GAP, .40 S&W, or .357 SIG be adequate for up close and personal confrontation out of a short-barreled Glock, Kahr or Colt clone? Suggestions please.