I'm 39 and plannning on competing starting next year. However, because crit racing is so uber-competitive here I am focusing my training on triathlon. In tri, I can enter in age-group categories.

I have a cycling buddy who didn't start training until he was 40. Now in his mid-fifties, he recently completed a major tri in under 2:30, averaging nearly 22mph in the bike leg. As a comparison, my early-40s BF (a former collegiate track/cycling star who has been doing this most of his life) finished the same race in 2:40, averaging 19mph on the bike.

It's never too late to start!