Originally Posted by
GrandpaEd
Just for the record, I will be 58 this month
Ratzelfrazzin'
kid.

I'm 62 and started racing last year, and there are several of us in the same boat over in the Master's Racing subforum. I'm not beating the kids, but I keep up with them on the fast team training rides which are usually 70-100 miles. I'm not a stud by any stretch of the imagination, I just work hard at it.
To add my voice to the chorus: you CAN build muscle. You CAN get faster. You've got the main ingredient already - desire. The fact that you've completed two centuries at a 15 mph average shows you've got the raw material, too. Don't let negative stereotypes of guys our age dissuade you from trying.
You already know that you can't get away with the dumb stuff we did when we were young. Chris Carmichael's
The Time-Crunched Cyclist, already mentioned above, is probably the simplest, most straightforward training plan available. I recommend you get it and read it through, then choose whichever plan of the four in the book you feel meets your needs and follow it.
Best of luck!