Hey way to go the STP is a blast I did the last 3 this year I am doing the RSVP instead. The first year I did it I started the training rides about this time of the year. I tired to follow the recommended mileage they have on the Cascade site and I did very well the first time out. I only went on one training ride, bailed and trained with a freind on my own. This is a very achievable goal and is really easier than you may think. Just don't push yourself to hard and listen to your body Feel free to PM me with any questions you might have.

Here is a link to Cascades site. Good luck and have fun