First off, best of luck training for RAGBRAI. It’s a blast of a ride.

Just throwing this out there but an easy way to get “cheap” miles if it works for you is commuting by bike to work.
It may not seem like much, but over the course of the year, they do add up. My commute is 9 miles one way. I try to ride a couple of times a week to work. On the days I drive, I take my clothes in for the next time I ride in. I live in Wisconsin, so to be conserviative, let’s say I ride only 26 weeks out of the year, thats about 900 miles I’ve added to my base.

See you on the ride, and have fun!
Cyduke.