I've been visiting family in Tucson my whole life but learned more than I ever knew about the city and surrounding area following our 2 hour bicycle tour with Jimmy! A few notes about my experience which I think capture its overall value:
1) Jimmy was born to be an unconventional storyteller (a guided bicycle tour of historic Tucson is one way of accomplishing as much). He's an savvy, jocular guide, keeping everyone engaged so that the two hour expedition never lulls or becomes redundant.
2) The route is well planned and provides a good snapshot of the oldest neighborhoods (charming stretches of adobe architecture) in Tucson, as well as its more contemporary and future-oriented areas (i.e. a jaunt through the university and along 4th Avenue, which is largely populated by teenagers). There is hardly any change in terrain, so you won't be huffing and puffing on your bicycle (which are very comfortable!).
3) This experience is really quite a good value --- $50 for 2 hours of entertainment, exercise and learning can't be beat. Be sure to tip well!
Can't recommend this more!