There are many good bike shops in Tucson. But you have to pay a visit to Ajo Bikes. They have a definite home-grown everyman atmosphere, and it's run by Frank Cook, one of the very nicest people ever to enter the bike business. You'll see an eclectic collection of all the usual bike shop stuff, plus recumbents, trikes, E bikes, etc. And if you call ahead, you're certain to be able to rent something appropriate for whatever riding you plan to do. I moved away from Tucson in '98 and it's been a few years since I've visited, but I always make it a point to stop in at Ajo Bikes and breathe in the ambiance.

If at all possible, ride Mt. Lemmon. Drive over and park at the base. Spectacularly beautiful 20+ ascent, passing through a bunch of different ecosystems, good roads, etc. Nice descent. I'm a scardy cat descender, so I ride my brakes, but I have friends who bomb the whole way down. Riding up to Kitts Observatory is also nice. Shorter ride but steeper.

Obviously, TriSports is a possibility (I think they rent); and, regardless, you should visit their store while in Tucson. Fairwheel Bikes definitely rents, and is centrally located right near the U of A campus. And, yes, a ride up Lemmon is a must (Gates Pass and the Reagan Loop are a close second). Enjoy!

Miles Ahead Cyclery on East Tanque Verde Rd - awesome shop. Geoff Gould is the owner and they have a group ride 3 mornings a week. If you are FAST, and I mean real fast then you could do the Saturday am Shootout. Lots of pros and cat 1's show up for it. But lots of crashes

Here are some upcoming rides in Tucson hosted by the local (and very friendly) bike club:

http://www.meetup.com/bikegaba/

if you want a safe rolling ride i always enjoyed the area out east, parking near saguaro nat. monument east and riding up spanish trail rd and colossal cave rd. through the town of vail and along the frontage road heading east on the north side of I-10 or crossing I-10 and heading west to eventually go to Madera Canyon.