Though I’ve never been to Juneau, I can point you in the direction of the Juneau Freewheelers bicycle club site. http://www.juneau.com/freewheel/
They’re the local group in Juneau, and they recommend Mountain Gears to rent bicycles from. http://www.geocities.com/~gears/
As for places to ride, I haven’t a clue, I’m afraid. The general word from people I know who have lived there is that there is NOTHING to do in Juneau, except to fish. Of course, that could be from the “trapped” feeling they also had while in Juneau, you can only get in and out by boat or aircraft.
There are several Alaska bicycling books out there, but I’ve never read them, and I don’t know if they’d cover Juneau. However, I can personally recommend The Milepost publication, which comes out every year, and logs every road in Alaska, with every restaurant, gas station, recreation, attractions, campgrounds and lodging (this is one thick publication!). It’s intended for motorists, and because you asked about road trips, I’ll tell you that the Milepost doesn’t give bicycle friendly ratings to each of the roads. But it will give you an idea of where everything is, and if you find a nice stretch of road near an attraction or park area you’d like to see, you can swing by the road in your car, check out the conditions, and see if you’d like to ride the road. In Juneau, you won’t have to drive far to do this. You can order a Milepost at their website, or pick one up when you get here, most grocery store magazine racks up here carry them. http://www.themilepost.com/
Please post how your trip to Juneau was after you get back! I would love to know in case I someday get transferred there; finding some nice places to ride makes any place feel more like home. And should anyone from Juneau read this, I’d appreciate your opinion on bicycle friendly roads and trails that you’d recommend as well.
Blondie