Renting a bike in Chicago

I will be in Chicago in a few weeks to cheer on a friend for the marathon. As everyone is skipping out of town early Monday morning, and my flight doesn't leave until 4PM, I have some time to explore (yay me! :D) and would love to rent a bike to ride the Lake Shore Pathway. I'll be staying downtown close to the path (and the start of the marathon). Can anyone recommend a bike shop that can rent a bike? I'm not really fussy about what kind. I'll just be happy to be out there with those views! I LOVE Chicago.

On the north side of Millenium park there is a kiosk where you can rent bikes, segways, all sorts of stuff. Good rates, good bikes, have their own mechnics. They also do funky tours. http://www.bikechicago.com/

Oh, looks like a fabulous place! Thank you! I'll probably go to the one by Navy Pier - I can easily walk to that one, and ride from there. I'm very excited.

Yes, I forgot about the one at the Pier. My old roomie and I met up in Evanston and took the train into downtown to go biking. Our tour guide was awesome and crazy, but it wasn't a challenging ride. We did get all over though - all the way to US Cellular where the Sox play and all through China town and the lake front. The lake front was so amazing and beautiful.