I rented a bike from Pro Cyclery on a recent visit to Las Vegas. The experience was first-rate from beginning to end. They took my reservation over the phone for a day rental of a road bike. They are able to provide virtually any type of pedal system as well as helmets and a saddle bag with a spare tire and tools, so the only thing you need to bring are your shoes. The bike was a brand new Giant Defy, full carbon fiber, with Shimano 105 group, fully set up when I walked into the shop. The bike worked flawlessly, and was a pleasure to ride. I rode a 41 mile route from their shop to and through Red Rock Canyon - absolutely beautiful ride. The ride to and from the Canyon was entirely on pothole-free roads with wide bike lanes, making it a pleasure. The staff / owners were extremely friendly and helpful, paying particular attention to my fit on the bike, making several adjustments before i headed out. I took a cab from my hotel to their shop, and they called a cab for me to get back to my hotel.
I have rented bikes from a number of shops around the country, and by far Pro Cyclery made the rental experience the most hassle-free of all of them. Highly recommended.