So here is the deal, I come to Vegas a few times a year and it's nice to rent a bike and enjoy the warmer Vegas weather in the traditional cold months. By that I mean November - March. Riding in the summers in Vegas is borderline insane.
I've used Southwest Bikes a few times now for rentals and have always had a good experience. First the online reservations is awesome. You can pick out sizes, styles, peddles ... basically you can see exactly what you're getting before you show up. The staff is super friendly and helpful. They answered any questions I had about the bikes and even gave some suggestions for routes in the area. The bikes are in tip top shape, even for rentals. My bikes have run smoothly and I didn't have to mess with any of the components. The prices are lower than other bikes shops in the area as well ... win/win
Although I typically bring my own stuff (shoes, helmet & gloves) they always offer to lend me some for the day at no charge. Bottom line, the staff is beyond helpful and makes the whole experience pain free.