I have a single-speed bike, a road bike, a triathlon bike, and a mountain bike. My daughter has 2 road bikes. My son has a road bike, a mountain bike, and a "going to school" bike. My wife has a road bike. And my dog has a bike.
My dog has a bike? You bet. It has a special attachment on it (spring loaded) so she can run beside the bicycle. It's pretty fun for her and her cyclist. Here's a photo of my beautiful wife biking with Lucy on their way to Colectivo for an afternoon cup of coffee.