Bikes aren't always a viable replacement - my parents travel with large (up to 100 pounds) instruments. Also, bikes are frequently a poor idea in inclement weather, making them non-ideal for things like transit to work if you've got a reasonable distance to travel. If I ride my bike to work, it's 15 miles - I won't bother in the rain. It'd be slower than any of my public transit options, and considerably less safe.
You'd be surprised how much weight you can transport on a bike with appropriate gearing and a trailer. I'm not sure what your public transit options are, but unless I've got a straight-shot light-rail route to where I'm going or it's really hilly, biking is almost always faster than public transit for me.
