Unfortunately, buying a new road or triathlon bike isn't all that trivial. Somehow, new bikes never seem to fit quite as comfortably as that first one ever did. Our bodies are now fully grown, less flexible and maybe a little more finicky than they used to be. Just like bicycles themselves, our bodies come in all shapes and sizes and little nagging pains can rear their ugly heads even during the shortest of rides.
There are, fortunately, very common areas of discomfort that can often be addressed and adjusted swiftly by a good bike fit.
And remember: If you buy a new or used bike, take the extra time to schedule a personal comprehensive bike fit. It can make all the difference between logging hours of adventures on your new bike versus letting it collect dust in the garage.