A bicycles wheelbase is a rather simple measurement to make. Comparing wheelbases of different models of bicycles will help establish what types of activities the bike will perform best. Also, riders may find a wheelbase they find most comfortable for their type of riding.
Lay the bicycle on its side. You may also want to ask someone to hold the other end of the tape measure while taking the measurement.
Measure from the hub, or centre, of one wheel to the hub of the other. The hubs are in the centre of the wheel and are directly above the point on the wheel where it is in contact with the road. This measurement is the wheelbase of the bicycle.
Set the bicycle up to ride again.
Compare the wheelbase of various bicycles to find one that fits your riding style. According to Sheldon Brown's Bicycle Glossary, bicycles with shorter wheelbases are more manoeuvrable than longer wheelbase bikes. Conversely, longer wheelbase bicycles are more stable and easier to maintain in a straight line of travel.
Wheel size is often used to specify the size of a bicycle. The wheelbase of bikes with the same size wheels can vary. Measure the wheelbase to determine the likely handling characteristics of the bike.