Being “sized” for a bike generally refers to using general “rule(s) of thumb” or formulas to choose a size in a given bike model. A bike “sizing” is the cycling equivalent of buying furniture before measuring your living room. Without proper planning, you will have to try to make the furniture to fit into the space and there will be compromises.  

      A bike sizing usually takes under half an hour and can consist of as little as seeing if the rider has stand over clearance over the top tube or (at the most) taking some basic body measurements and then selecting the bike size based upon this. A “sizing” is limited in scope and does not take into account important individual rider based variables or even whether the bike is even offered in a frame geometry that is suitable to your needs. The end result of a “sizing” is that the rider must do their best to adapt to the limitations and constraints of the model that is chosen. Despite these substantial limitations, the vast majority of bikes, even high-end bikes, are bought and sold by “sizing”.

      A "fitting" is an entirely different process. A "fitting" is the cycling equivalent to designing your new living room to first meet the needs of you and then selecting the furniture that you know will work. A “fitting” puts the needs of the athlete (you) first. It eliminates the guesswork as to what bikes and products are the best matches by building your riding position first and then using that information to help you consider only those bike models that will actually fit you well.

A bicycle fit done by a qualified professional is usually the most important step in the bike buying process as it eliminates the guesswork and guarantees that you will find a bike that is truly going to work well for you. That is truly an investment in your comfort and performance that will pay off not just during this bike purchase, but for as long as you ride and buy bikes. Shop carefully and ride smart.