Bike Fit 101

As a consumer it is important that you understand what a professional bike fitting should include so that you know what you should receive in your fitting and can make a good decision as to where you are fit. This has become more important recently since the term “Bike Fit” is now so commonplace in the cycling and triathlon industries that its meaning has become quite diffuse. Depending on the shop and the fitter, a “Professional Bike Fitting” can range from a 10 minute session that includes little more than being looked at while sitting on a bike or dropping a plumb bob from your knee, to a several hour session which actually aims to address all your needs.

The goal of a professional bike fitting is to allow you to optimize your cycling position, allowing you to be comfortable, powerful, stable, balanced, and efficient. However, blending these elements into an optimal position requires an understanding of your specific goals, biomechanics, and athletic history. This is why a good fitting must begin with a thorough interview. The fitter must know what the desired outcome for the fitting is before beginning work on the bike set-up. For example, if your goal is to ride comfortably and accommodate a back injury, a set-up designed to optimize aerodynamics in a 40k time trial performance won’t be beneficial to you.

Once you’ve had a thorough discussion of your needs with the fitter, your biomechanical limiters such as flexibility and core stability need to be assessed. Knowing what these limiters are will help paint a more complete picture for your fitter, since a fitting must work around what your body brings to the table, not some “statistically normal” body found in a formula based on averages.

Only after gathering all this information should your fitting move on to actually working on the position itself. Whether you are being fit for a new bike on an adjustable sizing bike, or having an existing bike fitted to you, the process is the same. Your fitter needs to work through the set-up in a logical progression, and address all contact points with the bike including the shoe/cleat/pedal interface, saddle height and setback, drop and reach to bars, and all the details of those contact points such as tilt of saddle and bars, and lever position. While making these adjustments, your fitter needs to be taking, and recording, key goniometric measurements such as leg extension and hip flexion manually or with the assistance of a motion capture system. Your fitter also should be explaining why your bike is being set-up as it is, helping you to understand the biomechanical and mechanical reasons behind each adjustment.

Once your position has been set, your fitter should thoroughly document the position, both in terms of where your body is as well as the mechanical set-up of the bike. The documentation should include enough information to allow your position to be moved from bike to bike over time and allow a new bike to be selected or designed for you now or in the future. Finally, you and your fitter need to have a conversation about everything that was done in the fitting, and answer any questions you have. Unless you have a thorough understanding of the fitting you just had done, the fitting is not complete.

Once you’ve gone through this process, there is one last step: riding. The goal of a proper fitting is to insure that you have good cycling experiences in the real world, and know that your position works for you. The biggest myth about bike fits is that you will “get used” to a new position. While you will adapt to a new position over time, becoming more efficient in it as you spend more time riding in that position, the fundamentals should work well right away. Whether you are new to cycling or have been riding or racing for decades, taking that first ride after a professional fitting is an eye opening experience for most riders as their bodies are finally in a position that allows them to reach their performance and comfort potential on a bike.

Additional Resources and Information on this Subject:
Difference Between a Bicycle Fitting & Bicycle Sizing
An Overview of Fit Tools Used by one MBFA Dealer