Partner Spotlight : KGS Bikes - Why Do Bike Fits Vary From Shop to Shop?

Why Do Bike Fits Vary From Shop to Shop?

Kevin Saunders.
President, KGS Bikes

The hottest topic in bicycle retail is bike fit. Every shop recognizes the need to properly size a bicycle to the customer, or get the customer to adapt to the bike. It seems that almost every shop now has an expert "fitter" and they advertise perfection to all their clients.

Bicycle fitting is one of the most misunderstood concepts in the industry. Since most of it relies on the experience and style of the fitter, or a set of equations defined by a fitting system, the results can vary drastically from shop to shop and from bike brand to bike brand.

Another reason that bike fits are so varied across the country is, bicycle fitting is not easy! It takes a very good knowledge of anatomy, kinesiology, physics, geometry and the ability to relate in 3D a person trying their best to adapt to a bike that they want to a manufactured product with many dimensional limitations.

The "Holy Grail" of bicycle retail is to get a fitting system that will work for all customers with equal accuracy as well as be usable by all employees. The major systems out in the universe as far as volume include the Serotta Fit system, Specialized fit system, WobbleNaught, Fit Kit, KGS Bikes and others. Various devices are used to capture the data or the motion or to measure people so calculations can be made and the "perfect" bike is chosen. Dartfish, RETUL, a plumb line and measuring tape, cross hair lasers, video, setup bikes, etc. are all tools to help the fitter do the best job possible.


Besides the difficulty of a even an experienced and proficient fitter to do a great job on a bike fit, there are different schools of thought regarding the fitting of a bicycle. WobbleNaught, for instance, applies an equation on a specific bicycle and your physical measurements to allow one to adapt as well as possible to any bike. If the bike is the wrong size, no matter. The system will produce a set of dimensions that should be attainable on almost any bike to some degree. The equation is based on a young professional bike racer profile.

Serotta's fit system uses Knee Over Pedal Spindle to establish fore-aft positioning. KGS Bikes uses a balance point to achieve the optimum position, but due to differences in philosophy and end result, those positions will be totally different for the most part. RETUL is a motion capture device (not a fit system) that allows one to accurately determine angles such as knee angle, hip angle, etc. The capture device is incredibly accurate but is dependent on the external bony landmarks that sometimes do and sometimes do not correspond with the actual joint fulcrum point. This can cause variability.

Other reasons for variability are the bike shop's inventory combined with a customer's desire to get a bike when an emotional connection is made in the bike shop. People want "their" bike to fit because they want that bike. Sometimes they don't really care how well it fits as long as the coolness factor is good enough. Also, the bike shop wants to help the customer adapt to a bike so they can make a sale and provide instant gratification for the customer.

There are also untold numbers of bikes that are entry level and less sophisticated fitting techniques are used, like standing over the bike to see if the top tube clears your crotch. My personal favorite system is what I tell people with a wry grin, "The perfect bike fit for most bike shops in the world is the one where the credit card clears!"

Because of the variability of expertise and philosophies in bike fitting, I offer one thought. If you "take ownership" of your bike position and make the bike fit you rather than the other way around, you then get to really enjoy the sport of bicycling. Don't be afraid to listen to your body, either. You shouldn't have saddle problems, sore back, neck, shoulders or numb hands. You should be able to take your hands off the handlebars on a road bike and not feel like you are diving forward.

This is easier said than done. I believe that most people who say they are ok with their bike position have never experienced a truly comfortable bike position. The analogy would be similar to a first grader who couldn't see the board because she needed glasses, but didn't know the rest of her classmates could see, so didn't think there was a problem!

Remember this when you think about the relationship between you, your bike, and your bike shop. Once you spend your money, you have to ride the bike. You can educate yourself for free and be an informed consumer and you may be amazed at how much better your cycling experience can be.



KGS Bikes is known as the world's premiere bicycle fitting studio and boutique. For over 25 years, Kevin Saunders, President, has studied bicycle fitting and sold high end bicycles. KGS Bikes sells bicycles from Co-Motion Parlee, Serotta, Zinn, and Guru, in addition to fitting services. For more information visit the KGS Bikes blog, and the KGS Bikes website.