Refining the Art of Bike Fitting

At Gear West Bike, we are constantly evaluating the quality and caliber of our many bicycle fit services. Our goal is to remain at the forefront of fitting by offering a valuable and straightforward approach; leaving you fully satisfied with your bike. To stay at this level, we have purchased an EXiT Fit Bike that can accurately emulate every bike frame geometry, allowing the rider an accurate comparison of several prospective bikes that they wish to purchase.

With a comprehensive stack and reach database, we can use this piece of equipment to mirror the measurements of our key brands (Felt, Trek, Quintana Roo & Cervelo) as well as any other brand on the market, to take the guess work out of your high end bicycle purchase. With this fit, you can be assured that you are ordering the bike that is best for you, maximizing your potential during that next road or multisport race. Here is a detailed overview of how the EXiT Fit Bike works.

Before we jump into how the EXiT Fit Bike works, we need to define a couple of key terms that are paramount to the fitting process today. The first term that needs to be defined is stack. Stack is how high a frame’s head tube top sits above the bottom bracket. Reach is how far the head tube top sits in front of the bottom bracket (diagram represented below from Slowtwitch).

Both measurements are important to know in a world of sloped top tubes, more or less aggressive bike geometries, and variable seat-tube angles.

Seat tube angle also plays into the purchase of a specific bike. A more vertical seat tube angle typically allows for a more comfortable riding position while in the aerobars and a more aerodynamic position. A more relaxed (less steep) seat tube angle is seen in traditional road bike geometry. This less steep angle allows for better climbing, sprinting, cornering and group riding. Refer to the image below to preview the difference in seat tube angles between a road and triathlon bike.

With a basic understanding of stack, reach, and seat tube angle, it is easier to understand a common fit scenario that exists today. Consider two bikes. One bike’s sizing is identified as 60cm and the other bike’s sizing is identified as a 62cm. When reading the traditional sizing chart (head tube height and top tube length) of the two bikes, the 62 cm bike initially seems to be both taller and longer than the 60cm bike. But if you look closely you will see that the 62cm bike is only taller, by 2cm, not longer. The top tube measures 1.2cm longer but the actual fit of the bike does not have the bike any longer. This is done by having a seat tube angle that is one half degree more relaxed; 72.5 degree on the 62cm versus 73 degree on the 60cm. The problem with ignoring the Stack and Reach measurements of any bike is this.

If we go by the assumption that any given rider has a preferred, if not ideal, saddle position, both vertical and for/aft, to the bottom bracket then that rider would want/need to be in that saddle position on any and every bike of that style which they ride. For instance suppose I have a saddle height of 76cm from Bottom Bracket to saddle top and the nose of my saddle on my tri bike is 1cm in front of the bottom bracket. This means that every tri bike I ride would have to the saddle adjusted to this position. If I were to switch bikes and the new bike had a shallower seat tube angle, I would then need to slide the seat more forward on the rails to accommodate the saddle position I prefer. This would be artificially changing the seat tube angle and simultaneously shortening the top tube length. However, the “reach” of the bike is not changed, at least how it is measured with stack and reach. Remember that the reach is the measurement across an imaginary plane from the center of the head tube to the center of the bottom bracket.

The EXiT fit bike allows us to make many fitting adjustments simultaneously in order to find the bike best suited for YOU. As you can see from the photos below, stack, reach, saddle height and positioning (fore and aft) can be adjusted easily to achieve the most comfortable and efficient position.

Additionally, different aero cockpits and crank lengths can be experienced during the time of the fit with simple adjustments on the EXiT cycle. Once we have achieved a position where you are most comfortable, the measurements from the EXiT bike (stack, reach, seat height and seat position) can be plugged into a geometry application to determine which bike models have the closest geometry to that experienced on the fit stand. Ultimately, this allows us to select the bike that is without a doubt, the best for you given your body type and comfort. Rest assured, when you make the decision to purchase a new bike using the EXiT Fit Bike procedure, you will know exactly what you are purchasing!

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