The Difference Between Bike Sizing and Bike Fitting

Coach and Bike Fitter Rick Schultz answers your questions about bike fitting basics. 


Bike sizing generally refers to the size of the frame and is done first and happens before you purchase your bicycle. While getting fitted the bike shop will take 2 measurements, which are then converted into a range of sizes based on current industry accepted formulas. With modern frame geometries and the various options in stem lengths, seat post lengths, crank arm lengths, etc., a cyclist can be sized to fit on up to 8 different frame sizes. For example, based on height alone, a cyclist who is 6’-0.5” (72.5”, 184cm) has an industry accepted frame size range of 55 through 62. Your local bike shop will start asking questions to help narrow down this range.


There are three ways bike shops look for your correct frame size.

HEIGHT – the least accurate since, for a given height, people can have long legs/short torso or short legs/long torso. This method has the most variability and results in a wide range of frame sizes for a given height. As stated above, using this method, up 8 frame size options exist.

INSEAM – a little more accurate and is based on your inseam measurement. Since you only have 1 inseam measurement, one frame size is shown using this method. For example, let’s assume that the same 72.5” cyclist has a 34” or 86cm inseam. This would convert to a 59cm frame. So now more questions need to be asked by the bike shop. Since one customer might want to race, another might want to ride 100 miles on Saturdays, this frame size based on inseam measurement is not a ‘one-size-fits-all’.

HYBRIDboth HEIGHT & INSEAM – in my opinion, the most accurate. With this method, a frame size can be narrowed down to 2-3. For example, the resulting table (using the same cyclist as mentioned above) would indicate a recommended frame size range of 58, 59, 60, but also, can accommodate special cases such as extremely long or short legs where frame sizes of 56, 57, 60, 61 are also acceptable.


Bike fitting is accomplished after the customer has bought their bike. Bike fitting is the result of bike sizing and is the practice of fitting the bike to the person. The three important components to a bike fit are; cleat fitting, saddle height/fore/aft positioning, and cockpit sizing – including stem length and bar width. For maximum enjoyment and fun, you need the correct size frame that is custom fit to you.

Check out Rick’s product reviews website,, and his coaching site, Rick is now working with Jax Bicycles as their premier bike fitter using the new state of the art Trek Fit System. Come on by and give it a try. Rick can be reached at [email protected] or at 949-606-2767 or contact him at Jax.