Your Fit Index is a number that represents the ratio of your torso length to your overall body height. Fit Index is not influenced by gender, making it a true indicator of fit.

Bodies with a higher Fit Index have a proportionally longer torso require less handlebar height (Stack) more saddle to handlebar length (Reach). Riders with a lower Fit Index, proportionally long legs, need just the opposite, more stack and less reach. 

 these riders are the same height, but different Fit Index

these riders are the same height, but different Fit Index

Fit Index Calculator

You can measure inches or centimeters, just use the same units for both measurements. True Inseam is typically an inch or 2 longer than your pants inseam. If you're unsure, check our measurement tips below.

True Inseam:

Your Fit Index:
 Fit Index (FI) =   50 - (100 x Inseam ÷ Height)

Fit Index (FI) =  50 - (100 x Inseam ÷ Height)


Fit Index is on a scale of 0-10

Height: measured barefoot

Inseam: measured from the floor all the way to the pubic bone. Feet should be bare and shoulder width apart.

Technique: Use a hard cover book or section of 2x4 or the like and place it between your legs. Pull up firmly on the book to push through the flesh to the pubic bone. This should be slightly uncomfortable, not painful. We want the full structural length of your leg. With the book held level and firmly in place mark the height on the wall, then measure. Having a helper take the measurement will increase its accuracy.

You'll most likely find that your ratio is between 0 and 6. A negative or greater index number are possible.

How do we apply the Fit Index?

Performance fits use a Fit Index to ensure accurate placement of the handlebars to maximize your efficiency. Alex, long torso, riders have an index between 3 and 6 and Drew, long legged, riders have an index from 0-3.  Learn more: Alex Fit, Drew Fit

Relaxed fit (Riley) bikes prioritize uprightness and comfort over ultimate efficiency. Riders with a fit index between 0-6 will be comfortable on this fit. Learn more: Riley Fit

Easy Fit bikes are designed to position you in a very upright position, so your leg length ratio has almost no effect on your reach.