6 Rules Of Bike Fit by Andy Pruitt

RULE 1: BIKE FIT IS A MARRIAGE BETWEEN BIKE AND RIDER.
If you and your bike are incompatible, the marriage will fail.  Just as married couples must adjust to each other, so must a bike and rider.  However, a bike can be adjusted in multiple ways….But the body can be adjusted in only minor ways.

RULE 2: MAKE THE BIKE FIT YOUR BODY, DON’T MAKE YOUR BODY FIT THE BIKE.
It’s easy to adjust the bike but difficult to stretch or contort your body into some preconceived ‘ideal’ position.  Therefore, it’s important to focus on making the bike fit you, rather than your trying to match the way another cyclist rides….So forget what your favorite pro riders bike look like unless your body and your riding style are carbon copies of his.  Make your bike look like you, not like your hero.

RULE 3: DYNAMIC BIKE FIT IS BETTER THAN STATIC BIKE FIT.
Most bike fit systems are static, that is, adjustments are made with a rider sitting motionless on a trainer or from a set of formulas using body part measurements (Lemond Method).  There is nothing wrong with these static methods of bike fit.  Static and numerical formulas are an important starting point from which we move to dynamic fit. 

When your pedaling, you are constantly moving on the bike.  As you pedal, you actually rise or levitate slightly from the saddle.  Therefore, the adjustments made when your sitting motionless will result in a different saddle height than if measurements are taken while you are pedaling.  Reach to the handlebars can change as well. 

RULE 4: CYCLING IS A SPORT OF REPETITION
Cycling by nature is an endurance sport, demands continual repetition of the same pedaling motion for the duration of the ride.  Each pedal stroke is almost identical.  Your knee tracks in the same plane when observed from the front, and it bends the same amount at the top of each stroke.  As a result, a minor misfit can lead to major problems over time. 

RULE 5: REMEMBER THE FIT WINDOW.
There is a window of good fit for each rider.  Most standardized bike fit systems will get you within 2cm of this fictional ‘perfect’ fit.  But over time your body will lead you to make adjustments that bring you within this ‘fit window’ of a centimeter on either side of your virtual ‘perfect’ measurement.  If you are presently comfortable on your bike, that’s great.  If not, keep working at finding a better position.

RULE 6: MOUNTAIN BIKES ARE THE EXCEPTION
These rules apply to road bike riders as well as people who ride mountain bikes on the road.  When riding on the road, your position stays the relatively the same, and you spend a low percentage of the time out of the saddle. 

However, riding a mountain bike on technical terrain…lessens the repetition somewhat.  Because of this, fit on a mountain bike is a bit different from fit on a bike ridden on the road.  For instance, many mountain bikers like their saddles 1cm lower than they set on their road bikes.