Biomechanics & Positioning

Body Geometry

12“Make the bike fit the body, don’t make the body fit the bike. It is not what the bike looks like leaning against the garage wall, it is how it functions under the rider!” Andy Pruitt, Positioning guru


More biomechanical research, please

Another off-season task is to test and tweak bike position. As you either re-establish your body for biomechanical functionality into next season or set up new equipment, now is a great time for a proper fit. Whether last season brought twinges or injury or the off-season aided postural corrections and rebalancing, it’s important to be mindful that dynamic physical developments require periodic bike adjustment. A new fit is best manipulated and adapted in this low intensity phase.


There are several methods for proper fit, such as taking 13measurements like the distance from saddle height to cranks, noting weight distribution fore to aft, and side-view leg angles. The best bike fitters assess a rider off the bike first, analyzing both static and dynamic posture, functional strength, and kinetic chain alignment. Next the fit moves to the bike with both static and in-motion analysis and measurements, also noting anterior view pedal stroke and aerodynamics.


It’s a privilege to have an experienced fitter’s eye evaluate you on a ride determining if variable terrain, cadence and effort affect the union of bike and body. Twice I’ve had major position changes with corresponding rehab: once from crash impact and another from improper frame size. Seeking expert advice saved me in the short-term.


Frequent fine-tuning of bike position was driven in the long-term by an acute kinesthetic awareness of changes caused by fitness gains, or muscular rebalance or better flexibility. 14This sensitivity and its ongoing adjustment “in the field” are keys for biomechanical longevity. One trip for fit is only a prologue for a bike’s seamless match with the body.


Prayer for Biomechanics

“I will make justice the measuring line and righteousness the plumb line.” 15Isaiah 28:17


We are thankful for the burgeoning research in cycling-specific biomechanics, bike geometry, and orthopedics. We recognize we sometimes must reprogram neuromuscular pathways for better bike posture. We ask for kinesthetic awareness. Bless position specialists, bring funding to cycling-specific biomechanical research.


Ponder When was my last fit and has anything changed since? Affirm I can move my bike for better biomechanics. Watch how position changes affect oxygen uptake in the short and long-term.


12“Body Geometry: Bicycle Fitting Seminar,” presented at USA Cycling Summit in Colorado Springs, Colorado, October, 2006 by Andrew Pruitt, Ed.D. founder of Boulder Center for Sports Medicine. Andy is remarkable not only for the expansive scope of his influence and expertise on positioning, but for his personal experiences in winning the disabled rider World Championships.

13Many schools of thought propose one particular standard. It’s best to take all these measurements and others as well. For instance, an old school method of heels on pedals – checks saddle height for many reasons. Newer procedures include more detailed analysis of body in motion multi-dimensionally, but there needs to be more field studies specific to elite cycling.

14Field adjustments mean regularly evaluating one’s own physical metamorphosis as a season progresses, seeking regular expert advice and appraisal, and readjusting for a host of variable considerations. It’s a science that becomes an art form.

15The Bible, New International Version, Copyright © 1973, 1978, 1984 by International Bible Society

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