Bike Fit Evaluation: Can It Help Diagnose And Prevent Cycling Injuries?
- Volume 19 - Issue 12 - December 2006
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The sport of cycling has seen tremendous growth in the past decade. Athletes are utilizing bicycling not only as their primary sport but also as a form of cross training and rehabilitation. As a result of this growth, there has been a corresponding increase in the incidence of non-traumatic (overuse) injuries. Wilber, et. al., found 85 percent of cyclists to be suffering with one or more overuse injuries with the following distribution: neck (48.8 percent), knee (41.7 percent), groin and buttocks (36.1 percent), hand (31.1 percent) and back (30.3 percent).1
While overuse injuries of the foot, ankle and leg are not as common, they can have an impact on the cyclist. Sports medicine podiatrists are commonly called upon to consult on cyclists’ lower extremity injuries, especially those injuries that have defied diagnosis and those that have not responded to initial conservative treatments.
Since overuse injuries in cycling can result from many causes and are often multifactorial, a thorough evaluation of the cyclist is paramount. Comprehensive evaluation of the cyclist includes a patient history, physical exam, an equipment check and cursory evaluation for proper bike fit. Video analysis can be helpful to evaluate cycling technique but it is usually not necessary in the initial evaluation. By systematically evaluating the cyclist, one can determine a definitive diagnosis and the exact cause(s) of the overuse injury.
The patient history can uncover training errors, identify environmental factors and reveal systemic disease. The physical exam localizes the problem and identifies biomechanical faults and muscle imbalances. An equipment check ensures that the bicycle and shoes are appropriate for the patient and in good working order. Evaluation for proper bike fit is often overlooked in the clinical evaluation process but one should consider it, especially in patient/cyclists who have persistent symptoms despite attempts at initial treatment that has been ineffective.
The goal of the sports medicine podiatrist is to ensure that the cyclist has a reasonably good fit to the bicycle as this will enhance comfort and decrease the potential for injury. If there is any concern about bike fit being an issue in the evaluation process, a professional who specializes in bike fitting can always perform a formal bike fit analysis at a later date. Bicycle fitting has become a highly specialized field with special measuring systems and equipment developed to aid in the process.
How To Assess Frame Size
There are several key factors to consider in doing a cursory bike fit evaluation. By considering each of these factors and making appropriate adjustments as necessary, one can help optimize patient comfort and efficiency on the bike.
Frame size. One should consider this factor, especially if it is obvious during the initial observation that the bike frame is either too large or too small. Two methods of determining proper frame size include crotch clearance and use of the inseam measurement to determine seat-tube height. Crotch clearance applies to most road bikes with a horizontal top tube. (This method will not work for bikes with angled top tubes.)
While patients straddle their bike in bare feet, there should be at least 3/8-inch to 1 inch of clearance between the top tube and the cyclist’s crotch. On most road bikes, one can measure frame size in terms of seat-tube height from the center of bottom bracket to the top of seat tube. This is called center-to-top or c-t sizing. To determine seat-tube height, measure the inseam height. Have the cyclist stand barefoot with his or her back against a wall and his or her feet 6 inches apart. Place a book between the legs and push it firmly up into the crotch area to simulate saddle pressure while riding.