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Andy Pruitt on Bike Fit

by John Hughes

John Hughes is former director of the UMCA. He has been certified by the NSCA as a personal trainer and by USA Cycling as a coach. See

Dr. Andy Pruitt founded the Boulder Center for Sports Medicine. He is a road cyclist, mountain biker and cross-country skier. His professional appointments have included: The University of Colorado, US Olympic Training Center, Tour de Trump/Tour DuPont, Bolder Boulder and the chief medical officer of USA Cycling for the 1996 Olympic Games in Atlanta.


Dr. Pruitt examines many professional and amateur cyclists. I have gone with a dozen different clients for bike fits with Dr. Pruitt.

Patient Exam

Pruitt begins each session by interviewing and examing the athlete:

Let's try that!
Pruitt setting up UMCA member
Wayne Greenway

Pruitt then does a physical exam, checking each knee joint for range of motion, testing flexibility, the integrity of the ligaments and listening for noise under the knee cap. He asks the rider to stand, looking for any hint that the legs are different lengths. He has the rider walk and examines how the feet land. If the feet roll in as the heel strikes, that will cause rider to walk and ride knock-kneed, stressing the knee joint.

Based on the rider's history and the physical exam, he then orders one or several X-rays. For knee pain, a frontal picture of the knees is standard. Pruitt says this is like putting a car on an alignment machine. The knee cap should be perfectly aligned, equi-distant from each part of the joint. One rider had hyper-mobile knee caps. The patella is designed to move up and down; his also moved left and right causing pain. Pruitt also uses this view to check the alignment of the joint surfaces and the integrity of the cartilage that cushions the joint during motion. He can also examine the underside of the patella for roughness. This roughness or chrondomalacia is common in all but the youngest cyclists.

If Pruitt suspects a leg length discrepancy, he also asks for an x-ray of the pelvis as the rider is standing. If one leg is shorter than the other, the pelvis will be tilted down on that side and, from the x-ray, Pruitt can measure the discrepancy. One rider, who'd suffered from serious back pain for years when cycling, had a 1 cm discrepancy. When Pruitt corrected for this, the pain disappeared.

Weight Lifting

Based on the interview, the exam, and the x-rays Pruitt will make some recommendations. For weight lifting, he recommends long lunges. This keeps the knee of the forward foot behind the toe and reduces strain on the knee. Squats (unless the rider has back problems) are also an excellent exercise for cyclists. Leg extensions are a no-no - the tremendous force that they put on the patella can exacerbate knee problems.

Knee Problems

For riders with knee problems, he suggests not running or hiking downhill, kneeling, or squatting for extended periods. Since the cartilage in my left knee is almost all gone, he said I shouldn't even stand much.

For riders with chrondomalacia, he recommends ramping up the training slowly and consistently. Chrondomalacia doesn't like sporadic training or big jumps in volume.

One rider was suffering from "spring knee", a common cycling problem. He'd been lifting a lot of weights and building up his mileage. Ramping up both the weightlifting and the cycling had caused an overload and strain of the extensor muscles.

Pruitt said that some aspiring ultra riders appear to have a glass ceiling, a training volume at which knee or other problems emerge and constrain the riding. The way to sneak through the glass ceiling is to build up very slowly and consistently.

Bike Fit

Dr. Pruitt mounts the bike on a trainer and has the rider spin against a light resistance. He begins by observing the rider from the rear and then from the side. One rider had only a 5 mm difference in leg length; yet, from the rear his left hip dropped noticeably as his shorter leg reached the bottom of the stroke.

Saddle Position

Pruitt starts by checking and adjusting the rider's position over the cranks, working back and forth among different adjustments:

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After each of these adjustments, Pruitt then re-checks the other aspects. Did he adjust the cleats so much because of knee pain that the change might lead to back pain? If he slid the seat forward or back, then he'll readjust the saddle height for the desired knee angle. For distance riders, he also suggests that after setting the saddle in a neutral road position, we may want to slide ii forward just a little so that we sit on the wider part. .

Stem and Handlebars

Now we're dialed in over the power train and can ride pain-free for days, right? No - often upper body pain is the real problem, and Pruitt is equally meticulous in checking the position of the torso, shoulders and arms. He starts with a question: when standing, can you easily bend over and touch your toes? If not, you have a stiff lower back and/or tight hamstrings and he'll compensate as he sets your upper body position.

Because we spend so much time on our bikes, proper bike fit is very important for ultra riders. In every tour a few riders sag and in every race a few riders drop because of injuries due to an improper marriage between rider and bike.

Boulder Center for Sports Medicine
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