The Crazy Bet: Clinical Bike Fitting

If I hadn't gone to see bike-fit guru Andy Pruitt, PhD, this past January, I'm not sure how much longer I could have continued cycling. Pruitt, founder of the Boulder Center for Sports Medicine, literally wrote the book on bike fitting. He’s also an accomplished racer—a two-time world champion in disabled cycling (he’s a below-the-knee amputee on his right side) who achieved elite Category 2 status against able-bodied cyclists. I’ve crossed paths with him at a few cycling-industry events over the years, and he’s suggested some minor position tweaks. But it wasn’t until he got me to his lab in Boulder, Colorado, that we realized what a biomechanical disaster I really am.

Since about the age of 30 (I’m 37), I’ve had a dull pain in my left knee that has grown more pronounced each year. Increasingly, it has forced me to cut my bike rides short. I’ve also had lower-back pain, though I’ve generally been able to ride through that. I attributed all of this to injury buildup—I suffered a partial tear of the MCL in my left knee once, and I’ve also broken both ankles and a wrist and had arthroscopic surgery on a shoulder.

But Pruitt discovered that my knee pain was largely due to the fact that my right leg is a full centimeter shorter than my left. X-rays we took at his lab showed my hips tilting down drastically to the right, with my spine twisting to compensate. (The image at right shows me standing up straight.) Pruitt also found that my toes point further out than normal and that I have a more pronounced varus tilt than average (hang your legs off the edge of a table and note how the outside of your foot drops down lower than the inside; that’s varus tilt).

Basically, my feet were too flat on the pedals and pointing too close to straight forward, which forced my knees to roll in and twist laterally. And by settling on a saddle height that felt most comfortable (or, rather, least painful), I was actually sitting too low for my left leg and too high for my right. My left knee was suffering from a lifetime of being over-torqued.

“The knee is usually the victim,” Pruitt told me. “The hips and ankles are the culprits.” Then he changed cycling for me. He put shims inside my shoe and under my cleats, to compensate for my varus tilt, and turned the cleats so that my toes pointed out as much as possible. This would keep my feet in their natural position throughout the pedal stroke, thus reducing knee strain.

Pruitt then moved my left cleat all the way back, which meant that my foot would be farther forward on the pedal, effectively shortening my leg, since it would now have to extend farther at the bottom of the pedal stroke. He also added three millimeters’ worth of risers under the cleat on my right shoe, effectively lengthening that leg. Combined with the cleat shift on my left shoe, this would roughly equal my legs out. Finally, Pruitt shortened my stem, giving me a more upright (less racer-like) position, which cyclists eventually have to move into in middle age. (Sigh.) All of this took about 10 minutes. (Download bradley-email012108-1.doc )

A big part of getting a medical bike fit is video analysis. Pruitt and BCSM biomechanics technician Sean Madsen set my bike up on a stationary trainer surrounded by an array of video cameras. Madsen attached infrared markers to specific points on my body (hips, knees, ankles, heels, etc.), which the motion-analysis software would use to track my movement in three dimensions. Videos shot before and after my position changes showed immediate improvement. (Download john_bradley.pdf) I looked more comfortable on the bike, and the motion analysis showed my knees tracking in a much straighter line. I didn’t suddenly have the pedaling grace of 2008 Tour de France winner Alberto Contador, but at least I looked at home in the saddle. “The goal is to make the bike fit the rider,” Pruitt said. “Not the other way around.”

The real test, of course, would come on the road. I’m happy to report that there was no break-in period with the new position—it worked immediately. I’m up to about 12 hours a week on the bike, and I haven’t experienced a single moment of knee pain in the four months since my fit session. I’m also putting out more power at lower heart rates for longer periods.

By Pruitt’s own admission, I’m a rare case. He said probably worst five percent. For most people, a fit session from trained bike-shop staff will be enough. But if that doesn’t have you feeling more comfortable, a full clinical bike fit just might save the sport for you. It did for me. Cost for a full medical fit at BCSM is $450 to $550. Full price list here.

—John Bradley

P.S. This weekend’s training rides will happen in Austin, Texas, where I’ll be attending the grand opening of Lance Armstrong’s new bike shop, Mellow Johnny's. Check back next week for a full report.

Sign up to win a $6,000 road-bike frameset here.

Comments

[John Bradley]

Hi, Mike,

Sorry. Forgot to include that very important information. Prices are $450 to $550. Here's the full price list: www.bch.org/sportsmedicine/ss-pricing.aspx.

—John

[Mike]

How much does a full medical fit cost?