A Chat With Andy Pruitt

Don’t miss out on the latest CyclingTips updates.

Jump To Comments

A couple weeks ago we had the opportunity to sit down for a chat with Dr. Andy Pruitt and Scott Holz who were visiting Australia from the US. Both are arguably two of the most renowned and respected authorities on bike-fit. We spoke to Andy Pruitt and Scott Holz about their experiences with positioning the pros and their philosophies with bike-fitting.

Besides being one of the first people to bring bike-fitting into practice, Dr. Pruitt has an interesting background. He was wounded when he was 14 in a hunting accident and his leg was amputated below the knee. Despite this, he was a successful amateur able-body racer (Cat 2 in USA). He won two National Championships and two World Championships as a disabled rider. He ended his competitive career in Seoul with a sixth place at the 1988 Paralympics. He still goes pretty well for an old guy and manages to pin on a number a few times a year.

Pioneering Bike-Fit

“Bike-fitting came to me when I was the head of sports medicine at the university in Colorado at the time during the Coors Classic in the late 70’s. At the time there was very little scientific based medicine in cycling. Pro Cyclists would hear about this guy [me] who worked on the football players at the university, but he was a cyclist himself. They would end up coming through my back door with their injuries and I would go through the detective work, which often related back to bike-fit. I would look into pedaling mechanics, orthotics, changing positions on the bike to make their pains go away.”

This is where medically based bike-fit began and Pruitt was one of the first (along with a few others sprinkled around the USA) to begin practicing this. Bike-fitting theory goes back slightly further than Andy Pruitt however. The Italians wrote the first book on bike-fitting (often referred to as the “Italian Cycling Bible” published by CONI, the Italian Olympic Committee, in 1972). They spoke about hamstring flexibility, saddle comfort…all the things relevant to proper bike-fitting things but had no solutions for them. They just spoke about them, but then moved on to old concepts like having the front hub in line-of-sight with the bars.

From here, Andy Pruitt helped develop Specialized’s Body Geometry Fit system. He currently works as an independent consultant to Specialized in addition to running his own practice out of the Boulder Center for Sports Medicine with his 60 employees. He says that cycling would consume 100% of his time if he let it, however he likes the variety of working with soccer, baseball, football and other athletes. Keeping his cyclist clients to about 30-40% of his workload is what he enjoys.

Fitting versus Sizing

To put “bike-fitting” and “sizing” into context, we should define exactly what they mean. Sizing should be a basic customer service. This includes the salesperson making sure the customer is on the right sized bike, has right handlebar position, and the saddle position is fairly close. It’s a 15min process. Sometimes people will test a bike at the shop and perhaps love it or hate it. Quite often however it was the position of the bike was test-ridden, not the bike itself. Proper sizing should be done by the sales person at no cost and is a basic and essential service.

Bike-fitting is a 2.5hr process that comes at a price. It entails and initial physical assessment, going through the fitting process itself, document the position, showing the client what’s going on with it, follow up after the position has settled and refining the position. I had a BG bike fit done a couple years ago and you can read about my experience with the process here. In my view, the $300 that a bike fit costs is an effective way to get either the low hanging fruit or marginal gains which will help you be more comfortable and to ride longer and stronger.

Recent advancements of bike-fit

Dr. Pruitt explains that bike-fitting has come a long way in the past few years. “Traditionally bike-fit was Italian or Belgian based. It looked at the X-Y plane [the side view]. It was all about saddle position and handlebar drop and position. The Italians assumed you were in your 20’s, male, and Italian. The Belgian-based bike-fit based itself on segment lengths (e.g. in-seam measurements). Neither formula had anything to do with flexibility, strength or asymmetries. None of them addressed the Z-plane [the front view] nor did they have an initial assessment on flexibility and injury. Even today the Body Geometry fit is the only one that dives into the Z-plane alignment: hip-knee-foot alignment, shoulder-elbow-hand alignment, pelvis being square on the saddle. My job is to get those legs working like perfect pistons pushing on those pedals. ”

Saddles shape and choice are other huge improvements that have been made in bike-fitting. “We’ve done a lot of development on saddle shape and choice and how it affects the z-plane. Ischial tuberosity support [sit-bones] is crucial to knee alignment and foot placement. Often people are riding a saddle that’s too narrow for their sit-bones.”

Scott Holz explains that the new saddle designs are a huge leap forward in bike-fit methodology. “It used to be that they’d teach that the only place you can make a true bio-mechanical change in somebody’s position was at the feet. Now we know this is not true and the saddle affects the biomechanics of the lower extremity movement hugely and is key.”

Changes in materials have been a big part in refining bike-fit. Saddle shells have come a long way with plastics, different strength nylons, and different carbon lay-ups to build flex at certain points. EVA foams can also be used to manufacture saddles with different densities at different places have become available in recent years.

Handlebar shape has also been improved. Ergonomic thinking combined with materials that are no longer confided to a round shape have made comfort on the bike much better than ever before.

Bike-Fit Philosophies

There are a couple different approaches to bike-fit. Some specialists believe that bodies are asymmetrical, so the bike should be adapted to the body. Others believe that the body should be able to adapt to a proper fitting bike. Andy Pruitt’s philosophy is a slight mix of both. “We want the bike to look like the rider, without impacting on the quality of their ride. I’m not going to move the saddle off-center or anything like that. The bike needs to be balanced with good handling characteristics; you need to be able to ride with no hands. The only way to do that is by making the bike fit you. The bike includes the shoes, gloves, and the saddle. We want to support those imbalances and asymmetries, not exaggerate them. But we don’t want to support symptoms, without understanding and addressing the root cause.”

Apart from spending the time and money on a bike fit, there are a lot of things that cyclists can do for themselves to be more comfortable on the bike and reduce the risk of injury. Core strength, glute strength, flexibility are key areas that people often neglect. Roman Kreuziger is a good example who Pruitt worked on. “Roman had a significant problems. His right glute was dropping off to one side and we couldn’t change his saddle because of the team’s sponsorship commitments. We prescribed some glute strengthening exercises and 6 weeks later he got significantly better.”

Hamstring length and hip flexion are also crucial to getting more power out of your pedal stroke and injury prevention. Someone with tight hamstrings will need a lower saddle height which will lead to knee pain after long-term use.

Do you ever see a professional rider and think. “Gee I’d love to work on his position” ?

“YEAH ! Absolutely, sometimes even after I fit them! Sometimes we are limited by sponsored equipment choice, and I can’t make all the changes I would like to.”

“Take Jens Voigt for example, he looks ugly on his bike today, but he was even uglier 5yrs ago! We made significant changes to him. Here’s a good example of changes we needed to make because of sponsorship conflicts. The team was sent the new pro titanium pedal from his sponsor, which was made lighter by making the pedal axel shorter. Jens needed a wide stance because of his big bowed legs, but the pedals he was sent from his sponsors jammed him into a narrow position. We found that the sponsor actually had a less expensive product which had a longer pedal axel which significantly improved Jens’ position.”

“Tom Boonen was another rider we made big changes to. I met him in 2008, when Specialized was the bike frame sponsor to Quicksep. He came to us with knee pain. We fixed that by putting shims in his shoes. His position at the time was really ugly. But he explained that his position was set up to what he thought was the most advantageous for the sprint in the last 3 kilometers, having no regard for the first 200 kilometers. We convinced him to try a new, more neutral, more comfortable position for the first 200 kilometers, for the long haul to make him fresher for the end, and that seems to have worked for him! We also made a saddle change, a shoe change, a stem change, and change to narrower handlebars. He used to ride 46cm bars. There was no reason – that’s just what he always used and thought wider might be better. Tom was excellent to work with. He was very open minded.”

“One of the interesting things about bike-fitting, and the growth of bike-fitting as a product is that it has trickled up to the Pro ranks from the average rider, rather than down from them.”

Watch – interview with Andy Pruitt on Cycling Central

Editors' Picks