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Professional bicycle fits: finding the perfect riding position on a bicycle

In my last article, I mentioned how important proper bicycle fit is to me, and how I compare the geometries of bikes with different frame geometry when I start looking for a decent ride. Of course, some of you may have asked how I got to the ‘proper bicycle fit’ part — this article outlines my experiences with a couple of professional bike fits and discusses the effects these fitting sessions had on my riding.

Introduction

Up until fairly recently, professional bicycle fits have been the domain of elite racers. These racers seek out the ‘gurus of bike fit’ who help them eke every bit of power out of their cycling and gain every aerodynamic advantage they can.

Most people give credit for bringing pro bike fits to the masses to Ben Serotta. Serotta’s fit classes have helped hundreds of fitters to become certified from locations all around the United States. This certification process has made quality fittings become more commonplace over the last few years, so much so that fits are now within the reach of amateur racers.

There are several different fit philosophies out there, and each approaches bike fit from a different angle. One thing that sets each of these philosophies apart is the way they deal with body measurements; some rely on a more traditional ‘body measurement’ fit while others emphasize ‘dynamic fittiing’. Dynamic fitting takes a rider’s flexibility into account when they are measured, and the rider is fitted while actually riding their bicycle (or a specialized fitting bicycle). More traditional fits (for custom-made bikes) use static body measurements, such as inseam, torso length, and arm length, that are plugged into formulae for frame sizing and stem lengths.

Regardless of the exact fitting philosophy, the goal among good fitters is the same: to provide riders with the most power efficient cycling position that works with their unique biomechanics, injury history, and cycling discipline.

Cost

There is no beating around the bush here. Professional bicycle fits are not cheap. Costs range from $25 for basic saddle positioning, to $150 for a more detailed fit, to $450 and up for 3+ hours of laser alignment, video analysis and the trained eye of the best in the business. Expensive? Yes. Worth it? That’s for you to determine for yourself.

Types of bike fits: using your existing bike fit or using a ‘fit cycle’

There are usually two ways to get a bike fit: using your existing bicycle; using a specially-designed, adjustable sizing cycle. Typically, each of these fitting bikes is connected to a trainer or even a computrainer that provides real pedaling feedback.

Using your existing bike for fitting. If you have a bike you like but want to tune your position on it, then getting fit on your existing bike is the way to go. Obviously, when using an existing bike, you can’t change the top tube length or angles of your current ride. Most fitters place an adjustable stem on your bike in place of your normal stem. They will also have a wide variety of saddles and handle bars at their disposal.

Keep in mind that, sometimes, people are just on the wrong bike to begin with. If a severely short or long stem is required to get the rider in the optimal position then it might be time for you to look for a new frame. The main reason for this is that stems outside of certain lengths will drastically change the dynamic handling characteristics of your bike.

Size cycle fits. A size cycle is a bicycle where almost all dimensions are adjustable and creates “points in space” that mimic a real bicycle. If you are thinking of getting a new bike — either a custom one or a stock bike — it would be worth your while to be fit on a size cycle, mostly because the final results provide you with dimensions that you can give to your custom builder or use as a template to find stock frames. Additionally, you can have the fitter set up the dimensions of a known bicycle prior to purchase in order to determine if the frame will work for you.

Road Bikes vs. mountain bikes

The majority of fits and fitters focus on road bicycles. On a road bike, riders are usually in a less dynamic position than on mountain bikes, and having a proper fit is an important part of achieving proper comfort. Additionally road riding generally doesn’t have the kind of terrain variations seen in mountain biking — this is one of the things that makes it a little easier to find a good fit on a road bike.

On a mountain bike, riders’ bodies are often in constant motion, especially when riding on technical terrain. Combine that with the incredible variations in terrain experienced by many mountain bikers — from ultra steep granny-gear climbs to big dropoffs — and you have the ingredients that help make a proper fit much more of a compromise, one that trades off between getting optimal power output and keeping the rider from going over the bars.

My experience with a professional bike fit

I’ve been riding bikes a long time and I’m always tinkering around and changing things and I ‘thought’ that I’d found a good riding position — until I saw a presentation on bike fitting. During my next session on the trainer, I noticed that my elbows were locked on my road bike (which is a sure sign of an improper fit), and this was on a custom road bike too. My local shop, East Coasters Bicycles recently started performing Serotta Bike Fits so I thought I’d give it a go.

I ended up getting a size cycle fit for a road bike and then transfering those dimensions over to my existing road bike, and then a few months later getting an existing bike fit done on my mountain bike.

Step 1: Interview and Injury History. The first step involves sitting down and talking with the fitter. My fitter and I went through an extensive question / answer with me about my cycling history and my goals. A significant amount of time was spent talking about past injuries as well as my current aches / pains. This step of the process took almost an hour.

Step 2: Static and Dynamic Measurements. In the Serotta system, the only static measurement taken is inseam. The purpose of this measurement is for determining proper standover height. It is not plugged into a pre-existing formula for determining saddle height or seat tube height.

One of the core philosophies of the dynamic fit revolves around the riders current degree of flexibility. While most xc racers strive for that pro-racer look (long, lean, bent way over, etc.), most of us are limited by our flexibility in how low we can get while riding. It was extremely eye opening to me how much my power output can be compromised when riders strive for positions that don’t fit your body’s biomechanical limitations.

The fitter measured my hamstring flexibility by lifting my leg up while I was laying on my back and then feeling when my hip flexors and hamstrings involuntarily tensed up. Also, he had me hold my shoulders and bend over as far as I could. These tests helped my realize that I have VERY poor hamstring flexibility. I mean bad.

During this stage, several other flexibility measurements were taken. My fitter also had me walk in socks back and forth to analyze my gait and pronation.

Step 3: Iterative fitting. The iterative fitting step of the fitting process zeroes in on your ideal in a constant, roundabout process. During my fit, one thing was changed, then another, and then repeated. EVERY single aspect of how I interacted with the bike was looked at:

• Saddle height
• Saddle fore / aft
• Cleat position fore / aft
• Cleat rotation
• Handlebar width
• Reach to the bars
• Brake lever position
• Leg length discrepancies, potential need for pedal shims
• Shoe size

Road bike fit results

One thing that was interesting is that my final fit was not what we expected. Since I’ve got long legs and a short torso, conventional wisdom suggested that I’d need a road bike with a short top tube. What we found out was that my poor hamstring flexibility required a very high bar to get optimum power output. While that wasn’t surprising, once proper bar height was achieved we found that I could tolerate a much longer top tube than originally thought.

Another thing my fitter did was to put me on a narrower bar. This IMMEDIATELY helped round out my shoulders — rotating my wrists slightly and eliminated an upper back kink that had been nagging me for years. Then he used a laser level to see if my knees were tracking in a vertical plane. It was found that one knee was great while the other was significantly offplane — a slight rotation of the cleat fixed this.

The Serotta philosophy likes the Knee over the Pedal (KOP). This is a subject for some debate for many people but it works for me very well. Another thing this approach prefers is to get the ball of the cyclist’s foot over the pedal spindle. However, I prefer the ball of the foot to be slightly in front of the pedal since it helps minimize my ‘hot foot’ and seems to provide me with more control on the pedal stroke. The fitter listened to my desires and adjusted his fit accordingly.

When we were finished with the fit, I felt super comfortable on the bike and the next thing on the ‘to do’ list was actually measuring my ideal riding position and determining what was required to get my existing bike to conform to it.

At home, I have an ergo trainer that measures power output. After the fit, I realized that I was able to do intervals at almost 10 watts higher than before the fit — a significant improvement that was a result of less stress being placed on my hamstrings.

Mountain bike fit results

The results of my mountain bike fit were more in line with conventional thinking. My shorter torso required a shorter stem and we also set the top of my bars level with the saddle (higher bars are common for downhillers and trail riders but xc racers tend to have lower bars). The short stem has had an awesome effect on my bike handling and I’ve also found it good for climbing really steep pitches, as it is easier to pull the bars back in synchronization with pedal strokes.

Again my poor flexibility meant that a higher bar was needed for me to achieve optimal power output. The downside of a higher bar is that it takes more body english to keep the front wheel down on steep climbs but I found myself adapting my climbing to the new position quickly.

Also, we went with a narrower bar, something that helped me get rid of that kink in my upper back (the same kink that my previous road bike positioning had created). It is amazing to all of a sudden be without that tight knot after rides.

Conclusions

There is a term known as “doctor dollaring” which, basically, means throwing money at something in order to fix it. Cyclists have created a culture of doctor dollaring by looking for any component or nutrition aid that has the potential to make their bike or their body faster.

However, I can say with confidence that getting a proper fit is one thing that is almost guaranteed to make you faster and more comfortable on your bike. As I stated earlier, I am an experienced cyclist and have been riding bikes for many, many years. Still, I was blown away by how much the bicycle fits that I did helped my riding.

Resources and further reading

• Serotta Fit
• Wobble Naught
• Boulder Center for Sports Medicine. Note: Andy Pruitt is considered to be one of the foremost experts on bicycle fit in the world.
• UC Davis Sports Medicine. Note: Dr. Max Testa and Dr. Eric Heiden are also known world wide for their fitting expertise..
• Cyclemetrics links to almost every bike fit philosophy out there.
• Pez Cycling Article on the Cyfac fit philosophy
• Pez article on Serotta Fit
• Slow twitch article on triathelete fitting

This entry was posted on Tuesday, February 7th, 2006 at 12:22 am and is filed under Tech tips, Features. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.