What Goes Into a Bike Fit?

 

Bike Fitting 101

By Lee Zohlman, USA Triathlon Level 3 Coach

Bike fitting is a vital part of cycling and triathlon and is probably as important as the actual type of bike we are riding.

Let me briefly give my background in fitting and then we’ll delve deep into some juicy fitting info. I first learned how to fit at the US Olympic Training Center in Colorado Springs and we dissected basic and advanced fitting for both road and triathlon cycling. They are very different to say the least.. After that I continued honing our fitting protocols with knowledge and input from Dr. Andy Pruitt from the Boulder Center for Sports Medicine and also with Paul Swift. In the past ten years I have been fortunate to fit many wonderful age groupers, Professional Ironman Champions and Olympians like Greg and Laura Bennett. Ok enough about that.

Bike fitting and from here on in we can assume to talk about tri fitting is a beautiful balance of comfort, power and aerodynamics. The human body accounts for up to 80% of the total drag when riding the bike so the position of the body is crucial to going faster. Just FYI the wheels are the next biggest place to save drag but I digress. The fitter has to look, analyze and critically observe many different components while fitting a rider and each rider is very different with different issues and goals.  Some of the components that have to be looked at are:

  • Type of race, a long course bike fit is different than a short course bike fit
  • Experience in the saddle, fitting a new rider also has different characteristics then fitting a veteran
  • Pre existing conditions or injury
  • Flexibility limitations
  • Type of bike being fitted. This is a big one. Fitting a road bike, a true tri bike or retro fitting a road to a tri bike is vastly different.

We do three main bike fits/analyses and have successfully used the CompuTrainer with our fits for many years. Some of our Basic Bike Fits don’t use the CompuTrainer at all and are highly successful in getting the rider more comfortable and aerodynamic at the same time.

The CompuTrainer allows us to look at the following:

  • Individual leg power output- crucial to see which leg is doing how much work
  • Heart rate
  • Cadence
  • Quantification of pedal stroke using the SpinScan feature- SpinScan™ Pedal Stroke Analyzer is an exclusive CompuTrainer feature that helps you increase power and efficiency. The multicolor torque graph represents one full 360 revolution divided into 15 segments. The left /right leg percentage power splits give you the feedback needed to pedal in “circles”. It will identify “flat” or “dead” spots in the pedal stoke where optimal power is not transferred to the drive train. A dynamic bike fit utilizing SpinScan is an excellent way to take the subjectivity and guesswork out of the bike fit process.

Absolutely we screen all our athletes before we fit them with a questionnaire and certain flexibility testing. But the fit starts at the foot. That’s where the power goes from your body into the pedals. We use a measuring device to see how much angle the riders foot has and how much we might need to shim their shoe to assist the rider into applying more power into the pedals.

After this measuring portion is done it is time to measure fore/aft positioning and saddle height. There are three main tools used here and they work in concert with each other. If the fitter is not using these tools then they cannot accurately measure these crucial areas. With the use of these technologies we can get the rider 5-15% more power on average but the most important thing is getting the rider more comfortable. Ideally, the triathlete will be able to hold their aero position for thirty minutes or more and actually be aerodynamic. This sounds a little odd but just being in your aerobars does not make you as aerodynamic as you could be.

Knee pain, low back pain, hand pain are all common for the avid cyclist who is not properly fitted. But, the biggest pain for triathletes is that sharp knife like pain between the shoulder blades. There is no need for this pain and there are many remedies for this.

In bike fitting each problem has a solution or number of solutions. Our aim with the fitting is to never judge the riders choices but to give as much information to the rider and then together we can make the best decision for them. I always say during the fit that the best thing about coming to an independent fitter is that we have nothing to sell you except a great fit. If we tell you that you need a new stem or handlebar it’s only because it will make you more comfortable and/or faster. The fitting should be completed with the rider riding at various intensities for a good amount of time to see what the body does under different loads. We all ride differently while warming up versus at a Sprint Triathlon pace. You all warm up don’t you? I know you do. Each one of the separate measurements actually reinforce each other so your leg extension on the bike should allow two distinct measurements to fall into place. Once all of these measurements are completed the bike fit is almost done. Rider feedback is imperative and about 20-30% of bike fits have to be seen a second time to be tweaked. This is normal and encouraged. Once this is done then the rider receives a sheet with their individual measurements and they are off.

How much time should be spent on your fit? Great question and a fit should never be judged on how much time is spent on it. I have spent thirty minutes successfully fitting a rider and also six hours. A great story- Ernesto Colnago, founder of Colnago Bikes, fit a dozen journalists precisely to new bikes in under an hour. We are passionate about bike fitting because it is so important and such a great way to get people to enjoy their bike more. We also love getting people faster and a good bike fit can and will do both. No one wants to ride when they are in pain and you don’t have to.

To schedule your bike fit with Coach Lee email him at leezee@bodyzen.com

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