The Importance of a Proper Bike Fit

Cycling Weekly will tell you the best way to increase your cycling speed is to bend and tuck your elbows, ride with other triathletes, do intervals, pump up your tires, brake less, ride in the drops, lose weight, build muscle, buy an aero bike and wheels and buy tighter clothing!

While all of this is great strategy, let's take a look at the basic elements that will help the average triathlete ride faster...  While cycling on a flat road aerodynamic drag is by far the greatest barrier to speed - it accounts for 70 to 90% of the resistance felt while cycling depending on physiology.  Think of drag this way - the thicker the medium you're moving through the more drag your body creates. Given that air is thinner than water, your body position creates drag, but not as much as when you're swimming... The drag created by your body while riding your bike is directly related to your position on the bike while pedaling through wind... The only obstacle greater than wind resistance is the force needed to overcome gravity while pedaling uphill!

The primary reason for investing in good bike fit is to maximize your aerodynamic position (reducing drag) while concurrently maximizing your physiology's ability to absorb oxygen (dynamic energy production just below your anaerobic threshold.) Remember, the faster you go the more wind resistance (drag) you need to overcome...

According to Cyclingtips.com the top four things the average triathlete can do to improve speed performance are investment in an aerodynamic triathlon suit, the addition of aerobars or the purchase of a triathlon bike, procurement of an aero helmet and investing in a bike fit.  In fact, they've gone as far to calculate the cost per second saved, per the chart below:



The chart is based on a 40KMS ride at 48 minutes - faster than the average coyote!

The main points for any triathlete are:
  • Race in an aerodynamic uniform.
  • Buy the best triathlon bike you can afford. On a limited budget I'd advocate buying the bottom of the top! Buy the best used or new bike you can afford!
  • Use an aero helmet in every race!
  • Get a good bike fit!  Pro athletes race in a more aerodynamic position than may be comfortable for you, i.e. elbows tucked in, hips tight and close to the bottom bracket and knees close to the top tube. Get a bike fit before you buy a bike to ensure proper stack and reach:
    • Stack (the vertical distance in centimeters or inches from the center of the bottom bracket to the top middle point of the head tube, where the fork passes through the frame.) Good stack results in an angle from the hip to the knee to the ankle of 150°+/-).
    • Reach (the horizontal distance measured in centimeters or inches from the center of the bottom bracket to the center of the head tube/ stem.)

If stack and reach are correct for your physiology oxygen absorption will be maximized while drag is minimized! Remember, you can move towards a more aerodynamic position over time as your level of fitness increases.

For a custom bike fit or consultation, contact Ed at ezboyle@gmail.com.

Ed Boyle, the owner of Jachin Boaz Triathlon Training, is a F.I.S.T. Certified bike fitter using Retul dynamic bike fit technology with video motion capture analysis.