A Perfect Fit: Why Bike Fit is Important for Every Triathlete

You have a fresh pair of sneakers, a brand-new wetsuit and a souped up bike; you’re ready for your next triathlon. Not so fast. You can buy gear to your heart’s content, but if it doesn’t fit right, an expensive purchase may end up doing more harm than good. In the same way you’d never run in shoes that were two sizes too big, you should also avoid training or racing on a bike that hasn’t been specially fit for you.

“In my experience, just about everybody can benefit from having their bike fit,” says Aaron Harrison, Fit Services Manager at Bike Gallery in Oregon. Indeed, the manufacturers design the bikes with certain averages in mind and very few people actually fit those averages. That’s precisely why they make so many of the components adjustable.

“Bike fit is crucial to maximize rider comfort, efficiency, and to prevent injury,” explains Harrison. Whether you’re jonesing for a new bike or devoted to an older pair of wheels, be sure to visit a bike fit specialist before you hit the road. Not only will you enjoy the ride more, you’ll also avoid injuries and increase performance.

Skirting Injuries

Knee pain often materializes after too many miles on a bike with poor seat position. Neck soreness results from handlebars or aero bars that are too low. Lower back ailments are usually caused by a seat that is too far away from the handlebars. The problems don’t stop there. “Bike fit works to both treat and prevent injuries,” says Todd Carver, co-founder of Retül, which offers a state-of-the-art bike fit system to fitters worldwide. “If your bike is fit properly, you likely won’t develop an injury in the first place.”

“Perhaps most important, a good bike fit can significantly improve lower leg alignment and knee tracking through the pedal stroke to minimize the chance of injuries to the knees and hips,” says Harrison. Just as it is important to practice running and swimming form and technique, you must practice this on the bike. If you aren’t initially positioned correctly, your mechanics will be limited.

Performance Enhancement

In addition to limiting your chance of encountering a sidelining injury, proper bike fit also improves performance. “Bike fit can have a big effect on aerodynamics and speed,” explains Carver. Harrison agrees, saying, “poor fit severely decreases performance, especially by limiting lung capacity or exceeding an athlete’s range of hamstring and hip flexibility.”

If you are forced to bend in the middle of the spine, the lung’s lower lobes aren’t able to effectively take in air and, in turn, produce power. This type of bend usually occurs if the position is too long or too low. A position that exceeds a triathlete’s range of motion at the hamstrings and hips also can impede performance. When the bike doesn’t fit comfortably and correctly, it oftentimes becomes difficult to maximize time spent in the aero position. Since this position is directly related to faster speeds and gives a break to the core and upper-body, the fit should accommodate it.

Bike Fitting Basics

A good bike fit considers many factors. The fitter should first become acquainted with the athlete’s goals, athletic experience and injury history. Bike fitters will check many of the following biomechanical factors:

1. Hamstring flexibility and range
2. Hip flexion
3. Internal and external rotation of the knee/hip
4. Shoulder width
5. Foot evaluation
6. Ischial  tuberosity (sit-bone) width
7. Core strength

After the initial physical assessment, the athlete gets on the bike so the fitter can determine where to make adjustments. While some fitters still use a tape measure and plumb bob, many have graduated to higher tech solutions. That’s where systems like Specialized Body Geometry Fit and Retül come in. Providing dynamic, 3-dimensional measurements and assessments, they have taken bike fitting to new levels. “Starting in 2000, dynamic fit really started to be the gold standard,” says Carver of Retül.

Using motion capture technology, they can determine everything from cleat and saddle placement to stem length, handlebar height and base-bar width, as well as aero bar adjustments. A bike fit using Retül technology includes these steps:

1. LED markers are placed on the wrist, elbow, shoulder, hip, knee ankle, heel and toe.
2. The rider begins to pedal, sending data related to the pedal strokes and movements of the rider.
3. Data is put into a final analysis so the fitter can make the necessary adjustments.
4. Using The Zin, Retül’s handheld digitizer, the fitter digitally measures the bike at 13-15 points and adjusts it to fit the rider.
5. Data is stored to keep a fit history on the rider for future reference.

Voila! You have a properly fitting bike. On average, you should head in for a check-up every three years. But with the new wave of fit technology, you might just find yourself going in more often. Who knew fitting a bike could actually be fun?

About the Author

Mackenzie L. Havey

Mackenzie L. Havey is an IRONMAN triathlete, marathoner and author of the forthcoming book, "Mindful Running" (Bloomsbury Publishing, October 2017). She writes about endurance sports, fitness and outdoor adventure for a variety of publications, including Runner’s World, Triathlete, SELF, TheAtlantic.com, OutsideOnline and espn.com. Learn more at MLHavey.com.