Bicycling (South Africa)

LOVE EVERY RIDE!

HOW 5 RIDERS DISCOVERED THE TRUE JOY OF CYCLING

- BY DR JEROEN SWART

THE PERFECT BIKE FIT!

I recently decided to get properly fitted to my bike. So I did a Google search to see where to go, and also asked a few friends. In the end, I was more confused by all the different offerings than I was before. How do I find out who to go to, and which system is the best? – Rael, Paarl

AI feel your pain, Rael. Until recently, bike fitting was an area based on lore and tradition rather than validated scientific principles. Luckily, science is catching up and there has been some particular­ly good research conducted by Wendy Holiday, a UCT researcher at our own Sports Science Institute of South Africa.

SADDLE UP

In terms of scientific evidence, the area that has been researched well is saddle height. Some systems use your inner seam measuremen­t to predict the correct saddle height. These are generally a poor choice, and scientific­ally proven to be wrong at least 73% of the time.

SHOOTING FROM THE HIP

Using trochanter­ic leg length is a more effective method. On the outside of the

leg, measure from the bony protrusion at the hip ( greater trochanter) to the base of the heel. This should always be done while you are sitting on the bike; the fitter will stop your pedal stroke at the bottom, to check the position of the knee.

Using the Holmes method (in which the pedal is placed in the horizontal position), your knee joint should have a range of flexion of 25 to 35 degrees. This has been shown to have the lowest risk of injury, and provide the highest power output and best economy (lowest oxygen consumptio­n).

CHANGE POSITIONS

The question of how far forward or back the saddle should be has not been investigat­ed as thoroughly. But Raymond Teo, also of the Sports Science Institute, conducted research into this topic recently.

Moving the saddle forwards will result in your quadriceps (front of your thighs) working harder; while moving the saddle backwards means you use your gluteals (buttocks) and hamstrings (back of your thighs) more. Which is best for you depends on many factors: the discipline, your experience, the distance being ridden, and others.

JOINT ADJUSTMENT­S

Once the saddle height and fore/aft position adjustment has been done, things start to get very sketchy. There has been little to no research on how to achieve the best hip, torso, shoulder and elbow position. We do know that extremes of hip position reduce economy (i.e. result in more oxygen consumptio­n). So an overly aggressive position (long distance to handlebar, and low handlebar) will cause problems – as will an overly conservati­ve position (sitting too upright).

Some bike brands (Specialize­d Body Geometry, Retul, ErgoFiT, and Shimano Bike Fitting) have developed their own commercial systems, having conducted in-house research that provides reference ranges for the joints mentioned. But these research findings have not been published, and you therefore have to go on faith or reputation that they are accurate and work well.

Other than using these systems, a fitter can also call on experience. This may sometimes look like voodoo, but there are some really good bike fitters out there who don’t rely on any specific system, but still achieve excellent outcomes.

There are also some very promising new technologi­es being used to optimise bike fitting. One of these is dynamic saddle-pressure mapping. Translated, this is the measuremen­t – while you pedal – of pressure in the various areas under your tush.

Seems like a strange way to do a bike fitting, but it works!

There has been little to no research on how to achieve the best hip, torso, shoulder and elbow position.

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