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Improving the Triathlon Position
By Tom Demerly

Fit and position are the most significant determining factors in bike performance. In these photos we show the results of two bike fits we did on triathletes who own bikes that fit them correctly, but had not been positioned optimally. The benefits of improving your position are multi-fold: You will be faster on the bike with less effort. You will be substantially more comfortable. You be more stable, able to eat and drink more easily while pedaling. You can see better and there is less muscular soreness and lower back distress. Saddle discomfort can be reduced. Most significantly from a biomechanical perspective, University studies conducted in England in 2000 suggest your run split will be much faster off a correctly positioned and fitted bike than a correctly fitted bike positioned poorly (Garside Study).

In This first example the athlete is too extended in the torso. The stem, originally a 120 mm, is far too long. this particular problem is compounded by the measurements of the frame to begin with, as this model of triathlon frame had slightly longer top tubes than is optimal per seat tube size. The athletes induced seat tube angle is far too shallow also, creating an uneven distribution of muscular effort resulting in fatigue for some muscle groups much faster than others. This results in a difficult and uncomfortable transition from bike to run.

Click to Enlarge

Click to Enlarge

In the improved version reach has been substantially reduced. This results in greater bike stability and a more powerful, compact position. Using the axiom "You can't fire a cannon from a canoe" the athlete could not generate powerful pedal forces in the "Before" position. In this more compact reach position significant power can be put into the drive train by "bracing" with the upper body. This is only for short burst of power up false flats and smaller climbs. The angle between the torso and femur bone are much more open resulting in easier breathing and better digestion, This is particularly critical in longer events. The proximity of the pelvis to the bottom bracket will improve pedal mechanics and result in more even distribution of pedal forces over the entire muscular package involved in pedaling. The position is biomechanically more efficient and powerful, safer, more comfortable and maybe even more aerodynamic. Note than the athlete's hands are positioned somewhat behind the shifters in this photo. Optimally, while cruising on the road, the hands would be extended forward onto the shifters giving the athlete fingertip control of shifting with no movement.

This position began too high and too stretched out. This is the type of position we most commonly hear complaints about back problems with. The lower back is to stretched and too high with the arms too far forward. the skeleton is not adequately supporting the upper body on the elbow pads- they are too far forward.

Click to Enlarge

Click to Enlarge

The re-worked position is more powerful, comfortable, stable and aerodynamic. The upper body is lower and the torso is supported by the skeleton. Pedaling forces are distributed over a greater muscular area resulting in less fatigue and an easier, faster transition from bike to run. The Garside Study of triathlon/duathlon performance revealed that athletes were significantly faster on the run when positioned correctly compared to those who were not. Perhaps the biggest biomechanical gains from good bike position do not come on the bike, but n the run afterwards- and this is not accounting for any aerodynamic benefits.

Tom Demerly (both formally trained FIST certified triathlon bike fitters)do FIST certified fittings on existing bikes. For an appointment phone (313) 278-1350 or e-mail at sales@bikesportmichigan.com

 

© Tom Demerly, Bikesport Inc.
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