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
