Why a triathlon bikefit goes far beyond “sitting well on the bike”

Within the triathlon world, everything revolves around efficiency. Not only aerodynamic, but above all biomechanical and physiological. A fast position that your body cannot support will sooner or later become a limiting factor. Power loss, asymmetries, overload and even a lack of oxygen in certain muscle groups can, in the long term, make the difference between performing… or surviving.

At Bikefit Van Staeyen, we therefore look not only at the position on the bike, but at the full interaction between body, bike and performance. Every triathlete moves differently. Every body compensates differently. And that is precisely where real performance fitting begins.

Over the past few weeks, we worked with several triathletes and performance athletes for whom biomechanics, stability and data analysis were central. Three cases perfectly demonstrate why a modern bike fit today goes far beyond a “comfort adjustment”. For the first time, we give an inside look at the bike fit of a professional triathlete, a triathlete with great ambition, and a recreational triathlete who will do a full Ironman.

Nick Thijs - professional triathlete

Combining aerodynamics with physiology

With Nick we worked on a TT setup, combining various technologies to create not only an aerodynamic, but above all a sustainable racing position heading towards Klagenfurt.

One of the most important tools during this session was NIRS (Near Infrared Spectroscopy). With it we measure real-time muscle oxygenation and oxygen saturation during exertion. This allows us to objectively analyse how efficiently muscles function within a given position.

Small changes in:

• arm angle

arm angle

• hip angle

hip angle

• reach

reach

• crank length

crank length

• shoulder stability

shoulder stability

immediately produced measurable differences in:

• muscle load

muscle load

• oxygen use

oxygen use

• stability

stability

• power build-up

power build-up

And that is exactly what modern triathlon bike fitting is about today: not simply “lower and aero”, but creating a position that the body can genuinely sustain over long distances.

An aggressive position that is not biomechanically stable often costs more energy than it gains aerodynamically.

By combining biomechanics and physiological data, we were able to position Nick in a much more stable, efficient and sustainable TT posture, without sacrificing speed. Nick is more than ready for his next goal: the Ironman in Klagenfurt.

Lenie Boons

The body never lies..

With Lenie we saw clear asymmetries off the bike that directly influenced the position while cycling.

The pelvis stood clearly lower on the left, with a compensatory curvature in the spine. In addition, the right foot dropped more inward, causing the right leg to fall more into a valgus position (“knock-kneed”).

The result? Compensations throughout the entire chain:

• rotation of head and upper back

rotation of head and upper back

• asymmetrical loading

asymmetrical loading

• pressure differences on saddle and pads

pressure differences on saddle and pads

• loss of stability

loss of stability

On the bike we saw more pressure on the saddle on the left, while more support was sought on the aeropads on the right. The body always tries to find a way to keep itself stable.

Through a number of external compensations, combined with a correct saddle height and setback, the entire movement pattern changed.

Suddenly we saw:

• more symmetry

more symmetry

• less pelvic movement

less pelvic movement

• more stable trunk control

more stable trunk control

• calmer pedalling behaviour

calmer pedalling behaviour

And that perfectly demonstrates why a bike fit is never only about the bike. The body always determines the position, not the other way around.

Michaël Van De Maele

Stability begins at the foot

With Michael we saw a completely different problem. Here the greatest limiting factor lay on the right side of the kinetic chain.

The right foot constantly sought stability during the pedalling cycle. In addition, the foot was clearly more in supination (outward), causing force transfers to run unstably and compensations to arise higher up.

What many athletes underestimate: the foot is literally the foundation of the entire riding position.

When instability arises there, the body starts to compensate:

• pelvic rotation

pelvic rotation

• asymmetrical pressure distribution

asymmetrical pressure distribution

• shoulder loading

shoulder loading

• reduced efficiency

reduced efficiency

• increased muscle activity

increased muscle activity

Through targeted support with a custom-made functional insole, we were able to make the lower chain much more stable.

In addition, the saddle was initially too high and the drop to the handlebars too aggressive. By correcting these parameters, the following arose:

• more calm in the pelvis

more calm in the pelvis

• better control of the trunk

better control of the trunk

• less overload

less overload

• more stable power transfer

more stable power transfer

Important here: a lower front position is not automatically faster.

When stability disappears, you often lose more watts than you gain aerodynamically.

Data are important. But interpretation is everything.

Today there are more and more tools:

• motion capture

motion capture

• pressure measurements

pressure measurements

• NIRS

NIRS

• saddle mapping

saddle mapping

• EMG

EMG

• video analysis

video analysis

• AI systems

AI systems

But technology alone does not make a good bike fit.

The real added value lies in:

• understanding compensations

understanding compensations

• listening to the athlete

listening to the athlete

• interpreting the data

interpreting the data

• combining biomechanics with performance

combining biomechanics with performance

Every triathlete has:

• a different mobility

a different mobility

• different asymmetries

different asymmetries

• a different load capacity

a different load capacity

• different physiology

different physiology

#movebetter #pedalfurther #bikefitting

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