REF-844 · Fintelman et al., 2014 · Journal of Biomechanics, Vol. · Paper · PubMed

Optimal Cycling Time Trial Position Models: Aerodynamics versus Power Output and Metabolic Energy

Cweak evidence: opinion or lab dataMeasured on a mixed groupWritten before October 2026, being re-checked

The authors built two models to find the torso angle that is best for a time-trial cyclist at a given speed: a Metabolic Energy Model that minimises the energy cost of riding and a Power Output Model that maximises the rider's power output. Inputs were measured in 19 TT cyclists at torso angles from 0 to 24°.

In both models the optimal torso angle fell as speed rose; aerodynamic losses outweighed power losses above 46 km/h, a fully horizontal torso was never optimal, and below 30 km/h a more upright TT position was better.

Participants

Input data from n=19 TT cyclists (abstract: "19 TT cyclists") measured at torso-angle positions of 0-24°. Sex, age and level are not given in the abstract.

Protocol

Two models to determine the optimal torso angle:
Metabolic Energy Model: minimises the energy expenditure required to ride.
Power Output Model: maximises the cyclist's power output.
Input parameters (drag and physiological response at each torso angle) collected experimentally in the 19 cyclists.
Output: optimal torso angle as a function of cycling speed, and the speed at which aerodynamic power losses start to dominate.

Key Results

The optimal torso angle depends strongly on cycling speed in both models: the faster the speed, the lower the optimal torso.
Aerodynamic losses outweigh the power losses at speeds above 46 km/h.
A fully horizontal torso is not optimal at any speed.
Below 30 km/h a more upright TT position is beneficial.
The two models did not give completely similar outputs; the authors suggest the Metabolic Energy Model for endurance events and the Power Output Model for sprinting or variable conditions (wind, undulating course).
The abstract gives no optimal angles, drag values or power losses in numbers.

Practical Application

In a model built on measurements from 19 time-trial cyclists at torso angles of 0-24°, the best torso angle fell as speed rose: aerodynamic losses outweighed the power lost to a lower position only above 46 km/h, below 30 km/h a more upright position was better, and a fully flat torso was never optimal. How low to go depends on how fast you ride: the slower the rider, the less a very low torso pays.
Do not put the whole field in the same position: a rider averaging well under the break-even speed gains more by keeping the power than by lowering the torso further.
Inference, not tested here: most amateurs ride a time trial well below 46 km/h, so for them the power side of the trade weighs more than in professionals; retest power in any lower position before racing in it (REF-793, REF-201).
The paper's own suggestion: on windy or rolling courses the power-maximising version of the model is the more suitable guide.

Limitations

Modelling study: the predicted optima were not validated with ridden time trials.
Input cyclists' level, sex and the measurement setting are not described in the abstract.
The two models disagree in part; the abstract does not say by how much.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

modelling: the inputs were measured, the predicted optimum positions were not tested on riders