Aerodynamic Position in Time Trials

Fundamentals of Aerodynamics

At speeds over 30 km/h, air resistance is the dominant force a cyclist must overcome. While rolling resistance and friction remain relatively constant, air resistance increases exponentially with speed.

Air resistance is determined by three main factors:

• Frontal Area: The projected area of the rider and equipment against the direction of travel
• Streamline Shape: How smoothly air can flow around the body and bike
• CdA Value: Product of drag coefficient (Cd) and frontal area (A)

The Perfect Time Trial Position

Upper Body and Torso

The core elements of an aerodynamic upper body position:

001. Horizontal Back
The back should run as parallel to the ground as possible. The flatter the upper body, the smaller the frontal area. Professionals often achieve back angles of 0-5 degrees to the horizontal.

002. Lowered Shoulders
Raised shoulders increase the frontal area. The shoulders must be relaxed and rotated forward to minimize air resistance.

003. Narrow Elbow Width
The forearms should be as close together as possible, ideally shoulder-width or narrower. This significantly reduces the frontal area.

Head Position

001. Minimized Frontal Area
The head is one of the most aerodynamically unfavorable body parts. The optimal head position:

• Look 3-5 meters ahead of the front wheel
• Chin close to the stem
• Neck relaxed despite lowered head

002. Aero Helmet Integration
Modern time trial helmets are optimized for a lowered head position. The characteristic tail must be aligned parallel to the airflow.

Leg Work and Hip Position

001. Closed Knee Alignment
The knees should pass as close to the frame as possible. Outward knees disrupt airflow and significantly increase resistance.

002. Hip Rotation
The hips must be rotated forward to enable the flat back. This requires sufficient flexibility in hip flexors and hamstrings.

003. Saddle Height and Position
For the time trial position, different rules apply than for road riding:

• Saddle often 1-2 cm further forward
• Slightly lower saddle height possible
• Optimization between aerodynamics and power transfer

Equipment Setup

Aerobar Adjustment

001. Pad Height
The pads should be positioned as low as possible without compromising performance. Typical height differences to the saddle:

• Beginners: 6-10 cm lower
• Advanced: 10-15 cm lower
• Professionals: 15-20 cm lower or more

002. Pad Distance
The distance between the pads determines elbow width. Tighter positions are more aerodynamic but can restrict breathing.

003. Extension Length
The extensions should be positioned so that the forearms run approximately horizontal and the hands comfortably reach the grips.

Frame Geometry

Training Methods for Aero Position

Flexibility Training

Position Training

001. Progressive Adaptation
The aerodynamic position must be developed gradually:

• Week 1-2: 5-10 minutes in aero position per ride
• Week 3-4: 15-20 minutes at a time
• Week 5-8: 30-45 minute aero intervals
• From Week 9: Complete time trials in aero position

002. Power Retention in Aero Position
Conduct regular FTP tests in time trial position. Power in aero position is typically 5-10% below road position but should converge with training.

003. Muscle-Specific Training

• Core stabilization for long-term position maintenance
• Neck muscles for relaxed head position
• Hip flexor strength for forward-rotated hip position

Wind Tunnel Testing and Optimization

Professional Aerodynamics Testing

001. CdA Value Measurement
The drag coefficient multiplied by frontal area (CdA) is the key metric:

• Elite time trialists: 0.20-0.25 m²
• Good amateur time trialists: 0.25-0.30 m²
• Average riders: 0.30-0.35 m²

002. Iterative Optimization
In the wind tunnel, the following parameters are systematically varied:

• Elbow width (in 2 cm steps)
• Back height (in 1 cm steps)
• Head position (various angles)
• Helmet selection and position
• Racing suit material and cut

Field Testing Alternatives

For riders without wind tunnel access, there are practical alternatives:

001. Chung Method
Mathematical procedure for calculating CdA based on power and speed data on uniform terrain under various wind conditions.

002. Virtual Elevation Test
Comparison of climbs on identical terrain with different positions to determine the most efficient setup.

003. Notio Aerosensor
Device for real-time CdA measurement during riding, providing continuous feedback for position optimization.

Common Mistakes and Corrections

Critical Position Errors

Comfort vs. Aerodynamics

001. The 80% Rule
Many athletes achieve the best overall result with a position that offers 80% of the maximum possible aerodynamic improvement but maintains 95-100% of power output.

002. Don't Restrict Breathing
Too narrow elbows can reduce lung capacity. In time trials over 20 minutes, breathing efficiency becomes critical.

003. Sustainable Position Maintenance
The position must be maintainable for the entire time trial duration. A position that can only be held for 10 minutes is useless for longer time trials.

Special Cases and Adjustments

Mountain Time Trials

For time trials with significant climbs, modified rules apply:

001. Less Aggressive Position
On climbs, speed decreases, making aerodynamics less important. A slightly more upright position can enable more power here.

002. Position Changes on Climbs
Many professionals switch from aero pads to aerobar grips or even to the tops on climbs for more power.

Team Time Trials

In team time trials, there are special considerations:

001. Homogeneous Team Position
All riders should have similar CdA values to enable even rotations.

002. Optimize Lead Work
The leading rider should adopt the most aggressive aero position, following riders benefit from drafting.

Weather Influences

Scientific Fundamentals

Power Calculation

The required power in time trials consists of:

P_total = P_air + P_roll + P_mechanical + P_elevation

Where at constant speed on flat terrain dominates:

P_air = 0.5 × ρ × CdA × v³

This explains why small CdA improvements at high speeds bring disproportionate time gains.

Boundary Layer Theory

001. Laminar vs. Turbulent Flow

• Laminar flow: Ordered, low resistance
• Turbulent flow: Chaotic, higher resistance
• Transition: The transition is critical

002. Trip Technology
Modern racing suits use small surface structures to influence the boundary layer:

• Dimpled materials on arms and legs
• Smooth materials on torso and head
• Strategically placed seams

Practical Implementation

Step-by-Step Optimization

Monitoring and Adjustment

001. Regular Position Checks
Photo comparisons every 4-6 weeks to detect gradual position changes.

002. Seasonal Adjustments
After winter training breaks, flexibility may be reduced. Make position adjustments in spring.

003. Competition Preparation
In the 2-3 weeks before important time trials, no longer change the position.

Material Optimization

Racing Suit Selection

Helmet Optimization

Helmet selection and position is critical:

001. Helmet Type for Head Position

• Lowered head position: Long-tail helmets (e.g., Giro Aerohead)
• Moderate position: Medium-tail helmets (e.g., Specialized TT5)
• Higher position: Short-tail helmets (e.g., Kask Mistral)

002. Helmet Position
The helmet must be aligned so that the aerodynamic tail runs parallel to the airflow. Even a 10° deviation can negate the advantage.

Related Topics

• Pacing - Optimal power distribution in time trials
• Aerobars and Pads - Equipment setup for time trialists
• Aerodynamics - Fundamentals of road bike aerodynamics
• Aerodynamics Research - Scientific developments
• Biomechanics: Saddle Position - Biomechanical fundamentals

Last updated: November 2, 2025