Aerobars and Arm Rests

Basics and Functionality

Aerobars differ fundamentally from conventional road bike handlebars. While classic drop bars promote an upright riding position, aerobars enable a stretched, low posture with closely positioned arms. This position drastically reduces the rider's frontal area – the most important factor for better aerodynamics in cycling.

Aerodynamic Advantages

The main advantage of aerobars lies in reducing air resistance. Studies show that an optimized aerobar position can reduce the CdA value (aerodynamic drag coefficient multiplied by frontal area) by 15-25%. At a speed of 40 km/h, this means a time saving of approximately 2-3 minutes on a 40-kilometer course.

Biomechanical Aspects

The aerobar position not only changes aerodynamics but also the biomechanics of pedaling. The forward-leaning posture opens the hip angle and can improve power transfer with proper adjustment. However, this position requires good core stability and flexibility.

Types and Designs

Various aerobar systems exist that differ in construction, adjustability, and application.

Clip-On Aerobars

Clip-on aerobars are retrofittable attachments that mount on conventional road bike handlebars. They offer maximum flexibility and are ideal for triathletes and hobby riders.

Advantages:

• Easy installation on existing handlebars
• Cost-effective entry option
• Versatile adjustment options
• Quick switch between normal and aero position

Disadvantages:

• Higher total weight
• Less aerodynamic than integrated solutions
• Potential weak point in mounting

Integrated Time Trial Handlebars

In integrated systems, handlebars, stem, and aerobars are fused into one unit. These high-end solutions are used exclusively on professional time trial bikes.

Advantages:

• Optimal aerodynamics through seamless integration
• Lower weight through material optimization
• Stiffer construction for better power transfer
• Professional appearance

Disadvantages:

• Very high acquisition costs (800-2000 euros)
• Limited adjustment options
• Difficult adjustment for position changes
• Not retrofittable on standard road bikes

Ski-Bend vs. Straight Extensions

The arm rests (extensions) come in two basic forms:

Materials and Construction

The choice of material significantly affects weight, stiffness, comfort, and price.

Carbon

Carbon is the standard material in the high-end segment. It offers the best ratio of stiffness to weight and enables complex aerodynamic shapes.

Properties:

• Weight: 200-400 grams (complete)
• Stiffness: Excellent
• Comfort: Very good through vibration damping
• Price: 400-2000 euros
• Durability: Susceptible to crashes, otherwise long-lasting

Aluminum

Aluminum aerobars are more robust and cheaper than carbon versions. They are ideal for beginners and training bikes.

Properties:

• Weight: 350-600 grams (complete)
• Stiffness: Good to very good
• Comfort: Moderate - harsher vibration transmission
• Price: 100-500 euros
• Durability: Very robust, forgives crashes better

Hybrid Constructions

Modern aerobars often combine different materials: carbon extensions for low weight and aluminum arm rests for stability and easier adjustability.

Positioning and Adjustment

The correct aerobar position is crucial for aerodynamics, comfort, and performance. Professional adjustment through bike fitting is strongly recommended.

Arm Rest Width

The width of the arm rests should match the shoulder width or be slightly narrower. A position that is too narrow can impair breathing, while a position that is too wide brings aerodynamic disadvantages.

Guidelines:

• Narrow shoulders (38-40 cm): 12-14 cm arm rest spacing
• Medium shoulders (40-44 cm): 14-16 cm arm rest spacing
• Wide shoulders (44-48 cm): 16-18 cm arm rest spacing

Extension Length

The length of the extensions (arm supports) determines how far forward the upper body is tilted. Longer extensions enable a more stretched position but require more flexibility.

Height Adjustment

The height of the aerobars relative to the saddle affects torso tilt. Lower positions are more aerodynamic but more demanding for the core muscles.

UCI Rule Compliance

For UCI-regulated time trials, strict rules apply to aerobar geometry. The most important restrictions:

• 3:1 Rule: Tube profiles may be at most three times as long as wide
• Maximum Length: 75 cm from bottom bracket to front tip of aerobars
• Width Restriction: Maximum outside width 50 cm
• Cable Routing: Cables must be aerodynamically integrated

Installation and Mounting

Correct mounting of clip-on aerobars requires care and the right tools.

Tools and Materials

Required Tools:

• Hex key set (4-6 mm)
• Torque wrench (2-8 Nm)
• Spirit level or smartphone app
• Tape measure
• Carbon assembly paste (for carbon handlebars)

Step-by-Step Instructions

001. Preparation

• Remove handlebar tape in mounting area
• Clean and degrease handlebar surface
• For carbon handlebars: apply carbon assembly paste

002. Mount Base Plate

• Position clamp collars on handlebar (symmetrically)
• Tighten screws initially only hand-tight
• Check with spirit level that both sides are parallel

003. Attach Arm Rests

• Insert arm rests into base plate
• Rough position adjustment according to body measurements
• Provisional fixation (do not tighten completely)

004. Mount Extensions

• Thread extensions through arm rests
• Adjust angle and length
• Test ride for fine-tuning

005. Final Assembly

• Tighten all screws with torque wrench (4-6 Nm)
• Reattach handlebar tape
• Final function check

Care and Maintenance

Aerobars require regular inspection and care to ensure safety and function.

Regular Inspections

Before Each Training/Race:

• Check tightness of all screws (without retightening)
• Inspect arm rests for cracks or damage
• Check extensions for secure fit

Monthly:

• Check all screws with torque wrench for correct tightening torque
• Inspect clamping points for wear
• Examine carbon parts for hairline cracks (tap test)

Annually:

• Complete disassembly and cleaning
• Replace wear parts (pads, clamps)
• Have carbon parts professionally checked

Cleaning

• Use only mild soap solution
• No pressure washers (water pressure can penetrate connections)
• Never treat carbon with aggressive cleaners
• Rinse thoroughly with fresh water after saltwater contact

Typical Wear Signs

Training with Aerobars

The aerobar position requires specific training to adapt muscles and coordination.

Adaptation Phase

Week 1-2:

• Only short intervals (5-10 minutes) in aero position
• Focus on relaxed shoulders and natural breathing
• Flat courses without technical descents

Week 3-4:

• Longer intervals (15-20 minutes)
• Introduction of light climbs
• First short time trials (10-15 km)

Week 5-8:

• Continuous rides up to 60 minutes
• Integration into normal training rides
• Technique training: drinking and nutrition in aero position

Specific Exercises

Core Stability:

• Plank variations (3x 60 seconds)
• Side plank (3x 45 seconds per side)
• Forearm plank with leg raises

Flexibility:

• Hip opener stretches
• Back extension (cobra position)
• Shoulder mobilization

Riding Technique:

• Practice line holding in aero position
• Cornering from aerobars
• Train emergency braking (quick grip to main handlebar)

Buying Advice

The choice of the right aerobars depends on application, budget, and personal requirements.

Beginner Setup (100-300 euros)

Recommended Products:

• Profile Design T2+ Aluminum (approx. 120 euros)
• Bontrager Bzzzkill Alloy (approx. 180 euros)
• Vision Trimax Aluminum (approx. 150 euros)

Characteristics:

• Aluminum construction
• Straight extensions
• Good adjustability
• Robust and low maintenance

Mid-Range (300-800 euros)

Recommended Products:

• Profile Design Aeria Ultimate (approx. 450 euros)
• 3T Aura Pro (approx. 600 euros)
• Zipp Vuka Clip (approx. 550 euros)

Characteristics:

• Carbon extensions
• Ski-bend possible
• Optimized aerodynamics
• Light weight (300-400g)

High-End (800-2000 euros)

Recommended Products:

• Vision Metron 5D (approx. 1200 euros)
• Zipp Vuka Stealth (approx. 1600 euros)
• Profile Design Aerobar Sonic/Ergo Ultimate (approx. 900 euros)

Characteristics:

• Fully carbon
• Integrated cable routing
• Maximum aerodynamics
• UCI compliant
• Professional level

Buying Criteria Checklist

• Application: Time trials (UCI compliance), triathlon (more freedom), training
• Adjustability: The more options, the better the fit
• Compatibility: Fits handlebar diameter (31.8 mm standard)
• Arm Pads: Replaceable and comfortable
• Weight: Under 400g for carbon, under 600g for aluminum
• Warranty: At least 2 years, better 5 years for carbon

Common Problems and Solutions

Numbness in Hands/Arms

Causes:

• Too much weight on arm rests
• Incorrect arm pad height
• Too narrow elbow angle

Solutions:

• Strengthen core muscles
• Lower arm rests
• Lengthen extensions
• Use gel pads

Back Pain

Causes:

• Too aggressive position (too low/stretched)
• Weak core muscles
• Too little adaptation

Solutions:

• Raise arm rests
• Intensify core training
• Gradual adaptation
• Possibly shorter extensions

Unstable Steering Behavior

Causes:

• Extensions too long
• Leaning too far forward
• Lack of practice
• Too loose mounting

Solutions:

• Shorten extensions
• Mount arm rests further back
• Riding technique training
• Check screws with torque

Technological Trends

Aerobar development is characterized by constant innovation and improvement.

Current Developments

Integrated Electronics:

Modern aerobars increasingly integrate switches for electronic shifting directly into the extensions. Profile Design and Zipp already offer systems with integrated Di2 or AXS switches.

3D-Printed Customizations:

Some manufacturers offer 3D-printed, personalized arm rests that fit exactly to the rider's hand and arm shape. This improves comfort and aerodynamics simultaneously.

Sensor Integration:

Aerobars with integrated pressure sensors can measure weight distribution and help optimize position. This technology is still in its infancy but is already being tested by professional teams.

Future Outlook

Expected Innovations:

• AI-based position optimization through real-time data analysis
• Even lighter materials (under 200g for complete system)
• Variable geometry (adjustable during ride)
• Haptic feedback for optimal position
• Even stricter UCI regulations for cost capping

Related Topics

For a comprehensive understanding of time trial equipment, we recommend the following related articles:

• Time Trial Bikes - Complete overview of time trial bike technology
• Special Features of Time Trial Bikes - Specific properties and construction
• Individual Time Trial - Tactics and strategy in time trialing
• Aerodynamics in Road Bikes - Basics of aerodynamics in cycling
• Aerodynamic Position - Optimization of riding position

Last Updated: November 12, 2025