Training > Bike

Aero Biking Part One

Developing an aerodynamic position is vital for quicker biking. All you need is the correct set-up and some specific stretches, says Dave Smith

Fact: making you and your bike more aerodynamic will speed up your cycling and, potentially, help you conserve energy for the run. “But that’s blindingly obvious,” we hear you cry. True, but achieving the streamlined effect isn’t quite as crystal clear. That’s why over two parts we’ll show you how to shave minutes off your cycle leg by becoming stealth-like. Next month focuses on the gear that cuts through the marketing hype – and the air. This month, however, it’s all about you and how you can comfortably achieve the aerodynamic position.

Overcoming physics

Sadly, it’s not as simple as placing you into an aerodynamic position and sending you out to collect medals. First up, you need to understand what obstacles are in your way on the path to aerodynamic excellence.

To find the most effective position on your bike, you need to think of your body as being divided into four parts – head, arms, torso and legs. Each zone presents unique problems, limitations and solutions in the quest for a performance-boosting position. As you move through the air, different parts of your bike and body will experience both frictional and pressure drag.

Frictional drag refers to the friction caused by air sliding past the skin, clothing or bike. Pressure drag occurs when a sharp face is presented to the wind, creating differences in air pressure; in other words, we’re talking about turbulence.

In fact, the effect of air resistance on a cyclist is so pronounced that adopting an aero position, which can actually place greater stress on your physical capability, is the ideal. “Hang on, getting aero drains us of energy?” we hear you cry once more. Let us elaborate… Getting aero can actually result in a decrease in physiological efficiency and an increase in the metabolic cost – with a consequent reduction in the average power output of the cyclist.

Here’s an example… Research at the University of Bern found that an aero position placed an additional metabolic burden of 9 watts on a rider. However, set this against the fact that the aero position gave the rider-and-bike unit a saving of 100 watts – in other words, they’d actually travel further for less effort – and you can see why it’s a no-brainer.

So what does this mean in real terms? Well, how does 6-8% over 40km sound? An athlete whose fitness and nutritional states remain stable yet adopts an aero position over a road-racing position can expect to cut as much as 4-5mins off a 60min 40km time. Some studies suggest an overall advantage that is equivalent to gaining 90 watts of power output. In short, enhancing an already aero position may gain you a few minutes on the bike and help you run faster, too.

The aero options

We’ve shown you the time benefits of getting lower on your bike, but what’s the best choice when it comes to your front end? For more than 100 years, road cyclists have used ‘drop bars’ to reduce their frontal area. Doing so enables the rider to increase their speed and efficiency over time. The classic road drop-bar position, with hands wide apart, eliminates some drag by lowering the torso, but creates some new drag with the arms and chest acting like a parachute.

The actual bar system you choose as a triathlete will come down to the type of events you’re planning to race. For most short-course events (Olympic-distance and lower), a time-trial bar with aerodynamic attachment will be most suitable and adaptable. On longer events, on easy courses, you may wish to have a slightly higher position for comfort when in the aero position for extended periods.

When competing in events with mountain climbs and descents, a traditional road drop bar with aero attachment will give you the option of climbing with your hands on the brake hoods. This gives good aero position, but more confidence and control on tight turns than an aero tuck.

Whatever you choose, you won’t receive any benefits if your bike’s not set up correctly and your body isn’t tuned to the position…

Bike set-up

Research shows that an athlete’s metabolic stress is generally increased by reducing the trunk to femur angle. That means, if you lower your elbow position, you may need to move the saddle forward to maintain your trunk to femur angle while assuming a lower, almost horizontal torso position.


Like all things there’s a degree of choice. For example, a flat bar position will aid aerodynamics, while bars angled upwards will assist the physiological aspect of performance – you need to experiment with the set-up and find what works best for you.

The move to steeper seat-tube angles on tri bikes, away from the more laid-back angles of traditional road cycle frames, has been driven both by this need to maintain a functional trunk to femur angle and to ‘mimic’ the muscle activity of the run by greater hamstring involvement. However, a less steep seat-tube angle may help preserve some hamstring capacity for the run.

We’ve explained how to achieve set-up in the ‘Getting aero’ section below, but here’s what you should do in a touch more detail… (Initially, set up your position on a turbo trainer before you test it on the road.) Ideally, your forearms should be slightly extended and close to level, with your back flat or tilting slightly down at the front. Your shoulders should be as low as possible and your elbows close together.Yet, as ever, you will have to make some compromises – for instance, a narrow elbow width may be more suitable for an experienced rider as it will have a negative affect on your ability to steer.

An excellent position is with your upper arms at 90° to your torso and your femur at 90° to your torso at the bottom of the pedal stroke. Until you’re flexible enough to do this, choose aerobars that you can easily adjust.


To check the efficiency of your position, do some simple hill tests. Find a ¼- to ½-mile straight hill that’s steep enough to get up a speed of about 30mph without pedalling – the base of the hill should lead into another hill so that you can slow down. Roll off at the same point on the hill and down the slope, marking where you stop each time as you adjust position – keep your knees tucked in and cranks at the 3 and 9 o’clock position. The most aero position is the one that sends you the greatest distance.

Body set-up

To achieve an aero position, think low and narrow. A low, close-to-horizontal torso, with narrow elbows and knees that are as close to the bike as possible will give you the aero effect that you desire. If only it was so simple…

There are a few factors that affect how aero you can go. Firstly, the physical structures of joint and muscles can be limiting. You may find that the extra 3cm of movement needed to reduce the space between your elbows is restricted by the mobility of your shoulder joints. This may be down to a lack of flexibility or, indeed, an old injury. Fortunately, joint mobility can be enhanced through specific stretching exercises (see the box on Improving your aero flexibility above).


As previously mentioned, any aerodynamic gains must be balanced against any additional metabolic cost. If the function of the diaphragm and intercostal muscles is compromised by a restricted position on the bike, you’ll find your desire to breathe outweighs your desire to slice through the wind.


You can calculate the physiological cost with a cycle ergometer or a similar device that measures power. As you experiment with different positions, ride at a set power output and make note of heart rate in each. Obviously a high power output at a low heart rate is the optimum.

How it will help your running

In a study published in the Journal of Sports Sciences in 2000, Ian Garside and Dominic Doran examined the biomechanical effects of an aero position on the run phase. The results showed that there were huge time savings for athletes running off the tri bike. An average of 5mins was saved on the 10km run when the athletes transitioned from a tri bike as opposed to a road bike.

So, as you can see, getting aero is pretty much essential if you want to improve your bike and run performance. With a bit of patience, a friend who’s happy to have a look at your position on the bike and a regular regime of stretching, you should be able to slice through the air with less turbulence while slicing your times. 


Getting aero


1 Put your bike on a turbo trainer, adjust the bars so that there’s a 90° angle between upper arm and torso. Make sure your forearms are parallel to the ground.


2 Adjust the seat position to create a 90° angle between the femur and torso at the bottom pedal position.


3 If necessary, do the stretch exercises shown in the 'Improving your aero flexibility' box below over a period of 3-4 weeks until you’re able to adapt to the position easily and naturally.


4 Use a power device and heart rate monitor to establish the ‘cost’ of the position in heart rate (HR) at a set power output.


5 Use a rolling hill test to fine tune your position until you’ve found the most effective aero position for you.


6 Finally, double check how this affects your HR to assess the physical cost of adopting the aero position.

Dave Smith has been a cycling coach for over 20 years. His clients have included Tour De France cyclists and Olympic medallists

IMPROVING YOUR AERO FLEXIBILITY

How do you prepare your body to adopt an aero position? Unless you’re already pretty flexible, some regular stretching sessions will be of immense benefit. Eventually you’ll be able to lower your torso and bring your elbows closer together.

You’ll need to focus on three key areas: the shoulders and upper arms; lower back (core musculature); and hamstrings. More flexible muscles not only allow for better positioning but are less energy demanding – tension has an energy cost. When on the bike, you want to make sure that the engine gets the bulk of the energy on tap and that as little as possible is diverted to the postural muscles working hard to maintain a good position.

You should aim to do 2 sets of each stretch, holding them for 10-15secs. Do this every day without rushing through the routine; indeed, stretches should be integral to your training, not just than afterthought.

1 Stand up straight Gently clench your fists and bring them together just beneath your chin. Raise your hands until your upper arm is at a 90° angle to your torso. Then slowly bring your elbows together. You should feel a stretch across the top of your shoulders and between your shoulder blades. Hold for 10secs, then relax.

2 Raise your right arm straight out to the side Slowly bring it across your chest. Take hold of the upper arm with your left hand and push gently to increase the intensity of the stretch. Hold for 15secs, relax and repeat on the left side.

3 Kneel in front of a stability ball and place your arms on the ball in an aero position as shown. Make sure that your elbows are the correct distance apart. Now, slowly roll the ball forwards and then from side to side. You should be able to feel a stretch along the side of your torso.

4 Balance in a plank position with your thighs on a stability ball and place your arms in the aero position on a bench in front. Rock from side to side, keeping your arms still. You should feel a stretch down the side of your torso. Change your position on the ball so that you’re balancing on your knees. Again, rock from side to side.

5 Place your right hand behind your head and reach your hand down your back. Take hold of your right elbow with your left hand and gently pull back on the right elbow to increase the stretch through the triceps. Hold, relax and repeat on the other side

6 Wrists and fingers are often overlooked in mobility training. However, the forearms are a complex maze of muscle and tendon and finger stretches are the best way to target them. Raise your right arm in front of your chest. Take hold of one finger at a time and gently pull towards the elbow. Hold the stretch, relax and then repeat on the other fingers.

7 Next, tilt your hand upwards in the opposite direction. Gently pull each finger towards the wrist in the same way as you did before.

Repeat stretches 6 and 7 on the left arm

8 Sit on the floor with your legs crossed. Place your fingertips on your shoulders, chin on your chest and slowly curl your shoulders down towards your hips. When you can feel a stretch across your upper back, slowly rotate your right shoulder towards your left hip. Hold and then repeat on the other side.

9 Lie on your back and draw your knees to your chest. Take hold of your legs behind your knees and gently pull them towards your chest to feel a stretch in your lower back.

10 To stretch your hamstrings sit on the floor, and slide your hands down your legs until you feel the stretch. To enhance the stretch, have someone place their hands on your shoulders and lean back hard into them for a few seconds before reaching forwards.


 
 

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