Body Position and Aerodynamics on a Bike

Aerodynamics has really dominated the talk of bike tech for the last decade or so, but even if we couldn’t quantify it, riders have known how important aerodynamics is to cycling. If you don’t believe it, think back to when you went really hard in a race, after a kom, or just tried to get through a stiff headwind section, you flattened your back, maybe got in the drops, and tried to get as small as possible. Even the great Eddy Merckx knew that getting down in an aero position would be an advantage, even if they didn’t know what to call it or why it worked.

Body position plays the biggest role in the aerodynamics of a bike rider. Bigger than the aero frame, the wheels, skinsuits, etc, the body position is massive. Understanding your overall cycling posture and riding position is essential not only for speed but also to help most riders stay relaxed and ride comfortably on both short efforts and long rides. Finding the perfect riding position is always a balance between aerodynamics, comfort, and power, much like achieving an efficient bike fit.

Here, we are going to look at how to position yourself and when to minimize your aerodynamic drag.

Aerodynamics And Speed

The speed at which you are riding, or more accurately, the wind speed (the net speed of riding speed plus wind speed), is going to determine how big an impact aerodynamics has at any given time. If you are riding into a 10 mph headwind, it will make it significantly more important, but if you have a 10 mph tailwind, it is a good opportunity to sit up, get a drink, some food, etc, because the aerodynamic effect is lessened in the tailwind. We discuss this further in our other blog post, 'Why Aerodynamics Matters at All Speeds.' For this post, we will look at how big an impact position has and when each kind of position might be a good idea.

For most riders, the main concern is knowing when to adjust their bicycle position so they maintain efficiency and balance over long distances.

The Hoods

Riding with your hands in the hoods is often the baseline of what we think when riding a road, gravel, or cross bike. It is the most comfortable for many, gives you easy access to braking, shifting, and great control on the bike. It also promotes a more upright position, which helps riders ride comfortably during recovery sections or steady long rides.

The issue here is that it is a fairly large aerodynamic penalty compared to other positions on the bike. We will use this as our aerodynamic baseline for comparison. Since it is the slowest position, it's best to spend as little time here as possible. Because your elbows stay slightly bent on the handlebars, this posture generally offers stability, even if it's not the best choice when you want to ride faster.

If you need some relief from a less comfortable position, are eating, etc, and this is the ideal position to do it, try timing it with a tailwind section of the course or when you are in a big group that is breaking the wind for you. This will drastically reduce the effective wind speed that you are experiencing and minimize any aerodynamic penalty you are facing. If you are in a group, this or the next position on the list is probably your go-to since you have easy access to the brakes and shifting.

The Drops

This is the classic position when you think of getting aerodynamic on a bike. Hands down in the drops, trying to get a flat back, and still have all the control of your brakes and shifting. This is a great way to save some energy while still staying pretty comfortable. This riding position reduces frontal area and is often part of a perfect fit for riders who want to ride faster without compromising control.

Compared to our drop's position at 40kph/24.8 mph, we saw a 19.6W advantage! That is massive. If you were solo over 10 miles, that is a savings of 35 seconds. It is more of a savings than being in the hoods and is best used as a position to be held for long periods of time, or to conserve a bit of energy within the group. If you are going for that solo flyer, keep reading down the list, and you will certainly find some better positions to aim for.

Aero Hoods

This is what I would call the sweet spot for most solo efforts. If you are in road racing, it is still a UCI legal position, you are in control of steering, and can hold it for extended periods of time. Your hands on the hoods, but forearms horizontal, back flat, trying to minimize your frontal area as much as possible. Since your hands are still on the hoods, you get most of the control of the bike, but with the frontal area being reduced, we saw a 46W gain over the hood's position. That equates to a minute and 9 seconds of savings over the hood's position for the 10-mile solo move.

The aero hood's position is not something you would want to do in a group since you lack the ability to hit the brakes, but if you are on the front or solo, this is absolutely a good way to save some energy or go a little faster. There is another position that is a little faster, but you will give up a lot of control, and if you happen to be in a UCI race, it will trigger a few hundred Swiss Francs fine.

Puppy Paws/T-Rex Arms

Resting your forearms on the hoods has been really popular the last few years for the breakaway artists on the road. It is so fast that the UCI decided to come in and ban the position for safety reasons. When we tested this position, we saw a 51W savings over the hood's position at 40kph. In that same 10-mile solo move, you should see something like another 7 seconds over the aero hoods or 1:16 over the hoods position.

For most riders, this is not the perfect riding position because maintaining balance and control becomes the main concern. Unless you train in that position all the time, it will likely make you sit up quicker and ultimately be slower. If you have some smooth tarmac and an open road ahead of you, maybe this is the time to use this position. If the puppy's paws' position gets a little controversial, our next position will make half the riders roll their eyes into the back of their head.

Aero Bars

There is a reason that time trialists and triathletes use aerobars; they are hands down the fastest position on a bike. This position maximizes aerodynamics but typically requires careful bike fit adjustments if you want to stay relaxed and avoid issues such as knee pain on long distances.

We tested the Factor Ostro Gravel that has a bolt-on aerobar option. When we rode in the bars, it saved just shy of 62w at 40kph! That is absolutely massive. If the event you are doing allows the use of aero bars, it can be an enormous savings. When we use the same 10-mile solo effort at 40kph that saves a minute and 28 seconds, 1:28!

We talk about this in our blog post about aerodynamics at slow speed, but if you are going slower into a headwind, the aerodynamics are even more important. If you are doing 180w into an 18 mph headwind, we are all familiar with how hard and slow that ride is going to be. For a 180 lbs rider, you would be doing about 11-12 mph in the hoods. Because you are going 12 mph and the wind is 18 mph, all of the aerodynamics are acting like 30 mph. That brings the aerobar savings to 120W or 14:11. That is 14 minutes and 11 seconds faster when you face that headwind.

Takeaways

We think all of these tests are really interesting, but how do you implement them for your own race? For most of us, age-group recreational athletes, we aren’t competing for an overall win at a big race, but we are trying to complete it and maybe even beat a previous time. Focusing on optimizing your setup for when it matters most is key. The last example with aerobars into a headwind is the most dramatic because you are actually moving fairly slowly, but you get a massive benefit. Anytime you have a huge headwind like this, it is essential to get yourself into a more aerodynamic position, whether that be aero hoods, drops, or aero bars if you have them. This will give you the biggest gains for the given sector.

When you turn around and have that big tailwind, go ahead and sit up to rest your back, drink plenty, eat, and make sure you are following the most efficient line on the road. Aerodynamics is relative to the cube of speed, but rolling resistance is constant. If you are going 20 mph with an 18 mph tailwind, rolling resistance quickly becomes a much larger percentage of what is slowing you down.

By focusing on the biggest factors at any given time, you can save a larger amount of time on the course than if you look at just the average speed and the savings at that speed. Ultimately, the perfect riding position is the one that suits your goals, your event, and your body. A proper bike fit ensures your bike is in a more comfortable position, helping you maintain balance and power throughout your ride.

Take a look below at our graph of body position and all of the savings at different speeds on our Factor Ostro Gravel bike. Let us know how you are planning to use this testing to optimize your position for your next big event.