The Safety in Numbers Effect

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Does the chance of a cyclist being involved in a fatal accident increase as the number of cyclists on the road increases? The answer may surprise you. While the raw number of cycling fatalities does increase as the number of cyclists on the road increases, the chance that any one of those cyclists is killed is likely to decrease. This negative correlation between the number of cycling fatalities and the number of cyclists on the road is called the safety in numbers effect.

Safety in mumbers

The graph above illustrates the safety in numbers effect by plotting the number of kilometers cycled per inhabitant along with the number of cycling fatalities for every billion kilometers traveled for various countries. The graph is from a research report published by the OECD (Organisation for Economic Co‑operation and Development) titled “Cycling Health and Safety.” The safety in numbers effect generally holds for pedestrians as well as cyclists.

OECD_LOGO_1The OECD report cautions against thinking that the negative correlation seen in the graph leads to the conclusion that increasing the number of cyclists causes a decrease in the likelihood of cycling fatalities. The report also mentions that there has not been very much research into the possible causes of the safety in numbers effect and goes on to suggest several factors that may be involved.

  • Awareness: The more cyclists there are on the road, the more drivers will be aware of them. The more aware drivers are of cyclists, the less likely they are to hit them.
  • Expectancy: The more cyclists there are on the road, the more drivers expect to see cyclists. The more drivers expect to see cyclists, the more likely they are to actually see them and avoid hitting them.
  • Collective vigilance: The more cyclists there are on the road, the more likely it is that potentially dangerous or threatening situations will be noticed by at least one of them. Those who notice potential threats will communicate this information to the other cyclists who then have a greater chance to avoid the threat.
  • Knowledgeable leaders: The more cyclists there are on the road, the greater the chance that at least one of them will be knowledgeable about route and traffic conditions. The knowledgeable cyclist may lead the others along safer routes.

It may also be the case that safety and the number of kilometers ridden are linked in a causal loop. The safer cycling is, the more people are likely to cycle, and the more people cycle, the more opportunity there is for awareness, expectancy, collective vigilance or knowledgeable leaders to have an effect in reducing fatal accidents.

Hovenring 3

The Hovenring in the Netherlands is the world’s first suspension bridge designed to allow cyclists and pedestrians to safely cross a busy highway intersection.

Another factor that almost certainly plays a role in both increasing the number of kilometers ridden and in reducing fatalities is the presence of a well-developed cycling infrastructure. The Netherlands, Denmark, and Germany, the three countries with the best fatalities to kilometers ridden ratios shown in the graph, also have exceptionally well developed cycling infrastructures.  The Netherlands and Denmark are especially notable in this regard. The United States, on the other hand, has generally lagged behind the rest of the developed world in building well-designed and well-maintained cycling infrastructure.  The better the infrastructure, the more people are likely to use it to cycle safely.

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Dutch cyclists

There is an additional factor to consider that is highlighted by the Netherlands which has by far the lowest ratio of fatalities to kilometers traveled of any of the countries shown in the graph. In addition to having an excellent cycling infrastructure, the Netherlands has a long-established cycling culture. As early as 1911 the Netherlands had more bicycles per capita than any other European country. When privately-owned cars became more affordable after Word War II, cycling became less popular as a means of transportation. As the safety in numbers effect would lead you to expect, this was accompanied by an increase in cycling fatalities. During the 1970s widespread demonstrations took place in the Netherlands protesting the number of child cyclists who were killed on the road. The government responded by restricting the use of motorized vehicles in cities and towns, building cycling infrastructure, and embarking on a program of safety education for both cyclists and drivers that placed the Netherlands at the forefront of countries that make serious efforts to incorporate cycling into people’s daily lives. Children in the Netherlands are taught how to cycle safely from a very young age; adults are tested on their ability to share the road with cyclists as part of the process of getting a Dutch driver’s license. According to a press release from the Netherlands Ministry of Transport, Public Works and Water Management, in 2004 the Netherlands was the only European country in which there were more bikes than people, and in 2007 26% of all trips made in the Netherlands were made by bike. As a society the Netherlands has embraced a culture of cycling and this has played an important role in producing both the very large number of kilometers traveled by bike per inhabitant and the very low number of cycling fatalities shown in the graph.

Any or all of these factors – a strong social and cultural history of cycling, the presence of an excellent cycling infrastructure, driver awareness and expectation, cyclist vigilance and leadership – may have a role to play in explaining the safety in numbers effect. The negative correlation between fatalities and the number of kilometers ridden is simple and easy to see, the causal factors that produce this correlation are complex and difficult to tease apart.

(This article has been cross posted to The Info Monkey.)

A Bike Share Map

DC bike share mapOver 700 cities around the world have implemented bike sharing systems that allow people to make use of public bikes for short trips within the city.  The motivation is to reduce air pollution, noise and vehicular traffic congestion while providing people with the health benefits that come from daily exercise (which has been shown to decrease the costs of city-provided health services). The bikes can usually be used for free or for very low cost.

Oliver O’Brien, a researcher in the Geography Department of University College London has built a bike-share map that tracks the locations of bikes in the bike share systems of about 100 cities throughout the world. You can start with a global map and then click on the city of your choice to check out the more-or-less current state of the bike-sharing stations in the city. For example, here are the maps for Washington DC, New York, London, Paris, and Rio de Janeiro.

The circles on the city maps represent bike-share stations with the size of the circle indicating the number of bikes it can hold and the color indicating how full it is. For bike-share systems that allow it, the map updates about every two minutes. Some systems don’t permit updating this frequently and for this reason O’Brien advises against using the map to find out if there is a bike or an open space for a bike near you at any given moment. Unfortunately, the map does not tell you how often each city updates.

bike share graphsThe bike-share map also has a tab that opens up a set of graphs showing how many docks are operating, how many bikes were in use and the imbalance in distribution of bikes over the system during the previous 24 hours.  In addition there is an animated version of the map that shows the docking station changes over the previous 48 hours which can be accessed from a tab at the bottom of the static map.

O’Brien has a blog that includes a post about the bike-share map in which he writes about things like where the data displayed in the map come from, and why some cities that have bike-share systems are not included on the map.

This article has been cross-posted to The Info Monkey.

Cycling and Weight Loss Part 2: Metabolic Homeostasis

scale_caloric_balanceThis is the second in a series of posts about losing weight on the bike. Throughout this discussion it’s important to keep in mind that eating has many consequences for health, athletic performance and weight loss.  The “best” diet for losing weight is unlikely to be the “best” diet for maintaining either your health or a high level of athletic performance.

In the first part of this series, Riding the Bike to Lose Weight, I pointed out that there is a modifying factor that affects the basic  relationship between caloric intake and weight loss.  The basic relationship is that if you ingest fewer calories than you burn during the course of a day, you will lose weight, if you ingest more than you burn, you will gain weight, and if caloric intake and caloric burn are about equal, your weight will remain stable.  The modifying factor is metabolic homeostasis.

If you’re not familiar with the jargon, “metabolic homeostasis” is incomprehensible and useless gobbledegook.  In the context of thinking about weight loss, “metabolic” refers to the chemical processes that are involved in the breaking down of food in the digestive system and the ways the results of that breakdown process, such as glucose, are used by the body.

A homeostatic system is one that acts to keep itself at an equilibrium point or within an equilibrium range.  A common example is the climate control system in your house or car.  You set the thermostat for a high and a low temperature and the climate control system keeps the temperature of your house or car within this range.  If it gets too hot, the air conditioning is turned on; if it gets too cold, the heat comes on.

The human body is a brilliant homeostatic system in a number of ways.  If the core temperature of the body gets too hot, you sweat to rid yourself of excess heat; if core temperature gets too cold, you shiver to generate more heat.  If blood glucose drops too low, the system reduces glucose uptake at the muscles to maintain glucose supply to the brain.  Cyclists in the heat of battle sometimes wish it didn’t work this way as they go into a bonk and their legs shut down.

caloric homeostasisMetabolic homeostasis refers to the body’s mechanisms for maintaining a balance between caloric intake and caloric burn.  This homeostatic system is more complicated than previously thought and much about it is currently not well understood.    I’ll try to summarize some of the issues that come into play when considering weight loss, exercise and metabolic homeostasis.

One thing that appears to be soundly supported by the available evidence is that the body adapts to a regular, sustained change in the relationship between caloric intake and caloric burn by reducing the number of calories needed to fuel the same amount of activity.  Here’s an example of how this works.  Suppose your caloric intake and burn are balanced; on a typical day your regular activities burned 2000 kilocalories and you ingested about 2000 kilocalories in food during the day.  Your weight would remain stable.  Then you go on a diet and ingest only 1800 kilocalories a day.  At first you would lose weight because the 1800 kilocalories you ingest is less than the 2000 kilocalories you burn each day.  However, if you stayed on this 1800 kilocalorie per day diet for a period of time, your body would adapt to that reduced caloric intake by enabling you to engage in the same activity you were doing every day before you began the diet while only burning 1800 kilocalories.  Once that happens caloric intake and caloric burn are balanced again and you stop losing weight.

Reduction-in-RMR-GraphA slightly more technical way to express this idea is that the basal metabolic rate will change to maintain metabolic homeostasis.  Roughly speaking, basal metabolic rate is the rate at which kilocalories are burned to support normal daily activity.  When the balance between caloric intake and burn is disrupted through dieting or exercise weight is initially lost because fewer kilocalories are ingested than are burned and the basal metabolic rate has not yet adapted to the change.  However, after a period of sustained dieting or exercise the basal metabolic rate adjusts to the reduction in kilocalories ingested (by dieting) or the increase in kilocalories burned (by exercise), a balance between caloric intake and burn is once again achieved, and weight loss stops.

Maintaining metabolic homeostasis through a reduction in basal metabolic rate means that there’s only so far you can go when trying to lose weight by dieting, exercise or both.  If you want to keep losing weight through dieting, you have to continue reducing the number of kilocalories you ingest every day.  If you want to continue losing weight through exercise such as riding the bike, you have to keep increasing the intensity of the exercise.

This is why it was recommended in Riding the Bike to Lose Weight that you continually try to ride harder, longer, faster, stronger every time out on the bike if you want to lose weight.  If the intensity of the exercise remains the same, basal metabolic rate will adapt to it and weight loss will stop.  If the intensity keeps increasing, basal metabolic rate will lag behind and weight loss can continue.

If this were the whole story about metabolic homeostasis it would be simple.  If you enjoy riding the bike, figure out ways to put more time and energy into riding the bike and forget about worrying about calories and weight loss.  You will be doing something you enjoy, you will be thinking about something you enjoy and you will most likely lose weight.  The hope is that when you get to the point where you are putting all the time and energy you can or want to into the bike, your weight will have dropped to a level you like.

Unfortunately, it’s not this simple.  Riding the bike (or any other form of exercise) makes you hungry, makes you want to eat more. In addition, men and women are affected differently by this increase in the desire to eat after exercise.  More on this in the next post in the series.

Aerodynamics Part 3: Shaving Your Legs

The day after I posted Aerodynamics Part 2 about some small and free or relatively cheap things you can do to reduce air resistance and drag I came across this video.

We’ve all heard that shaving your legs makes you faster.  Does it?  Check this out.

Over the 40 km length of their trial runs, differences in how hard the rider is going over relatively short periods of time may well be sufficient to account for the differences they observed and they don’t address how, or even whether, they controlled for differences in effort over the trials with and without leg hair. From what you can see in the video it seems pretty clear they didn’t use physiological measures to control for effort.  Looking at the set-up in the video I would guess average speed was used as a control but without more information no hard conclusions can be drawn.  However, the magnitude of the differences they observed certainly indicate shaving your legs is something worth exploring further if you want to reduce air resistance and drag.

Aerodynamics Part 2: Small Things That Reduce Air Resistance and Drag

PIC372688193Tony Martin won the UCI World Time Trial Championship in 2011, 2012 and 2013, and is the odds on favorite to win it again this year. He is an incredible bike rider and by all accounts an incredibly nice guy; he once caught and passed David Millar in a time trial and apologized to Millar as he went by. The picture is of Martin time trialing in full aerodynamic mode at the 2013 Criterium du Dauphine which is an eight-day race that Martin won on the basis of the insurmountable lead he built by winning the time trial.

If you want to minimize air resistance and drag as much as possible, you ride like Martin rides in a time trial. Unfortunately, this is beyond the reach of many riders for a number of reasons. First, it’s expensive. Between his bike frame, wheel set, skin suit, helmet, etc., Martin is moving well over $10K worth of gear in the photo. Next, an optimized wind tunnelaerodynamic position is difficult to accomplish. Differences in body mass and shape mean that the position that optimizes both aerodynamics and power output is different for every rider. Finding that position takes hours of iterative testing and refinement in a wind tunnel. In addition, a full aerodynamic tuck is difficult to maintain and usually takes many hours of practice to be able to hold for any length of time. Simply strapping a set of aerobars unto your bike isn’t going to do it. Finally, riding in an optimal aerodynamic position is difficult. The position is uncomfortable and the bike is more difficult to control when you’re stretched out on aerobars.

Although going full aero involves a significant investment of time, effort and money, there are a number of simple things you can do that will reduce air resistance and drag that are relatively easy and are either free or cost the price of a new jersey. Taken individually, none of these things will result in a huge reduction in air resistance but small things add up and they can make a noticeable difference over a long ride.

Get Low

The biggest single thing you can do to reduce air resistance without spending any money is to reduce the surface area on the front of your body that is exposed to the wind as you ride forward. It’s easy to do and you don’t need aerobars to do it. Bend at the waist and lean forward. The lower you get the better off you’ll be but almost any degree of forward lean will reduce the area of your torso that is exposed to the wind.

Tour of the Battenkill 2012This is easiest to do if you have road handlebars on your bike. Moving your hands from a position on the flat upper bar on either side of the stem to the brake hoods will bring you down a little bit. Keeping your hands on the hoods and bending your elbows will bring you down more. You can get fairly low with your hands on the brake hoods by bending your elbows to the point where you’re resting your forearms on the handlebars like the rider in the picture. You can usually get even lower by riding with your hands on the drops.

Elbows and Knees

PIC298104874While the exact elbow position for optimal aerodynamic riding depends on the rider’s body size and shape, it’s generally the case that tucking the elbows in is better than bending them out. Many riders, however, tend to bend their elbows out in a variety of circumstances. When you bend at the waist and lean forward to get low, make sure to pull your elbows in rather than bend them out. People also tend to bend their elbows out when they are leaning into a climb, working hard to maintain a strong tempo, gripping the bars tightly, or are just tired. Pay attention to where your elbows are and if they are flaring wide, bring them in.

Knee position is an aerodynamic factor that people sometimes miss because it’s usually not obvious in pictures of riders who are time trialing. Take a look at where your knees are relative to your body while you’re pedaling. If your knees are spread open so that they form a V-shape with your body, your legs are funneling air into your body and increasing the air resistance and drag you have to overcome. Ride with your knees pulled in toward the top tube on your bike. Obviously, you don’t want your knees banging into the top tube but closer to the tube is better than further away. When you do this, don’t accomplish the “knock-kneed” position by flaring your ankles out.

Your Jersey

Wear a tight jersey. If your jersey is loose or baggy, it is catching the wind and increasing air resistance by acting like a sail that is pulling you in the opposite direction. Don’t worry about what you look like. How you look in your exercise clothes may be a big deal for gym bunnies but for riders the big deal is how smart and how well you ride. If you’re overweight, you’re overweight; there are things you can do to change that but wearing a loose jersey isn’t one of them. Don’t worry about it. Ride smart.

???????????????Keep your jersey zipped up. Partially unzipping a jersey allows air to circulate around the upper body to the back where it is trapped by the jersey. It’s like strapping a sail facing the wrong direction on your bike. You would think this would be a no-brainer but you see riders all the time from beginners to pros who have expensive aero gear on their bike and who are trying to go fast with their jersey partially unzipped.

 

watts and wind resistence_ key pointsThe graph discussed in Aerodynamics Part 1 illustrates that air resistance is negligible when you are going slow but it quickly ramps up with velocity until it becomes the overwhelming force you have to overcome to move your bike forward. While all of the tips and techniques offered in this post have a small effect in reducing air resistance they are all easy to do. They are also either cost-free or cost, at most, the price of a new jersey. Small benefits add up and their combination can make the difference between a ride that is exhausting and a ride that is exhilarating.

Aerodynamics Part 1: Air Resistance



hard ridingYou’re riding along at a speed that takes some effort. It’s difficult. What makes it hard? What do you have to overcome that is demanding all that effort to maintain your speed? You ramp it up and go faster. Now it’s even harder and it takes even more effort to maintain the faster speed. Why is it harder? What changed?

When you’re riding your bike there are four factors that resist your forward movement. One of them is gravity but gravity only comes into play when you’re going uphill. You have to provide enough power to carry the combined weight of you and your bike upwards against the earth’s gravitational field. You want to fly up the hill but the earth says not so fast.

When you’re not going uphill, gravity is not doing much of anything to hold you back but it still takes effort to move forward and the faster you go, the more effort it takes. You’re fighting against three types of resistance: drive resistance, rolling resistance, and air resistance. They all take effort to overcome but air resistance is, by far, your biggest enemy.

Drivetrain or drive resistance refers to the force you have to apply to overcome the mechanical resistance coming from the moving parts of the bike’s drivetrain. This includes factors like friction from the chain moving through the teeth on your front rings and rear sprockets and the bearings in the bottom bracket of your bike. If you’re pedaling, you’re producing drive resistance. You can reduce drive resistance by keeping your chain clean and well-oiled and by replacing the bearings in your bottom bracket when they wear out.

Another way to eliminate rolling resistance

Another way to eliminate rolling resistance

Rolling resistance refers to the force you have to apply to overcome mechanical resistance coming from the parts on the bike that are not part of the drivetrain that are moving when you’re rolling down the road. This includes things like the friction of your tires on the road and the bearings in your wheel hubs. You can reduce rolling resistance by making sure your tires are not under-inflated and replacing the bearings in your wheel hubs when they wear out.

Air resistance refers to the force you have to apply to displace the air around you as you move forward. When you move forward your body and your bike are moving into a space that was occupied by air. It would be nice if the air saw you coming and got out of your way but it doesn’t work like that. The air resists and has to be pushed out of the way. As we will see, unless you are climbing a steep hill most of the effort you are putting into pedaling your bike is being used to overcome air resistance.

watts and wind resistence_ basicThe graph on the left contains a lot of useful information about where your effort is going when you’re pedaling a bike. The graph shows how much power (measured in watts on the ordinate or y-axis) it takes to move a standard racing or road bike forward at different speeds (measured in kilometers per hour on the abscissa or x-axis). The graph assumes an average sized rider, on an average bike moving forward on a perfectly flat surface – which doesn’t describe any of us with perfect accuracy when we’re out riding our bikes. For this reason, the exact numbers shown in the graph aren’t what is important. When applied to you or me at any moment in time on a specific ride the numbers are likely to be a wee bit off. However the general relationships shown in the graph will hold for all of us all of the time.

Three of the functions on the graph show the amount of power needed to overcome rolling resistance, drive resistance (labeled Drivetrain in the graph) and air resistance (labeled Wind). The fourth function (labeled Total) shows how much power is needed to overcome all three types of resistance combined. Read the graph by taking a velocity or speed shown on the x-axis and then seeing how much power must be applied to overcome rolling, drive, air or the total resistance at that velocity by the corresponding point on the y-axis. For example, at 12 kph (kilometers per hour which is about 7.5 miles per hour or mph) drive resistance is so small it barely registers and it takes about 10 watts of power to overcome rolling resistance and another 10 watts of power to overcome air resistance.

Looking at power in terms of watts may not seem very useful if you do not have a power meter on your bike that tells you how many watts you are producing as you pedal. Another way to look at power is to think of it in terms of effort. What the graph shows as an increase in power measured in watts, can be understood as an increase in the effort it takes to ride at a faster speed. In other words, the higher the power requirement, the more effort you have to expend.

What useful information can we get from the graph?

watts and wind resistence_ function typeFirst, note that the functions for rolling, drive and air resistance all increase with velocity. The faster you go, the more effort it takes to overcome each type of resistance. This isn’t very surprising. Everybody knows it’s harder to go faster and the graph just lets us know that it’s harder for three reasons: rolling, drive and air resistance all increase with speed.

Next, consider the shape of the functions. The rolling and drive functions are linear which means they are very close to straight lines. This tells us something useful. The increase in the effort you need to expend to overcome rolling and drive resistance as you go faster remains roughly constant as your speed increases. For example, it takes the same increase in effort to overcome rolling resistance when you go from 8 to 9 mph as it does when you go from 18 to 19 mph. In other words, no matter what your current speed is, the same increase in effort will be enough to overcome the increase in rolling resistance when you go 1 mph faster.

Now take a look at the shape of the function for air resistance. It curves sharply up; it’s not a straight line. This is not good news for the cyclist. It means that equal increases in speed (for example, an increase of 1 mph) demand an ever-larger amount of effort the faster you go. For example, it takes more effort to overcome air resistance when you go from 8 to 9 mph than it does to overcome air resistance when you go from 7 to 8 mph and it takes a lot more effort to go from 18 to 19 mph than it does to go from 8 to 9 mph. In other words, overcoming air resistance gets harder and harder the faster you go. When you get to the speed where the pros ride overcoming air resistance takes enormous increases in effort to produce tiny increases in speed.

Overcoming air resistance gets harder and harder the faster you go. How quickly does the increase in effort needed to overcome air resistance ramp up?

watts and wind resistence_ key pointsLooking at the effort needed to overcome air resistance as a proportion of the total effort expended can answer this question. At approximately 12 kph (7.5 mph) overcoming air resistance is taking about half of your effort with rolling and drive resistance accounting for the other half. As you go faster, overcoming air resistance demands a larger and larger proportion of your total effort. By the time you get to 25 kph (15.5 mph) approximately 70% of the effort you are putting out is being used to overcome air resistance. When you get to 20 mph (about 32 kph) roughly 85% of your effort is devoted to overcoming air resistance. And it just gets harder after that. According to the UCI (the governing body for professional cycling) the typical average speed for a flat stage in the Tour de France is about 47 kph (29.2 mph). The power demands for overcoming air and total resistance are off the chart for our graph but from the information on the graph we can calculate that over 90% of the effort needed to maintain this speed is used to overcome air resistance.

What would riding a bike be like if you didn’t have to overcome air resistance? Reading from the graph, it takes about 100 watts of power to overcome the combination of rolling, drive and air resistance when you’re going 25 kph (15.5 mph). If you take air resistance out of the equation and imagine the linear functions for rolling and drive resistance extending beyond the 50 kph boundary on the right side of the graph and continuing to increase at roughly the same rate, that same 100 watts of power would be sufficient to move you forward (on a very rough estimate) at a speed of about 125 kph (77.7 mph).

Okay, air resistance is the problem. What’s the solution? There are many ways to reduce air resistance such as riding in a full aero position on the bike which is both difficult and uncomfortable, spending tens of thousands of dollars on a high tech aerodynamic bike and a sleek aerodynamic kit, and some simple and much less demanding riding techniques that can provide small but significant benefits. We’ll examine some of these simple techniques in Aerodynamics Part 2.

Eyeing the Line

corneringWhen you hear cyclists talking about their line they’re often talking about cornering. The line they’re talking about is the best path to ride when going through the corner at speed. While this is a good skill to practice and learn, there are many other situations where paying attention to your line is important. This is especially true for cyclists who are not experienced racers, who may not have given much thought to their line, or who may not be aware of how keeping your eye on the line can make some dangerous situations much safer.

First of all, what are we talking about when we say “eyeing the line’? Your line is simply the path you intend your bike to follow on the road ahead. Eyeing the line means keeping your eyes on this path.

Wait . . what? This is a post telling riders to look where they’re going? Duh! I know it sounds obvious but, if you’re like me, you’re going to be surprised how often you don’t really do it very well once you start paying attention to it.

If you’re eyeing your line the right way, how far ahead of your bike should you be looking? That’s going to depend on how fast you’re going. You should be eyeing your line far enough ahead that you see and have ample time to react to any obstacles that might lie in the road. Usually somewhere between 2 to 5 bike lengths ahead is about right. If you find yourself surprised by road debris that you come upon too fast or you hit potholes that you see too late to avoid, you’ve been staring at a point on the road that is too close to the front of your bike.

So far, all of this is pretty straightforward and is mostly a matter of common sense. Eyeing the line can really make a big difference, however, when you have to negotiate obstacles in your path. This is where keeping your eye on the line can make your ride much safer.

potholesRoad debris like sticks, stones, gravel, and glass and road conditions like potholes, narrow or absent shoulders, drop offs at the edge of the road, and narrow lanes between vehicles or between vehicles and the curb are all potentially dangerous obstacles on a ride. Eyeing the line is the most effective technique cyclists have for getting past these obstacles safely.

The technique is simple enough. See the problem, plan your line past the problem, and keep your eye on the line ahead as you ride past the problem.

Sounds simple but to carry it you have to overcome a natural tendency that can get you into trouble. When approaching an obstacle, people tend to either keep their eyes fixed on the obstacle or keep alternating between looking at their path and looking at the obstacle. You see a pothole and you keep looking at the pothole until you’ve gone past it successfully. You have to ride a narrow lane between vehicles or between vehicles and the curb (see the picture below), one of the vehicles is a van or truck with a rear-view mirror that’s at the same height as your head or shoulder, and you keep looking at the mirror until you get past it.

Space between carsThis is a problem because people normally move in the direction their eyes are looking. When you are on the bike, you will naturally steer in the direction you are looking. This is the reason why many riders tend to drift to the left or right when they look over their left or right shoulder to see what’s behind them.

When you’re on the bike and you approach an obstacle and keep looking at it, you have a tendency to steer your bike right at the obstacle rather than around it. If you look back and forth between your line and the obstacle, you tend to waver back and forth on your bike between riding your line and riding at the obstacle. Sometimes you steer toward the obstacle when you look at it and then overcompensate by turning too far in the opposite direction when you realize you’re heading right at the obstacle.

When any of these problems occur you may also have a tendency to slow down. Now you can find yourself in a situation where you’re veering toward the obstacle, veering away from it, your line is lost, and you’re riding so slowly it’s hard keep the bike balanced. Your bike wavers, the obstacle looms, your heart rate goes up, and you either wobble around the obstacle or have to set your foot on the ground and push past the problem. No fun.

cornerFortunately, it’s easy to solve this problem. You have a lifetime of experience moving through the world around you and this experience has made you an expert at seeing the line that will enable you to safely negotiate obstacles in your path. If you are eyeing the line at the right distance in front of your bike, you will automatically pick out a line that allows you to ride around an obstacle in your path. Trust yourself. See the line, evaluate it, trust in your ability to see a good line, and ride toward the obstacle with your eyes on the line ahead. Give a quick flick of your eyes to the obstacle as you are about to draw even with it to make sure it’s where you think it is and then snap your eyes back to your line ahead. Don’t let your eyes stray back to the obstacle for any length of time.

The first couple of times you do this you’re likely to have an overwhelming desire to look at the obstacle as you approach it in order to make sure you’re not going to hit it. However, after doing it successfully a few times you will develop trust in yourself to ride past obstacles while eyeing the line and not the obstacle. It’s fairly easy to do, it doesn’t take long to master, and it is a very useful skill to pick up. Once this approach to obstacles has become a habit, you can begin to work on the more difficult skill of looking at something without steering toward it.

Here’s another situation where the same problem occurs. Think about the difficulty new drivers have trying to keep the car moving in a smooth, straight line down the road. They tend to veer back and forth threatening to crash into whatever happens to be on either side of the road.

Eye-tracking studies with new drivers show a fairly consistent pattern. Naïve drivers tend to focus their eyes at a point on the road that is too close to the front of the car and when they notice an obstacle like a vehicle parked on the side of the road, they spend too long looking at it. The result is that they don’t see obstacles until they are close to them, they steer toward the obstacle, overcompensate when turning back toward the center of the road, see the other side of the road as a new obstacle, steer toward it, and weave back and forth down the street. The movement pattern is very similar for cyclists who are not eyeing the line.

Cell Phone BanFinally, another situation where failing to eye the line can have a large impact on cyclists. Eye tracking studies using high-fidelity driving simulators have also been done with experienced drivers talking on cell phones. In almost every case the drivers reported that their driving performance had not been negatively affected while they were talking on the phone. The eye-tracking data said otherwise. When experienced drivers talk on cell phones they revert to driving like naïve drivers. They tend to focus their eyes too close to the front of the car and tend to spend too long looking at obstacles when they see them. In other words, they stop eyeing the line properly. They also take longer to notice obstacles, are slower to react to them, and are more likely to hit them.

Be aware when you’re on the bike. If you see some clown talking on a cell phone while driving, be hyper-aware. They’re a lot less competent and a lot more dangerous than they think they are and you’re the obstacle.