On the Bike: Avoiding the Bonk

On the Bike: Avoiding the Bonk

OH. THE DREADED BONK. IF YOU’VE NEVER HEARD THE TERM, it’s usually uttered by cyclists under their breath when their rides go south. Most don’t like to talk about it too loudly—as if not saying the word will avoid its onset. It is the nemesis of a good, fun ride.

Sound dramatic? Bonking is what happens when your body’s levels of fuel or water (or both) gets too low. What does it feel like? Well, it not only affects your performance—though it can suddenly feel like you’re pedaling through cement while someone has a rope attached to you pulling you backward. Your body will sag, and you’ll feel like you can’t force your legs to move. Worse yet, since your brain also runs on glycogen and needs to be hydrated to process things, you can feel confused, fuzzy-headed, angry, and desperate. Crying, swearing, or lock-jawed silence from your normally chatty friend is not unusual or an exaggeration of symptoms experienced while bonking.

The funny thing about it is that it’s easily avoidable. Dr. Stacy Sims breaks it down for us. “There are two types of ‘bonks.’ One is the dead-leg fatigue that most people perceive as low calories; but really it is dehydration. This is the bonk you do not want to experience, as it takes hours to come back from dehydration. The second type is a true low blood sugar bonk. This is the light-headedness, tunnel-vision type of bonk that can be corrected easily with a bit of food and takes about 10 minutes to come right.”

It really doesn’t take much: Start hydrated and fueled, then eat and drink on the bike. Problem solved. But no matter how many times it’s said, cyclists often have a strange compulsion to be the hero. If you didn’t know, heroes don’t eat, drink, or stop—ever. They have the mentality that if you need sustenance, well, you must be some kind of a wimp. It’s the unspoken code of amateur cyclists. This is why bonking is so very, very common among us mere mortals aspiring to be heroes.

Of course, all the pros—those real heroes—know (and every book you read on nutrition, including this one, will tell you) that without food or water, bonking is inevitable. So the pros live by the code of religious eating and drinking. It is a part of their riding as much as breathing, and it should be for you, too.

Ignore your buddy who brags that he only needs one bottle for a 4-hour ride in 100-degree heat. Smile kindly on your friend who leaves for your all-day pedaling adventure with a single energy bar. Hero is something you earn when they’re on the side of the road, bent over their handlebars unable to go another pedal stroke, and you share your food or water. Because you came prepared, you have some to spare.

Eating vs. Drinking Your Calories 

There are two ways to get calories for fuel on the bike. One is eating, the other is drinking. New studies show that the best way to keep a steady intake of calories and hydration into your system is to keep your drink low in calories (which makes it trickier for your body to absorb the fluid) and, as much as possible, eat real food.

When you’re on the bike, you lose water and salt through sweat, and as that water transfers to your skin, your blood becomes thicker—which makes it harder for the blood to deliver what the muscles need. So to balance that out, you need to get water back into the system. In the meantime, your muscles and skin are battling for bloodflow—your skin to get rid of heat, and your muscles to keep riding. The more hydrated you are, the less severe this battle gets. In the end, if you don’t drink, your skin will always win the battle because being overheated will kill you, so your body will default to taking care of you by sweating. This is one way the dreaded bonk will set in.

Although it may seem like a great idea to get your calories and electrolytes through your drink, the problem is that many sports drinks made to use on the bike are too concentrated and focused on giving you calories, so they actually draw water out of your bloodstream to digest—even if they are in a solution of water. This can cause stomach cramping and bloating, not to mention dehydration.

The solution is to get the majority of your calories from food, and keep your fluids to a source that has some electrolytes but not too many carbs. Another benefit from separating the two is that on hotter days, you’ll need more fluid, but not necessarily more calories. Keeping the two in their own categories lets you regulate each as you need.

Fueling in the Saddle 

Your body already knows how to digest food well, so when someone says, “I can’t eat on the bike!” you know that’s just plain silly. You already eat at least three times a day, right? On the bike, your main priority is to keep a good input of carbs going. On longer rides, throwing in a little fat or protein is good, too. The general guideline for what to eat and when to eat it starts after the first hour of your ride. In other words, if you’re riding only an hour or a little over, you don’t need to eat (but you always need to drink). If you plan on riding over 2 hours, you should start eating 45 minutes to an hour into your ride, and keep eating small amounts every 15 to 20 minutes.

Overall, you need around 30 to 60 grams of carbs an hour, or about 3 to 4 calories per kilogram per hour of food, for a moderate ride. To give you some reference, one medium banana is around 30 grams of carbs and 120 calories. Spread out your eating into 15- to 20-minute intervals over the hour. Remember, your blood is already working to keep your muscles fueled and your body temperature down. If you eat the whole banana at once, it will force more of your blood to concentrate in your digestive system, pulling it away from the more important jobs it needs to do to keep you going.

It’s also harder for your body to digest a large amount of calories at once as opposed to small amounts. The trick to not running out of fuel is to keep eating small amounts of food every 15 to 20 minutes on your ride. Think of how you feel after a big Thanksgiving meal versus a small afternoon snack. When riders claim to not be able to eat on the bike, it’s usually because they’re trying to eat too much at once instead of spacing it out into small snack bites. “But I’m not hungry!” you insist. If you wait until you feel hunger, you’re already in too much of a deficit to catch up—and you’ll be behind for the rest of your ride.

To keep yourself honest, use your bike computer or watch to set a timer to go off every 20 minutes. Do not play the “promises” game, where you know you should grab food from your pocket but are going to wait until “the next intersection,” “the top of the climb,” “when we slow down,” or “at mile forty.” If it’s time to eat, eat. No compromises.

To find foods that work on the bike, look at what your body needs and how much space you have to carry it. Food needs to be able to fit in your pocket, be easily grabbed and manipulated with one hand, and have a high concentration of easily absorbed carbohydrates. Oh, and most importantly, it should be food that tastes good so you’ll want to eat it.

Choosing real, natural food is a good place to start. High-carb foods that transport well on the bike include bananas, nuts, peanut butter and honey sandwiches cut into quarters, or snack bars made with rice or quinoa—which are great if you want to switch from sweet to savory. It helps if it has fat or proteins, but the majority of your calories should be coming from carbohydrates. One thing to be aware of is to not take in too much fresh or dried fruit, or other high-fiber foods. These take more energy to digest, and can cause an upset stomach.

Real food not only tastes great, but it’s also much cheaper than energy bars and gels. These are also good things to have on hand, but it’s best not to count on them for all your calories. Energy bars are very calorie-dense, so it’s easy to eat too many or too much. Gels, goos, and chews are okay if you’re bonking or near the end of a ride that is over 3 or 4 hours—like a century or a bike tour—and you need a little energy but don’t feel like eating more food. But always remember that you need to drink lots of water with them if you want to avoid gut rot and dehydration. A better and more easily digested boost can come from foods you can find at the gas station (like gummy bears or jelly beans) or glucose tablets, which don’t take as much water from your system to digest. These are also great for racing where you’re trying to be as light and compact as possible, and when you may not have time to grab your food.

If you haven’t already practiced, it’s good to get in the habit of being able to reach into your jersey pocket while riding with one hand on your handlebars to grab and eat your food. You don’t want to stop every 15 to 20 minutes to eat. Find a parking lot or quiet street and practice grabbing, opening, and closing your food packaging and putting any leftovers or garbage back into your pocket while on the move. Concentrate on holding your line and not wavering from your position in the road. After a while, you’ll know how much speed you need to hold to smoothly grab a bite as you roll, and eating while you ride will become second nature.

Drinking and Riding

We’ve already talked a lot about how important hydration is and that even on the shortest rides you need to drink. First, get into the good habit of regularly reaching for your water bottle. You need to take in around one to two 16-ounce bottles of fluid an hour, no matter how long you’re on the bike. Like food, it’s hard for your body to take it all in at once, so it’s better spaced out over 10-minute intervals. Drink 3 to 4 ounces at a time—that’s a few big glugs, not sips.

If you don’t feel comfortable reaching down for your water bottle yet, spend a whole afternoon just practicing reaching down for it, taking a drink and returning the bottle to its cage. Sometimes this is harder than it looks, so investing an afternoon that you would be out pedaling to learning this small skill is huge if you’re going to have a good ride without getting dehydrated.

Again, hydrating is something that most nonprofessional cyclists forget to do all the time, so get in the habit by setting an alarm or watching the clock. After working on this regularly over weeks and months, your body will start to feel a little thirsty every 10 minutes without the reminders. If it’s hot out, aim for two bottles of water or an electrolyte drink an hour. No matter what, you cannot catch up if you get dehydrated. In fact, even if you follow this guide to the letter, you’ll still end up a little dehydrated at the end of the ride, as it’s impossible to keep up with what your body will use.

Caffeine: Friend or Foe?

Most of us have some kind of relationship with caffeine. Whether it’s a few cups of coffee to get your morning rolling or a simple cup of green or black tea, it’s a ritual we’d be loath to give up.

Lucky for us, caffeine has been proven to be an excellent performance booster on the bike as well. Beyond making you more alert and focused, it can help you burn carbs a little faster and stimulate the release of fatty acids, which help you save on your glycogen stores while still staying fueled.

It was thought for years that caffeine was to be avoided because it would dehydrate you—especially bad on hot days. Finally, a scientist thought to study it and found that it doesn’t make you sweat or pee any more than any other drink. It does, however, improve your strength, endurance, and perception of how hard you’re pushing—meaning you can go harder with less pain. The benefits last even after your workout is over, as it can also decrease post-ride soreness.

That being said, even if you consider yourself a regular coffee addict, you might want to cut back a little to conserve your boost. If you start your ride stimulated, not only will you make yourself jittery and anxious, but you also won’t be able to get the boost you need at the end of the ride when you may be hurting. Professional and amateur cyclists agree on one thing: In the last quarter of your ride, an icy cola on a hot day or a hot espresso on a cold one can be a game changer, turning your ride from a death march to a dance home. If you don’t have access to a store or café, a caffeinated gel or chew can do the trick—though it’s definitely not as tasty.