Bonking On The Bike- Explaining Different Cycling Limiters

Cyclists may not understand what's the reason behind the slowing down, are they simply tired or something else is happening to them? It could be glycogen depletion, or it could do something with blood glucose levels. In this guide, we explain what bonking and other cycling limiters are and how we can control them!

Who would have thought that even cycling has limiters? What are cycling limiters you ask? Well, the most common limiters are muscular endurance, neuromuscular/speed, and aerobic/endurance. These limiters are fueled by conditions like cramping, or just fatigue, and even bonking.

Bonking is extreme fatigue which happens because your body gets depleted of the needed glycogen stores. This leads to low blood sugar. Now, if this happens there are some symptoms you might notice like nausea, inability to move, and even poor coordination. Let’s discuss bonking in a bit more detail so you can know how to avoid it!

Feeling Tired After Long Cycling
Feeling Tired After Long Cycling

Why Does Bonking Occur?

The big bad question is, Why Does Bonking Occur? A person will bonk when their body’s glycogen stores have been fully depleted. When the carb intake is low, there becomes a problem with the blood glucose production, and that then leads to bonking. This is the main reason why bonking occurs.

When there is not enough blood glucose in the body, there is not enough strength to have intense rides or even day-long rides. The best method to avoid bonking is by taking care of your carb intake. If you feel hungry during a ride, do stop and eat something, even having a sports drink would count. 

What are The Symptoms of Bonking?

The first thing that cyclists can experience is the drastic loss of performance when this happens you will not be able to continue riding. As the energy stores will be depleted, you will not be able to do much and also lose motivation. 

You will still be burning fat but it won’t do you that much good. Not being able to function properly will take a toll on the rider. During a normal bike ride, this might not happen. The chances of it happening are during long rides and steep climbs, where extra efforts are required.

Symptoms Of Bonking
Symptoms Of Bonking

How Deadly is The Brain Bonk?

Some people completely forego how deadly the bonk can be, not just to the cyclist’s body but also to the brain. Your body isn’t the only one that burns glucose for energy production, the brain does too, if you think the effects on the body are intense, just wait till you see what happens with the brain.

In addition to the physical deficiencies, you will also be experiencing mental and emotional problems and they are going to be much more severe. When there is not enough glucose in the brain, you may experience the following symptoms:

  • Blurred Vision
  • Nausea
  • Severe Confusion
  • Migraines
  • Poor Coordination
  • Body Shaking 
  • Light-Headedness

What happens when a  person’s blood glucose drops too low is that the body starts to protect the brain by allocating all the energy to it. This way all the muscles are shut down. However, you will still not feel the physical effects till all the energy is allocated to the brain.

My point here is that the mental effects of bonking are going to be far more deadly than the physical ones. You might even experience hallucinations or something even worse, think of it as consuming too many drugs at once!

The Different Emotionally Charged Stages of Bonking

Bonking is an evil thing that happens to cyclists, we get that, but how severe can it be? People who are still in limbo about this need to know about the stages of bonking. Time to reel you guys in with the details!

Stage 1: Denial Will Be Everywhere

The first stage of bonking is going to be denial, and there will be a lot of denials. If you are in a group while cycling, you will lack the energy and motivation to stay with the group. Your vision will start getting blurry and you will not be able to go in a straight line, and then this thought will occur- “Maybe this is because I am going too hard on myself?”

The energy required to go forward will suddenly vanish and will experience the legs turn. You will then start thinking that this is not just you but everyone will be feeling the same way. 

However, what is going in that your glycogen reserves will be ending and quite rapidly at that? When this happens, your brain ceases to function properly.

Stage 2: There Will Be A Lot of Anger

After denial comes anger, and riders afflicted with bonking will start showing signs of aggression. Aggression doesn’t mean that the riders will start hitting each other, this will be a different kind of anger. The world in front of you will become 25mm wider, and you will start venting at your friends for leaving you alone in this critical time.

Although this will not be the case, your friends will just be ahead of you, having a fun time riding. Even some of the best endurance athletes will suffer at the hands of bonking sometimes, so you best be ready.

The main problem is that you did not eat enough, and you find comfort when you blame your situation on others. You will get angry for not packing enough food, maybe also at others when you guys didn’t have that snack break. It may seem that everyone is trying to ruin your day.

In the end, you will come to know that this anger is just a surge in the adrenaline levels, think of it as an emergency state of the body when the energy is rapidly draining.

Stage 3: You Will Try To Bargain

Till now you must have realized that your glycogen stores are dangerously low, and you need to do something about it and fast. Thoughts start rambling through your brain, maybe if you stop somewhere and have energy jello or a drink, everything will go back to normal.

You are even willing to go further, maybe even try asking some of your “friends” for something to eat. You will pretend to be extra good to get sports nutrition back. At this point, anything must be done to get back the energy.

Your body desperately needs fuel at this point and you will stop at nothing to get it, maybe even sacrificing your dignity will seem a viable solution. You will even hurt your fragile ego to get the food your body so desperately wants.

Stage 4: Depression Starts 

Now things will start getting serious, and you might start having depression. There will be some serious regrets, maybe why you skipped breakfast in the first place. Let me tell you, you could even end up crying on your bike, there will be a lot of tears.

I am not afraid to admit that I have done the same, I have also cried during bonking. At this time, any sign of food, any kind of food will seem like God-Send. There will be a lot of fatigue, this is because your blood sugar will be dropping and even the adrenaline will run out. The endorphins will have left your body by now, as your cycling group did on that last steep climb. 

Stage 5: Accept The Truth

Time to accept the truth now, it is time to accept your defeat against the cycling limitation. You will now just head to any grocery store and get yourself a delicious snack, after all, you need to fill your body with the essential energy.

Hydration needs to be fulfilled too, so it would be advised that you also get something to drink alongside a snack. Make sure that you have enough food before cycling again, freshening up will also be a good idea.

Now that you have gotten all the essentials, your body will start calming down. Your blood sugar will get back to normal, and brain functions will also be normal again. Although be prepared for the next bonk, if you are not careful, it might arrive sooner than you think.

Stages Of Bonking

How to Fix Bonking?

There have been many theories about bonking and its solutions, but here is the definite solution- Eat Properly! Since the problem starts with glycogen reserves being depleted, make sure that they never do. Have a really good meal before going out for cycling, it could be a really good lunch or breakfast.

Keep snacks with you, sports drinks are heavily recommended here. Some people would suggest exercise to add some resistance against bonking but that never works, trust me! At some point, your body will give in to bonking and then you will suffer its wrath!

Read also: What Is Anterior Knee Pain? Cycling Pain Explained!

What Is Fatigue?

When you start having performance issues, fatigue will be the first indicator. You will start feeling fatigued when the body’s glycogen levels are low. Fatigue is the effect of bonking. Although they are related to each other, they are also different, here’s how.

The Difference Between Fatigue and Bonking

You may think that fatigue and bonking are the same but in reality, they are not. Bonking is the actual feeling and fatigue is the message that your body is trying to give you that your condition is worsening. Now, your body will tell you to stop whatever you are doing and rest.

This is a cycling limitation, your brain is trying to slow you down and you must listen to it. 

What is Cramping?

Cramping is going to be the deadliest of the cycling limitations that you will ever face. If you don’t take care of it, then cramping will stop you dead in your tracks and you won’t be able to recover from it soon enough, so let’s discuss what it is.

Cramping will be a sharp pain that will be because of bonking and fatigue, think of it as a burning and raging sensation in your body.


Does bonking burn fat?

Bonking is carb-related. And when your body runs out of carbs, it may shift to burning fat. 

Is bonking good for you?

No, bonking is not good because it can damage your muscles and 

What are the side effects of bonking?

Side effects of bonking include muscle loss, immune suppression, and disruption in training.


Bonking is a real pain and cycling limitation. It will stop the riders dead in their tracks if not taken care of. Bonking, Fatigue, and Cramping all are related but they do have differences of their own. We have discussed what they can do, what are the different stages of bonking, and how you can address them.

Bonking happens from time to time, you just need to be fully prepared for it. I hope that with this guide, you have a good amount of knowledge about bonking and how to counter it. Be sure to have an amazing cycling session next time!

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Should you have any questions or require further clarification on the topic, please feel free to connect with our expert author Rhodes Perry by leaving a comment below. We value your engagement and are here to assist you.

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Rhodes Perry

Rhodes Perry

Rhodes is a writer, social justice advocate, and passionate cyclist. He primarily spends his time in the saddle commuting or riding multi-day, self-supported tours, and volunteers time wrenching at his local bike coop.


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