What is Bonking?

Page may contain affiliate links. Please see terms for details.

Cuchilo

Prize winning member X2
Location
London
Never bonked while cycling but its happened at work a few times . It hits me quick with the shakes and i know i need to go and get a mars bar and a can of coke right away . 2 things i would never buy . You will know it if you get it as it isn't a feeling its your body shutting down and its happening right now :eek:
 
OP
OP
EnPassant

EnPassant

Remember Remember some date in November Member
Location
Gloucester
I'm 6'4" ( if I stand straight, ignoring my knackered knees and back). I weigh 85kg (13.5 stone ish) according to the BMI index I am near obese.
Er, not on any calculator I used. I find the bupa* one the quickest, but they all do the same sum. That puts your BMI at 23 which is normal (25+ for overweight, and 30 for obese), My 93kg and 1.78 which is about 14stone 7 and 5'10" was a bmi of 29.

*not making any pro's or cons for private healthcare btw, just the online calculator, the nhs one asks for age and doesn't use it for anything meaningful that I can see, so cba to enter it.
 

lutonloony

Über Member
Location
torbay
Er, not on any calculator I used. I find the bupa* one the quickest, but they all do the same sum. That puts your BMI at 23 which is normal (25+ for overweight, and 30 for obese), My 93kg and 1.78 which is about 14stone 7 and 5'10" was a bmi of 29.

*not making any pro's or cons for private healthcare btw, just the online calculator, the nhs one asks for age and doesn't use it for anything meaningful that I can see, so cba to enter it.
Just from a chart I saw at hospital . More than likely I got confused with my metric/imperial crossover conversion( must be said that life in general confuses me)
 
OP
OP
EnPassant

EnPassant

Remember Remember some date in November Member
Location
Gloucester
No, I'm not criticising you - I had the same question a couple of years ago. It's just a frequent question we don't have a sticky for.
Fear not, I never considered that you were. Text only is a terrible medium for conveying what one means particularly when there is a subtext to the words used. I don't really like littering my posts with emoticons to obviate it either, they have become so overused they end up nearly meaningless in a lot of instances.
I appreciate the input.
 

johnnyb47

Guru
Location
Wales
I think I suffered from this many years ago in my younger days. It was on a 30 mile ride out and the last leg of the out bound journey was from Llangollen to the top of the Horse Shoe Pass. I did the whole ride without a stop and when I reached the summit and got off my bike at the Ponderosa cafe my legs virtually turned to jelly and I went light headed. I can remember having an insatiable craving for a drink of hot chocolate and a bar of chocolate. After sitting for around 30 minutes I felt well enough to head back but I took it a lot slower as I wasn't still 100℅. If I tried that nowadays I think it would kill me off lol :-)
 

boydj

Legendary Member
Location
Paisley
Tin Pot has described it quite well. It's what marathon runners describe as 'hitting the wall'. The only time it happened to me in a marathon it felt like lead weights had suddenly been attached to my shoes.

You get most of your energy from the glycogen stored in your muscles and other places (e.g. liver). You also burn fat & protein to supplement the glycogen. When the glycogen runs out, you 'bonk'. With highly trained endurance athletes, the 'bonk' is a gradual process as their fat burning processes are switched on earlier and are more efficient. For us lesser mortals, the bonk can come on very quickly and it's not a good place to be.
 
It's not always obvious until you find at the end you're struggling to get food down. I've been there twice. The 1st time was fairly bad but relatively easily sorted. The second time I almost ended up in an ambulance apparently. Eventually they got some sugar down my neck and I picked up. But there was an 80 mile taxi ride home the following day.
 
No, I'm not criticising you - I had the same question a couple of years ago. It's just a frequent question we don't have a sticky for.

I also "wasted" a year gaining weight because I didn't understand metabolism or nutrition.

When you wake up you have depleted the readily available sources in your muscles. If you don't eat, you don't replenish them. As you start to exercise your body tries to metabolise fats and proteins to make the shortfall, problem is that it can't metabolise as fast as your burning it. No problem if it's a thirty minute run or an hour easy ride. But 90 mins into a hilly ride and you've got no glycogen and your muscles are running on empty, your body is rightly saying "stop have break, have a kitkat", your mind is wrongly saying "but I'll get fat!".

If you're a hippie, take a banana or God help us some fig-based weirdness, if you're training for TDF get yourself gels and epo*. Eat a mouthful of something every 20-30mins if you're putting in a decent session over 90 mins. You won't believe the difference it makes if you've never done it.

And don't drink like you're in the fecking Sahara** either.

*Joking. Sort of.
** Unless you are. Surrey doesn't count.
Hmm. The ride I bonked on (well, more at the end rather than during) we were stopping for food and drink pretty regularly. It wasn't a refuelling issue. It was too far basically.
 

nickyboy

Norven Mankey
I've been dog tired on my bike plenty of times but only suffered the bonk once. It's completely different and until you suffer it, it's hard to explain

It's an unravelling of the mental faculties. It's the overwhelming desire just to get off the bike and lie down

It happened to me on a hilly audax after I'd only been cycling a few months. Just failed to eat properly during the ride and I began to lose the ability to recognise where I was on the route. Kept having to stop and check and recheck the route. I finally made it to the finish but had to call home to get picked up (I couldn't face getting back on the bike). The final ignominy was being unable to figure out how to get the wheels off the bike to put it in the boot. My wife had to do it for me and she doesn't even ride a bike
 

Donger

Convoi Exceptionnel
Location
Quedgeley, Glos.
[Tried to post just before 20:30 when the site was suspended. Here we go again with another attempt, though much of what I had to say has already been said in the meantime]

Sounds like your numbness and heavy legs are just your body telling you to dismount for a short while and refuel. Don't take too long over the breaks, though, or you risk "cafe legs" for the next few miles. Regular energy drinks and short stops to stretch, flex my back and move around off the bike do the trick for me. I never go more than 20-25 miles without a short break for a stretch and a re-fuellling when doing longer rides. Most of the audaxes I have done have included control points every 20 miles or so, with refreshments available, suggesting this is the norm.

I have only ever seen anyone "bonk" (in the cycling sense) once. His head started rolling from side to side and he became unresponsive, looking like he was about to drop off the bike. When we stopped to look after him he was like a rag doll and it was actually quite a distressing sight, but a few minutes off the bike, a large handful of jelly babies and some patient encouragement from @Frazzle and me had the desired effect and got him home. Didn't see him on a bike again for a good 6 months after that, which tells you how horrible he found it. I would doubt whether you have actually experienced the phenomenon yet, Steve, and I hope you never do.
 

DaveReading

Don't suffer fools gladly (must try harder!)
Location
Reading, obvs
Tin Pot has described it quite well. It's what marathon runners describe as 'hitting the wall'. The only time it happened to me in a marathon it felt like lead weights had suddenly been attached to my shoes.

That's my understanding too. With marathons, you can delay or even prevent the onset of the wall with sufficient training - on the first one I ran, the last 6 miles were hell, but the second one was a breeze, not because I was fuelled differently but because I had a lot more miles in my legs.

I've never experienced the bonk on the bike, but I assume the same considerations apply there.
 
OP
OP
EnPassant

EnPassant

Remember Remember some date in November Member
Location
Gloucester
[Tried to post just before 20:30 when the site was suspended. Here we go again with another attempt, though much of what I had to say has already been said in the meantime]

Sounds like your numbness and heavy legs are just your body telling you to dismount for a short while and refuel. Don't take too long over the breaks, though, or you risk "cafe legs" for the next few miles. Regular energy drinks and short stops to stretch, flex my back and move around off the bike do the trick for me. I never go more than 20-25 miles without a short break for a stretch and a re-fuellling when doing longer rides. Most of the audaxes I have done have included control points every 20 miles or so, with refreshments available, suggesting this is the norm.

I have only ever seen anyone "bonk" (in the cycling sense) once. His head started rolling from side to side and he became unresponsive, looking like he was about to drop off the bike. When we stopped to look after him he was like a rag doll and it was actually quite a distressing sight, but a few minutes off the bike, a large handful of jelly babies and some patient encouragement from @Frazzle and me had the desired effect and got him home. Didn't see him on a bike again for a good 6 months after that, which tells you how horrible he found it. I would doubt whether you have actually experienced the phenomenon yet, Steve, and I hope you never do.
Absolutely Andy. I am simply too inexperienced to know for sure, certainly compared to many here. Such references as I have seen to 'the bonk' thus far may have been slightly Guilding the Lily as it were. I now know better. I will practice some more and forgo a tiny bit of my drive to become 'stick man' on those occasions where I'm going to do >30 miles.

Practice makes perfect and I'm sure I'll get the hang of it. In honesty the 44 miles I did was in fact partly because I wanted to try again after a similar feeling at the end of the club ride and I wanted to make sure I wouldn't mess up when I go on the next one. The last 10 miles of that were quite hard, but perhaps ameliorated somewhat by the cake and coffee you bought me :smile: (my shout next time). This time I didn't eat at all, next time I will. I certainly do not want have the full experience, it sounds awful.
 
Top Bottom