What is Bonking?

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EnPassant

Remember Remember some date in November Member
Location
Gloucester
With @Fnaar taking a short break, I might get away with asking this seriously.

I think I understand the principle, it's where your body runs out of fuel. However I'm having a bit more difficulty understanding in practice.

So, with a bit of background to start:-
I am trying to lose weight (see weight watchers thread), I started the year at 93kg and am now 75kg. So not actually overweight at all any more (@1.78m), though I'm still not happy that I'm the lean mean machine I want to be, another 5 to 10kg is needed.
As such, I fit the restricted calorie intake around a regime I find the easiest. This means no breakfast because I never wake up hungry. Thus when I go on my daytime ride it's often having not eaten for the better part of probably 12-16 hours. Unsustainable for some I know, but I prefer it that way, because if I eat in the morning when not particularly hungry, I'm still just as hungry by 5 or 6 o'clock as if I hadn't. With a daily calorie limit, it's simpler and easier not to eat in the morning. It causes me no problems on rides up to about 30 miles (and maybe not at all but see following)

Now to the bonk if that's what it is:-
I have also increased my distances over the year and from a start point of about 5 miles a day, I now do 15 to 20 most days with the odd day off. Some of this is just pootling and shopping, and some a bit more vigorous but not racing speed, say 15mph average roughly, maybe 20mph on the flat. None of this causes me an issue. However:-
A couple of times recently I have done 40 miles or a bit more, and here is where I hit some kind of a wall at around 35-40 miles, it's hard to explain exactly and could simply be that I need more fitness/stamina and practice at extended distance. The symptoms are 1. A general feeling of tiredness 2. legs feeling sort of lactated as if I'd just done a climb but I haven't and they won't recover after a few minutes as they would from a climb 3. The numbness in my rear and to some degree hands and feet that I get from road buzz anyway becomes an order of magnitude worse at about this distance.
The long and short of it is I enjoy the ride up to about the 30-35 mile mark, but it becomes a struggle beyond that and all I really want to do is stop.

I could try eating beforehand or during the ride and see if that fixes it, but don't want to on a regular basis until I get closer to my ideal weight, I'll actually be perfectly happy to keep sub 30 miles until then. In any event I'd genuinely like to know other peoples views on what bonking actually is.

TLDR: What are the precise symptoms of a cycling 'bonk'? How can it be differentiated from say simply needing more fitness/practice? What is your personal experience of them? What measures have you taken to avoid them? Did those measures work?

Thanks folks.
 

Drago

Legendary Member
The exercise induced wobliness is 'the bonk'.

"Bonking" is what ill be doing with Carol Vorderman if I ever get the chance.
 

winjim

Straddle the line, discord and rhyme
Nausea, vomiting, dizziness, weakness, incoherence, an absolute inability to function until you get some sugar back in your body. It's hypoglycaemia, not just being a bit tired out. If it's happened to you, then you will know about it, and you will never want it to happen again.


Your legs are lactating?
 

Vapin' Joe

Formerly known as Smokin Joe
With @Fnaar taking a short break, I might get away with asking this seriously.


TLDR: What are the precise symptoms of a cycling 'bonk'? How can it be differentiated from say simply needing more fitness/practice? What is your personal experience of them? What measures have you taken to avoid them? Did those measures work?

Thanks folks.

If you get the bonk you won't mistake it for anything else, you'll just know. All your energy goes, your legs only turn from memory and you feel completely weak and lifeless. You would also kill for a bar of chocolate and a drink. Horrible feeling, the last time I got it was with twenty miles to go in an audax, Sunday afternoon in rural Essex and not a shop open.
 
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gavroche

Getting old but not past it
Location
North Wales
Your body is like a fuel tank, the more you pedal and the further you travel, the more fuel you use. So, in the morning, you still have fuel from your last night's meal so doing 20 miles or so can be done on your reserve fuel. After that, you need refuelling ( energy) so if you don't eat anything and drink, your body will eventually refuse to work and your legs will give up, hence honking. Some people will last longer than others but not indefinitely. I think you worry too much about your weight and not enough about fuelling up. 75kms for your height is fine by the way.
 
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EnPassant

EnPassant

Remember Remember some date in November Member
Location
Gloucester
Nausea, vomiting, dizziness, weakness, incoherence, an absolute inability to function until you get some sugar back in your body. It's hypoglycaemia, not just being a bit tired out. If it's happened to you, then you will know about it, and you will never want it to happen again.
Ok, not that then, or nowhere near that bad. It's another case of 'man the f up' for me then.

Your legs are lactating?
I may have to reconsider my wording there :laugh:
 
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EnPassant

EnPassant

Remember Remember some date in November Member
Location
Gloucester
The exercise induced wobliness is 'the bonk'.

"Bonking" is what ill be doing with Carol Vorderman if I ever get the chance.
A: Starting to understand that
B: Already understand that

75kms for your height is fine by the way.
Oh, it's good for BMI and so forth, but I've still got too much around my middle, it's a bit of a blunt instrument BMI, I'm not large framed I guess, so there's still a beer bump which I want shot of....

I mostly don't eat in the mornings these days either, apart from when I'm on holiday or on tour that is. I have a cup of tea when I get up, and on days when I'm cycling I have a late-morning coffee stop, with milk in the coffee. I reckon I am carrying enough 'reserves' to see me through a fair few miles without coming to any harm :smile:.
Using the reserves is part of the general idea, I didn't eat for 12 hours beforehand - use what's there you damn body you....
 

Erudin

Veteran
Location
Cornwall
You need to eat and drink on longer/harder rides. I've seen club-mates cramp up, get confused and take wrong turns, have to quit a ride and even crash badly due to not doing so.

I was able to restrict calories and when I was well overweight, but as I lost the weight I found I needed more carbs/sugars in my diet to keep improving.
 
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EnPassant

EnPassant

Remember Remember some date in November Member
Location
Gloucester
Yeah you got me @Tin Pot .
In my defence I didn't really know, I've seen it mentioned but despite a search no complete explanation.
Once I ask and due to the good people hereabouts within seconds I am much clearer about it.
I'm clearly a wimp. mtfu will sort it.
 

iandg

Legendary Member
On the bike I start to go dizzy and light headed, have trouble holding my weight on the bars then the legs go to water.

In the bedroom when I bonk it's a completely different experience.
 
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Tin Pot

Guru
The symptoms are 1. A general feeling of tiredness 2. legs feeling sort of lactated as if I'd just done a climb but I haven't and they won't recover after a few minutes as they would from a climb 3. The numbness in my rear and to some degree hands and feet that I get from road buzz anyway becomes an order of magnitude worse at about this distance.
The long and short of it is I enjoy the ride up to about the 30-35 mile mark, but it becomes a struggle beyond that and all I really want to do is stop.

You are simply not that used to long rides, and exercise over 90 mins you should be fueling. Do it properly and it won't affect your weight loss, because you are burning the fuel as you exercise. Fueling properly also allows you to get the most training benefit from your exercise.

Have you any metrics for your forty milers? And frequency?
 
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