NutritionAnswer

HOW DO YOU AVOID BONKING ON A BIKE RIDE?

By Anthony WalshRoadman CyclingUpdated 10 July 2026

ANSWER

Bonking — the sudden, debilitating loss of energy caused by glycogen depletion — is prevented by eating 60-80g of carbohydrate per hour from the first 30-45 minutes of any ride over 90 minutes. Your muscles and liver store approximately 90-120 minutes of glycogen at moderate intensity. Once those stores are empty, blood glucose crashes and your brain and muscles cannot sustain the effort. The fix is simple: start eating early, eat consistently, and do not wait until you feel hungry. A combination of gels, bars, and a carbohydrate drink delivers the required intake without overloading the stomach.

KEY TAKEAWAYS

Bonking occurs when glycogen stores are depleted — typically after 90-120 minutes of moderate riding.
Eat 60-80g carbohydrate per hour, starting 30-45 minutes into the ride.
A mix of glucose and fructose (2:1 ratio) maximises absorption and reduces stomach distress.
Starting fuelling early is the key — once you bonk, recovery during the ride is very slow.
Pacing conservatively in the first half preserves glycogen and delays depletion.

WHO THIS IS FOR

IS THIS YOU?

The rider who has bonked and never wants to again

You have experienced the wall on a long ride and want to make sure it does not happen again.

The rider preparing for their first long event

You are building up to a sportive or century and want to get your fuelling strategy right before the day.

THE ROADMAN VIEW

Bonking is not a fitness problem — it is a fuelling problem. You ran out of carbohydrate. Your engine is fine; you just forgot to put fuel in the tank. Every single case of bonking I have seen comes down to the same thing: the rider did not eat enough, soon enough.

The rule is ridiculously simple: eat something every 20-30 minutes on any ride over 90 minutes, starting at the 30-45 minute mark. A gel, half a bar, a banana — it does not matter what. Just get 60-80g of carbohydrate in per hour. Your gut will not love you at first, but after a few weeks of practise it adapts and you will barely notice. The alternative is hitting the wall at hour three and crawling home. Your choice.

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

Dr Asker JeukendrupSports nutrition researcher, multiple carbohydrate transport pioneer
Glycogen stores in a well-fed athlete support approximately 90-120 minutes of moderate-to-hard exercise. Carbohydrate ingestion at 60-90g per hour using multiple transportable carbohydrate sources (glucose + fructose in a 2:1 ratio) maximises exogenous fuel delivery and delays glycogen depletion by 30-60 minutes.
Dr James MortonTeam Sky / Ineos nutritionist
The World Tour peloton has moved to very high carbohydrate intake during stages — 90-120g per hour for some riders. For amateurs, 60-80g per hour is the practical target. The critical variable is consistency: eating at regular intervals from early in the ride, not waiting until the final hour.

PRACTICAL APPLICATION

DO THIS WEEK

Start eating at 30-45 minutes
Do not wait until you are hungry. By the time hunger or fatigue arrives, glycogen is already critically low and recovery during the ride is painfully slow. Set a timer on your head unit or watch for 30-minute intervals.
Aim for 60-80g carbohydrate per hour from all sources
Combine gels (20-30g each), bars (30-50g each), and a carbohydrate drink (30-40g per 500ml bottle). Example hourly plan: one gel + sips from a carb drink = 60-70g. Adjust based on intensity — harder efforts require more fuel.
Train your gut in training, not on event day
Your gut absorbs carbohydrate more efficiently when trained to do so. Practise your fuelling strategy on every long ride for at least 4-6 weeks before your target event. Start at 40g per hour and build to 60-80g.
Pace the first half conservatively
Starting too hard burns glycogen faster. Ride the first half of a long event at 10-15% below your target power. This preserves glycogen for the second half, when fatigue and depletion hit hardest.

COMMON MISTAKES

WHAT CYCLISTS GET WRONG

MISTAKEWaiting until you feel hungry or tired to start eating.
FIXHunger is a lagging indicator of glycogen depletion. By the time you feel it, you are already 20-30 minutes behind on fuelling. Eat to a schedule, not to appetite.
MISTAKEOnly drinking water on long rides.
FIXWater replaces fluid but not fuel. On rides over 90 minutes, at least one bottle should contain carbohydrate (30-40g per 500ml) plus electrolytes. This delivers fuel passively through your drinking habit.
MISTAKEGoing hard in the first 30 minutes of a long ride.
FIXA fast start depletes glycogen at a much higher rate. The first 30 minutes should feel almost too easy. Save the effort for the second half, when proper fuelling will carry you through.

FAQ

FREQUENTLY ASKED QUESTIONS

What does bonking feel like?

Sudden, severe fatigue — your legs feel empty, your brain gets foggy, you may feel dizzy or nauseous. Power output drops 30-50% and every pedal stroke requires conscious effort. Some riders describe it as 'the lights going out'.

Can you recover from a bonk during a ride?

Partially, but it takes 20-40 minutes of easy riding while consuming fast-absorbing carbohydrate (gels, sugary drink). You will not return to full power. Prevention is far easier than recovery.

Do fit riders bonk less than unfit riders?

Fit riders are better at oxidising fat, which spares glycogen, so they can ride longer before depletion. But any rider — regardless of fitness — will bonk if they ride long and hard enough without eating. Fuelling is non-negotiable.

Does carb-loading the night before prevent bonking?

It helps by maximising starting glycogen stores, which delays depletion by 15-30 minutes. But it does not replace on-bike fuelling. You must still eat during the ride to cover anything beyond 90-120 minutes.

Is 60g of carbs per hour enough for a hard ride?

For most amateurs at moderate intensity, 60g per hour is sufficient. For hard racing or rides above threshold, 80-90g per hour may be needed. Train your gut at 60g and increase to 80g if you find you are still fading late in hard efforts.