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NutritionDIAGNOSIS

WHY DO I BONK MID-RIDE?

Two hours in, your legs turn to concrete. Power drops 30%. Your brain fogs. The ride goes from manageable to survival in 15 minutes.

THE SHORT ANSWER

Most often, this is because glycogen depletion — 400-500g of stored carbohydrate exhausted without replacement. The fix: plan your fuelling — 60-90g carbs/hour from minute 30 for rides over 90 min.

WHY THIS HAPPENS

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Glycogen depletion — 400-500g of stored carbohydrate exhausted without replacement

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Starting fuelling too late — waiting until hungry means glycogen is critically low

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Under-dosing carbs — 30g/hour when the ride demands 60-90g/hour

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Pre-ride nutrition gap — skipping breakfast or riding fasted without adjusting intensity

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Pacing too hard early — burning glycogen at threshold when the ride demands endurance pace

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Heat and dehydration amplifying glycogen use rate

WHAT TO DO ABOUT IT

1

Plan your fuelling

60-90g carbs/hour from minute 30 for rides over 90 min

2

Read the carbs-per-hour guide

The gut training ladder from 30g to 120g

3

Fix pre-ride nutrition

2-4g carbs per kg body weight 2-3 hours before

4

Learn pacing

Even effort prevents the early glycogen burn

FREE DIAGNOSTIC

Plan your ride fuelling
Or apply for coaching →

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

Uri CarlsonRegistered dietitian nutritionist; fuelling specialist

Carlson ran the comparison directly — under-fuelled, optimally fuelled, and over-fuelled riding — and the under-fuelled sessions consistently produced the lowest power and felt the hardest. The practical lesson is to start fuelling early and keep carbs coming before you feel empty, because by the time you bonk the glycogen is already gone.

Hear it: Under vs Optimal vs Overfueling on the Bike | Roadman Cycling Podcast