Why On-Bike Nutrition Matters
Your body stores ~2,000 calories of glycogen — enough for 60-90 minutes of hard cycling. After that, you "bonk" (hit the wall). On-bike nutrition extends your energy by delivering carbohydrates your muscles can use in real-time. Get this wrong and no amount of fitness saves you. Track your nutrition timing with a cycling computer.
The Science
Dr. Asker Jeukendrup, the leading sports nutrition researcher, has demonstrated that trained athletes can absorb up to 90g carbs/hour using a 2:1 glucose:fructose ratio. Untrained guts absorb 40-60g. This is a trainable adaptation.
Below 60 minutes: water is sufficient. 60-90 min: water + light carbs. Over 90 min: structured fueling is essential.
Carbohydrate Sources
| Source | Carbs | Speed | Best For |
|---|---|---|---|
| Energy gels | 20-30g per gel | Fastest absorption | Racing, intensity |
| Energy chews | 25-40g per pack | Fast | Steady intake, easier on stomach |
| Bars | 30-45g per bar | Moderate | Long endurance, satisfying |
| Drink mix | 30-60g per bottle | Fast | Hydration + fuel combined |
| Real food | Varies | Slow | Long rides, personal preference |
Hydration Strategy
Under 60 min: Water is fine. 16-24 oz per hour depending on heat.
Over 60 min: Electrolyte drink. Sodium is critical — you lose 500-1500mg/hour through sweat.
Hot conditions: Increase to 28-40 oz/hour. Add extra sodium. Pre-hydrate before the ride.
Timing by Ride Duration
| Duration | Fueling Strategy |
|---|---|
| Under 60 min | Water only. No food needed. |
| 60-90 min | Water + 30g carbs in last 30 min |
| 90 min - 3 hrs | 40-60g carbs/hour from start of hour 1 |
| 3+ hours | 60-90g carbs/hour, mix sources, electrolytes every hour |
Golden rule: Start fueling before you're hungry. By the time you feel it, you're already behind. Eat/drink every 20-30 minutes on rides over 90 min.
Product Types Compared
Gels: Fastest, most portable, can cause stomach issues. Best mid-race.
Chews: Easier to eat incrementally. Better for steady state.
Bars: Most satisfying, slowest absorption. Best early in long rides.
Drink mix: Combines hydration and fuel. Simple logistics.
Real food: Rice cakes, PB&J, bananas. Fine for endurance pace. Test in training first.
Top Picks
Sources & Further Reading
- Sports Nutrition for Endurance Athletes, Asker Jeukendrup PhD, 2025.
- British Journal of Sports Medicine Cycling Nutrition Review, 2024.
- SiS Science in Sport Research, 2025.
- TrainingPeaks Nutrition Guide, 2025.
- Cycling Weekly Fueling Guide, 2025.
