Cycling Nutrition: The Complete On-Bike Fueling Guide

Why On-Bike Fueling Matters

Your body stores approximately 400-500 grams of glycogen—enough fuel for about 90 minutes of moderate cycling. After that, without external fuel, you'll bonk: that devastating wall of fatigue where your legs turn to concrete and your brain shuts down.

On-bike nutrition isn't just about avoiding the bonk, though. Proper fueling maintains power output, delays fatigue, improves focus, and speeds recovery. Research consistently shows that cyclists who fuel adequately outperform those who rely on stored glycogen alone.

The good news: cycling is easier on the stomach than running. The stable position and consistent effort allow for better digestion, meaning you can consume more calories on the bike than on foot. This is an advantage you should exploit.

The Science of Carbohydrate Intake

Not all carbs are absorbed equally. Understanding how your body processes different sugars is key to optimizing fueling.

Single vs. Multiple Transportable Carbohydrates

Glucose (and maltodextrin) are absorbed via one intestinal pathway, limited to about 60g per hour. Fructose uses a separate pathway. By combining both (typically in a 2:1 or 1:0.8 glucose-to-fructose ratio), you can absorb 90-120g of carbs per hour.

Recommended Intake Rates

Fueling by Ride Duration

Under 60 Minutes

For rides under an hour, you don't strictly need on-bike fuel. Your glycogen stores are sufficient. However, if the intensity is high or you haven't eaten recently, a small amount of carbs won't hurt and may help performance.

• Water is usually sufficient
• Optional: 20-30g carbs if fasted or racing hard
• Focus on pre-ride fueling instead

60-90 Minutes

The gray zone where fueling becomes situational. High-intensity efforts and poor pre-ride nutrition warrant on-bike carbs.

• 30-45g carbs per hour
• One gel or small bar
• 500-750ml water with electrolytes

90 Minutes - 3 Hours

Fueling becomes essential. Start early and stay consistent.

• 60-90g carbs per hour
• Start fueling at 30-45 minutes
• Mix of gels, bars, and drink mix
• Set reminders to eat every 20-30 minutes

3+ Hours (Endurance Rides)

Long rides require aggressive fueling. This is where gut training pays dividends.

• 80-120g carbs per hour if tolerated
• Include real food: rice cakes, sandwiches, fruit
• Plan fuel stops or carry ample supplies
• Electrolyte replacement becomes critical

Hydration Strategy

Dehydration impairs performance before you feel thirsty. Even 2% dehydration can reduce power output by 5-10%. Your hydration strategy should be proactive, not reactive.

Fluid Intake Guidelines

Electrolytes: More Than Marketing

Sweat contains sodium, potassium, magnesium, and calcium. Of these, sodium is the most critical to replace—you lose 300-1000mg per hour depending on sweat rate and concentration.

Signs you're losing too much sodium: muscle cramps, bloating (from drinking water that isn't being absorbed), white residue on kit, cravings for salty food. Consider electrolyte tablets or a higher-sodium drink mix.

Fuel Options: Gels, Bars & Real Food

The best fuel is the fuel you'll actually consume. Variety helps prevent flavor fatigue, and different options suit different conditions.

Energy Gels

Pros: Convenient, fast-acting, precise carb counts, easy to consume at intensity

Cons: Expensive, can cause GI issues, flavor fatigue, need water to digest

• Typical serving: 20-30g carbs
• Best for: Racing, high intensity, latter stages of rides
• Look for: Multiple transportable carbs (glucose + fructose)

Energy Bars

Pros: More satisfying, variety of textures, sustained energy

Cons: Harder to eat at high intensity, slower absorption

• Typical serving: 30-45g carbs
• Best for: Lower intensity, early portions of long rides
• Look for: Easy to unwrap, not too sticky or crumbly

Real Food Options

Pros: Cheap, satisfying, natural ingredients, easy on the stomach

Cons: Bulky, less precise carb counts, harder to eat fast

Carbohydrate Drink Mix

Drink mix combines hydration and fueling efficiently. Modern high-carb mixes deliver 80-100g carbs per bottle, reducing the need for solid food.

• Best for: Racing, reducing digestive load
• Combine with plain water bottle for flexibility
• Higher concentrations require gut training

Training Your Gut

Your intestines adapt to carbohydrate intake just like muscles adapt to training. Athletes who regularly practice high-carb fueling can absorb and tolerate more than those who don't.

The Gut Training Protocol

1. Start low: Begin with 40-50g carbs/hour
2. Increase gradually: Add 10g per week
3. Practice consistently: Every long ride is an opportunity
4. Test products: Try race nutrition during training
5. Monitor response: Track what works and what doesn't

GI distress during rides is usually a sign of too much too soon, or using products you haven't tested. Train your gut like you train your legs—progressively and specifically.

Race Day Fueling Strategies

Pre-Race (3-4 hours before)

• Large carb-focused meal: 150-200g carbs
• Examples: oatmeal with banana, toast with jam, rice
• Low fiber, low fat to ease digestion
• Begin hydrating with electrolytes

Final Hour

• Small top-up: energy bar or gel 30 min before
• Sip water with electrolytes
• Avoid anything new or heavy

During the Race

• Start fueling at 20-30 minutes, not when hungry
• Target 90-120g carbs/hour if gut-trained
• Drink to thirst but monitor bottle usage
• Use gels/drinks for high-intensity moments
• Take advantage of calm moments to eat solid food