At 32 degrees Celsius, your fueling plan from March no longer works. Not because you're performing worse, but because your body has other priorities. Blood flows to your skin to cool you down, and therefore not to your stomach and intestines. You burn through your own sugar reserves faster, while you absorb less of what you take in while riding. That is the essence of fueling in the summer. If you want to master the basics first, read the complete guide to energy bars for cyclists. Below, we focus purely on heat.

What heat does to your fueling

Two things at once. One: you burn more carbs. A 2025 systematic review with meta-analysis confirmed that carbohydrate expenditure during prolonged exercise increases in hot conditions, and that dehydration exacerbates this effect. Two: you absorb less of them. A 2026 systematic review on carbohydrates in the heat, based on nine crossover studies, explains why. Heat reduces gastric emptying and intestinal absorption because blood flow to your gut decreases.

More consumption. Less absorption. That is a gap that widens as it gets hotter and the ride lasts longer.

The solution isn't stuffing yourself more. The solution is distribution: smaller portions, more often, with sufficient fluids, in doses your stomach is already accustomed to. That same review sets the order clearly: start well-fueled, prioritize hydration and sodium, use only amounts you have trained in similar conditions, and be cautious with highly concentrated drinks.

How many carbs per hour at 30 degrees?

The general guideline remains 60 to 90 g of carbs per hour for efforts longer than 75 minutes. In the heat, start at the lower end. 60 to 75 g per hour is a fair starting point. If you go higher, do it because you have trained for it, not because it looks good on paper.

This is how I distribute it in practice:

• Sports drink is the primary source. 500 to 800 ml per hour at 6 to 8% carbs provides 30 to 60 g. This also covers your fluids. In the heat, that counts double.
• 1 to 2 fruit performance bars per hour. 20 g of carbs per 25 g bar. This is your solid component, and you know exactly what is going in.
• Sodium according to your sweat loss. If you sweat heavily and salty, that requires replenishment. It is not optional for long rides in the heat.

Drink plus 1 to 2 bars brings you to 50 to 90 g per hour, depending on how you structure it. Stacking more bars is not the way to go. A bar does not replace your water bottle.

Drink, gel, or bar: what works in the heat?

I’ll be honest here, even if it goes against my own product. Research on 12 trained cyclists compared drink, gel, bar, and a mix, all at 80 g of carbs per hour during an intense race simulation. The bars caused more stomach issues than the gels and the drink, and performance was likely worse with bars than with gels.

That doesn't mean a bar doesn't work. It means the balance must be as described above: drink carries the volume, the bar is the solid component alongside it. At high intensity, keep the solid portion small. During long rides at a controlled pace—exactly where most summer kilometers are spent—you can perfectly consume 1 to 2 bars per hour. Chew. Drink. Keep riding.

What you don't want in the heat is a concentrated bolus without fluids. Swallowing a gel dry at a time when your stomach is already receiving less blood is asking for trouble. More on the trade-off between the two forms can be found in energy bar versus energy gel: when to use what.

Why 2:1 glucose and fructose matters in the heat too

Glucose and fructose pass through your intestinal wall via two separate transport channels. Glucose hits a limit at around 60 g per hour. Fructose uses its own route and counts on top of that. If you combine them in a 2:1 ratio, you get more carbs in without overloading a single channel.

The core study behind this: eight trained cyclists cycled for two hours and then performed a time trial. With glucose plus fructose in a 2:1 ratio, they performed about 8% better than with glucose alone, and 19% better than with water.

In the heat, that gain is not smaller—it’s more important. If your absorption capacity drops, you want every gram that does make it in to be utilized to the maximum. That is why every Eagle fruit performance bar is built on a 2:1 ratio. Not as a marketing figure, but as a design principle.

Cool versus hot, side by side

Fueling plan for three hours in the heat

Concrete. No theory.

• Before the start. Leave well-fueled. You cannot replenish your glycogen during the ride as fast as you burn it. Keep drinking steadily in the last hour before departure.
• Hour 1. Water bottle with sports drink at 6 to 8% carbs, aim for 500 to 750 ml. One fruit performance bar around minute 40. Chew well, drink along with it.
• Hour 2. Empty second bottle. One to two bars, spaced out. Keep drinking on schedule, not based on thirst.
• Hour 3. The same pattern. If it gets really tough, choose liquid carbs over solid ones. Your stomach has a say in this.
• Above 30 degrees. Start easier than planned. Your heat load builds up faster than you think. Fueling does not compensate for overheating.

This scales. One and a half hours is the same plan, just shorter. Five hours is the same plan, just longer, with more sodium. The logic remains: small, familiar, regular, always with fluids.

Five mistakes you pay for in the summer

• Starting too late. If you feel hungry, you are already behind. Catching up takes 20 to 30 minutes that you don't have.
• Too much at once. Three gels in a row because you're behind. Your stomach will settle the score in the twenty minutes that follow.
• Concentrated carbs without fluids. In the heat, the fastest way to feeling full and nauseous. Always drink with it.
• New stuff on a hot day. Test new flavors and new brands in March. Not at 35 degrees.
• Mixing up fluids and fuel. Water alone is not fuel. A bar alone is not hydration. You need both.

If you structurally run into stomach issues on hot days, the problem is more often in the form and dosage than the brand. Why cyclists are trading gels for a clean label fruit energy bar goes into more detail.

Why I choose fruit as a carb source

Fruit provides glucose and fructose naturally, in a ratio your body recognizes. Dried fruit makes this compact without artificial binders, sweeteners, or colorings. Result: 80 g of carbs per 100 g. Clean carbs, 2:1, in a solid form that you can dose.

Every Eagle fruit performance bar weighs 25 g and provides 20 g of carbs. Vegan, gluten-free, lactose-free, 0% artificials. Produced in a certified Belgian production facility (BRCGS Food Safety, ACS). One bar is one known unit. On a hot day, that is exactly what you want: fewer unknowns in your stomach.

The difference from the sugars you find at a gas station is explained in fruit energy bar versus candy. And if you are just looking for something that works on a long summer ride, the ideal energy source for your bike ride can help.

Heat requires discipline, not panic

More consumption, less absorption. That is all you need to remember. Your answer is not more, but smarter distribution. Drink carries. The bar supplements. Fluids and sodium come first. And you don't test anything new on the day it counts.

No gel. No brick. Fuel during exercise. Fuel your flight.

Choose your fuel