Why underfueling is so common
Most amateur cyclists have been shaped — by habit, by culture, or by a vague fear of eating "too much" — to undereat on the bike. The prevailing belief is that if you ride under two hours, food is unnecessary. For very easy spinning, that's approximately true. But the moment you're working at a meaningful pace, or extending a ride beyond 90 minutes, you're asking your body to sustain output that stored glycogen alone cannot reliably support. The fade you feel in the final hour of a long ride is almost always a fueling problem, not a fitness problem. Riders rarely accept this, but it's the most common culprit.
Part of the confusion comes from a misreading of the numbers. Your body stores roughly 400–500g of muscle glycogen — somewhere between 1,500 and 2,000 calories of fuel. That sounds generous. It isn't, once you're riding at 65–75% of your maximum power for two and a half hours. The math runs out quickly, and by the time you register that hollow, heavy feeling, you're already several hundred calories behind. Starting to eat reactively is, at that point, largely too late to fix the problem for that ride.
The numbers: how much carbohydrate you actually need
For rides under about 60–75 minutes at moderate intensity, topping up with carbohydrate provides no meaningful performance benefit — your glycogen stores are sufficient. But for anything longer or harder, the evidence is straightforward: 60g of carbohydrate per hour is a floor, not a ceiling. For rides extending beyond two hours, particularly at sweet spot intensity or above, current sports nutrition consensus puts the target at 60–90g per hour. Most serious amateur cyclists are eating roughly half that, which helps explain why so many long rides fall apart in the final third.
What does 90g per hour look like concretely? Two standard 25g energy gels combined with a 500ml bottle of carbohydrate drink gets you close. Or a banana, a small rice cake, and a gel spread across the hour. The specific format matters less than the total quantity, and the total quantity matters more than most riders want to believe. Some professional riders are now experimenting with 100–120g per hour during races, though that level of intake requires years of gut adaptation and doesn't translate straightforwardly to training. For time-crunched amateurs riding 8–12 hours a week, 60–90g per hour is the realistic and evidence-supported target for any ride where performance matters.
Glucose and fructose: why the ratio matters more than the brand
For years, the accepted ceiling on carbohydrate absorption was around 60g per hour. The reasoning was solid: the primary intestinal transporter for glucose, SGLT1, saturates at approximately 1g per minute. Exceed that rate and the glucose doesn't get absorbed — it stays in the gut, draws in water, and causes the kind of discomfort that ends rides early. That limit held in the research for a long time. Then came work on multiple transportable carbohydrates, and the ceiling moved.
Fructose uses a completely different transporter, GLUT5, which operates independently of the glucose pathway. By combining glucose (or maltodextrin) with fructose in roughly a 2:1 ratio, you run two absorption channels simultaneously. Research confirmed what the theory predicted: mixed glucose-fructose formulations allowed oxidation rates of up to 90g per hour without meaningful gastrointestinal distress, and showed performance improvements in rides lasting over two hours compared to glucose alone. This isn't a marketing claim — it was demonstrated in exercise physiology labs with direct measurement of what the muscles were actually burning.
In practice, this means not all carbohydrate products are equivalent. A gel or drink relying purely on maltodextrin tops out at roughly 60g per hour of usable fuel. Products that blend maltodextrin or glucose with fructose — or that use sucrose, which is half fructose — can sustain higher delivery rates. It's worth checking the label. If fructose or sucrose appears as a significant ingredient, you're formulated for higher-rate fueling. If it's maltodextrin only, you're capped at 60g regardless of how much you consume.
Gut training: the step most riders skip entirely
The single most common mistake when cyclists try to increase their on-bike carbohydrate intake: they attempt 80g per hour during a target race after spending months eating 30g per hour in training. The result is predictable — nausea, bloating, and a very difficult final two hours. Your gut is not simply a passive tube. Its capacity to absorb carbohydrate is a trainable physiological parameter, and like any other fitness adaptation, it requires progressive overload over weeks, not a sudden jump on race day.
Research has shown that cyclists who consistently consumed high carbohydrate intake during training rides increased their exogenous carbohydrate oxidation rates measurably over just a few weeks. The adaptations involve increased density of intestinal transporters and improved gastric emptying rates — real structural changes, not just tolerance. Three weeks of deliberate, progressive fueling practice is typically enough to begin meaningful adaptation. The approach is methodical: start consuming carbohydrates on every training ride over 75 minutes, beginning at 40–50g per hour, and increase gradually by 10g per week towards your target intake. Let training rides absorb the discomfort that comes with learning your gut's limits, rather than discovering them mid-race.
If you want to build fueling practice into a structured training plan — so that carbohydrate adaptation happens alongside fitness development rather than as an afterthought — LeCoach can structure that progression for you. Most training plans treat nutrition as separate from the actual sessions; the better approach is to treat fueling practice as part of the training stimulus itself.
Practical fueling: real food, gels, and timing
The debate over real food versus gels tends to generate more heat than it deserves. Gels and purpose-made carbohydrate drinks have clear advantages for hard efforts: they're precisely calibrated, require no chewing, and can be consumed without interrupting power output. Real food — rice cakes, bananas, dates, boiled potatoes — works well at lower intensities, particularly during the early hours of a long endurance ride when the pace allows time to actually eat. Many professional riders use a pragmatic combination: real food in the first two-thirds of a long ride, switching to gels and liquids in the final hour when intensity rises and digestion slows. That approach makes physiological sense and is worth adopting in your own training.
Timing is the underrated variable. Spreading intake evenly across the ride matters more than most riders realize — a consistent 15 to 20 minute feeding cadence outperforms reactive eating by a significant margin. Consuming all your carbohydrates in the first 45 minutes and then coasting on fumes for the second half is a pattern that's far more common than it should be. By the time you register hunger on a hard ride, you're already in deficit, and catching up is physiologically slow. Treat fueling like pacing: proactive, scheduled, and based on time rather than how you happen to feel in any given moment.
It's also worth noting that the carbohydrate demands of different training sessions vary significantly. A two-hour endurance ride at zone 2 has very different fueling requirements than a session built around sweet spot intervals. If you're not sure how to match fuel to the type of training you're doing, it's worth reading about sweet spot training and what it actually demands — particularly the sustained glycogen cost of riding just below threshold for extended periods.
Sources: Viribay et al. (2025), A Review of Carbohydrate Supplementation Approaches for Elite Long-Distance Endurance — PMC; Podlogar & Wallis (2025), High-Carbohydrate Fueling in the Professional Peloton — Sports Medicine