Why most amateurs underfuel
The two biggest fuelling mistakes amateur cyclists make are (a) starting too late and (b) stopping at whatever feels comfortable rather than what the ride actually demands. Both are fixable with a structured approach.
Your body stores roughly 400-500g of glycogen — enough for 90 to 120 minutes of moderate riding before performance drops. Above threshold, the clock runs faster. Once glycogen depletes, sustainable intensity falls 20-40% as the body switches to slower fat oxidation. This is the classic bonk — and it's entirely preventable with the right fuelling protocol.
The solution isn't eating more of whatever's in your jersey pocket. It's a structured ladder of carbohydrate intake calibrated to ride duration and built on a gut that can actually absorb what you're eating.
The carbs-per-hour ladder
Start at the rung that matches your ride and work up over weeks, not hours.
Under 60 minutes
No in-ride fuel needed. Your glycogen stores easily cover this duration at any intensity.
60-90 minutes, moderate intensity
30-45g of carbs per hour. One gel or a small handful of dates per hour. Optional — most riders don't need it.
90 minutes to 3 hours, moderate-to-hard intensity
60-90g of carbs per hour. This is where fuelling becomes non-optional. Under-fuelling here is the classic 2-hour bonk that wrecks Saturday rides.
3+ hours or race efforts
90-120g of carbs per hour with trained gut capacity. This is pro-level fuelling. Most amateurs don't need it — but gran fondo finishers, ultra riders, and racers targeting sustained high intensity benefit significantly.
The 60g glucose absorption ceiling — and how pros beat it
Single-source glucose absorption caps around 60g per hour. Your small intestine pulls glucose through the SGLT1 transporter, and SGLT1 saturates at that rate. Eating more pure glucose than 60g/hour doesn't help — it just sits in the gut causing bloating, cramping, and GI distress.
The workaround transformed modern cycling nutrition: fructose uses a completely separate transporter (GLUT5). A 2:1 glucose-to-fructose ratio opens two parallel absorption pathways and allows total intakes of 90g, 110g, even 120g per hour without the gut bottleneck.
This is why every serious sports drink and gel launched in the last decade advertises a "2:1 glucose-fructose" or "multi-transportable carbohydrate" formulation. It's not marketing — it's the physiological reason modern pro fuelling works.
Gut training: the step most amateurs skip
Reading about 120g per hour makes people order a case of high-carb gels and try them on their Saturday ride. The result: GI disaster, abandoned ride, and the belief that high-carb fuelling doesn't work for them.
The gut is trainable. Like muscle, it adapts to what you progressively demand of it — and without that adaptation, the absorption and enzymatic capacity simply isn't there.
Gut training protocol:
- Pick a starting carb target (e.g. 60g/hour).
- Consume exactly that target on every long ride for 2-3 weeks — including easy rides.
- Once that feels routine (no bloating, no nausea, no early bathroom stops), step up 15-30g/hour.
- Repeat at each level until you reach your target intake.
Expect 8-12 weeks to go from untrained to 90g/hour comfort. 120g/hour takes longer and not every rider needs to get there.
What to actually eat
The label doesn't matter — total hourly carbs, transporter distribution, and personal tolerance do.
Gels: 20-30g of carbs per gel, typically in a 2:1 glucose-fructose blend. Easy to measure, portable, fast. Some riders tolerate three gels per hour; others get sick at two. Test in training.
Drink mix: 40-90g of carbs per bottle depending on brand and concentration. Useful because fluid and carbs come together, and the dilution reduces GI distress. Maurten, SIS Beta Fuel, and Precision Hydration all offer high-carb formulas.
Real food: bananas (~25g each), rice cakes (homemade, 30-40g each), dates, fig rolls. Best early in rides and at moderate intensity. Becomes harder to digest above threshold.
Bars: 25-40g of carbs each. Slower to chew and digest than gels but a useful middle ground for long rides at endurance intensity.
Most pros and experienced age-groupers cycle through all four during a long ride — real food first 90 minutes, drink mix throughout, gels from hour two, bars during steady sections.
Practical session-by-session fuelling
The 2-hour Saturday ride
60g/hour from minute 30. One gel at 30 min, bottle with 40g carbs, one gel at 75 min. You finish strong instead of hanging on.
The 4-hour long ride
80g/hour from minute 30. Real food first 90 min (banana, rice cake), drink mix throughout (60g/bottle), gels from hour two. Budget 320g total.
The sportive or fondo (5-7 hours)
100-120g/hour from minute 30. Mix of gels, drink mix, bars, and any feed-station food you can trust. Budget 550-840g total. Train this for 6-8 weeks before the event.
The 90-minute hard session
No fuel needed if glycogen is topped off and the session is intervals. If it's a race-pace tempo block, 30-45g/hour after minute 30 reduces central fatigue.
The recovery ride
No fuel. The session is short enough and easy enough that stored glycogen covers it.
Plan your ride fuelling
The in-ride fuelling calculator takes your ride duration, intensity, body weight, and climate and returns exact carbs-per-hour, fluid, and sodium targets. It's calibrated against the same physiological targets coaches use with elite athletes — the numbers scale down appropriately for amateur load and body size.
Free tool: plan your fuelling.
What to do next
- Pick your target. If you've never tracked carbs per hour, start at 60g. If you've fuelled lightly but had GI issues, start at 45g and retrain from there. If you've fuelled consistently at 60-70g, step up to 80-90g with a 2-3 week gut training block.
- Write it down. Weigh what you put in your jersey pocket. Count the grams. Assumptions are where fuelling goes wrong.
- Fuel every long ride — including easy ones. Gut training isn't a hard-session skill. It's a skill you build in base rides.
- Review after three rides. If you're finishing rides with fuel left over, you planned too much and won't finish faster. If you ran out in the last hour, next time start eating sooner.
- Consider coaching. The Not Done Yet coaching community builds nutrition timing into every week of training — not just race day. Fuelling is one of the five pillars we coach, because it's the one that produces the fastest, most visible performance changes.
The carbs-per-hour number matters. The gut training behind it matters more. And the structured approach — the ladder, not the leap — is what separates cyclists who fuel like pros from cyclists who try to fuel like pros and end up in trouble.