A hundred miles is where fuelling stops being optional. On a two-hour ride you can wing it — you've got enough stored carbohydrate to get away with eating badly. On a century, five, six, sometimes seven hours in the saddle, your body simply cannot store enough fuel to finish. You have to top it up as you go, on schedule, whether you feel like it or not.
Get that right and mile 90 feels like mile 30. Get it wrong and you'll meet the wall somewhere around mile 75, legs full of concrete, brain foggy, watching your average speed bleed away. The difference is almost never fitness. It's fuelling.
So here's the whole plan, hour by hour, the way the best endurance nutritionists build it — scaled for a real amateur on a real century.
The one rule that matters: eat before you need to
Your muscles and liver hold enough carbohydrate — glycogen — for roughly 90 minutes to two hours of hard riding. After that, if you haven't been topping up, the tank empties. That's the bonk. And the cruel part is that once you're in it, you can't eat your way out on the bike. Digestion is too slow to repay a debt that big mid-ride.
So the entire strategy is prevention. You eat from the start, steadily, to keep the tank topped up before it ever runs low. Waiting until you feel hungry is already too late — hunger on a long ride is a warning light, not a starting gun. We went deep on the mechanism in what actually happens when you bonk, but the takeaway is simple: fuel early, fuel often, don't wait.
The target number: 60-90 grams of carbohydrate per hour
Everything in modern endurance nutrition orbits this number. For a century, aim for 60-90 grams of carbohydrate per hour.
Where you land in that range depends on you:
- 60g/hour — smaller rider, steady endurance pace, or newer to structured fuelling. Achievable from a single source of carbohydrate (glucose).
- 75g/hour — a solid default for most amateurs riding a century with intent.
- 90g/hour — bigger rider, riding hard, and only if you've trained your gut for it. At this level you need a glucose-fructose mix (roughly 2:1) because your body can only absorb so much of any single sugar at once. Two transport pathways, more total carbs.
To picture it: a typical energy gel is about 22-25g of carbs. A banana is around 25g. A bottle of decent carb drink mix might be 40-60g. So 75g an hour is roughly a gel plus a banana, or a gel plus half a carb bottle. It adds up fast, which is exactly why you have to be deliberate about it.
The hour-by-hour plan
Here's how it lays out across a five-to-six hour century. Adjust the finish to your own pace.
Night before. Nothing exotic — just a normal, slightly carb-heavier dinner. Rice, pasta, potatoes. You're not carb-loading like a marathon runner; you're topping up glycogen. Hydrate well and don't drink alcohol, which wrecks sleep and next-day fuelling.
Breakfast, 2-3 hours before the start. Carbohydrate-rich, low-fibre, a little protein. Porridge with banana and honey. White toast with jam. Rice with a scrambled egg. Aim for around 1-2g of carbs per kilo of bodyweight — for a 75kg rider that's 75-150g. Low fat and low fibre so it clears your stomach in time. Coffee if that's your normal.
15 minutes before rolling out. A small top-up — a banana, or a gel with a swig of water. This tops the liver off right before you start burning.
Hour 1 (miles 0-18). Start eating now, even though you feel fresh and full. This is the discipline that saves your ride. First bite within 30 minutes. Hit your 60-90g target with something easy on the stomach while your gut is still settling — a banana, a rice cake, an early gel. Sip electrolyte drink.
Hours 2-3 (miles 18-55). Peak fuelling window and the easiest hours to nail because your gut is happy and you feel good. Keep hitting 60-90g/hour on a rhythm — set a timer if you're forgetful. Mix real food and drink-mix. Rotate your two bottles: one plain water, one with electrolytes and carbs. This is prime time to bank fuel for the back half.
Hour 4 (miles 55-75). The critical stretch. This is where under-fuelled riders start to fade, and it's a lagging indicator — a fade here means you under-ate an hour or two ago. Keep eating on schedule even if appetite drops. If solid food is getting hard to face, switch toward gels and drink-mix, which go down easier. Do not skip a feed here because you feel okay; feeling okay is the fuel you ate at mile 55 talking.
Hour 5 and beyond (miles 75-100). The finish. Your gut may be tired of eating and real food can feel like a chore. Lean on gels, chews and carb drink now — liquid and semi-liquid carbs when solid food loses its appeal. Keep the target up right to the final 15-20 miles. A caffeinated gel around mile 80 gives a genuine, well-evidenced lift for the run-in. Don't coast home on empty just because the end is in sight.
Hydration and electrolytes
Fuel is only half the job. Aim for roughly 500-750ml of fluid per hour, more in heat, less in cold. Include sodium — it's the electrolyte you lose most of in sweat, and it helps you actually absorb the fluid rather than passing it straight through.
The simple system: two bottles, one plain water and one with electrolytes and carbs, and you rotate. On hot days, add a third source at feed stops and lean harder on the electrolyte side. Drink to thirst as your baseline, and consciously drink more when it's hot — thirst lags behind real fluid loss when you're working hard in the heat. There's a full breakdown in the cycling hydration guide.
Practise it — don't debut it on the day
The single biggest fuelling mistake amateurs make on a century isn't eating too little. It's trying to eat a lot for the first time on the day itself.
Your gut is trainable. Ask it to absorb 80g of carbs an hour when it's only ever handled 40, and it'll rebel exactly when you're mid-ride and can't do anything about it — cramps, bloating, the works. So you practise. On your long training rides in the weeks before, deliberately fuel at your century target. Find out which gels and foods sit well for you, dial in your bottle mix, and let your gut adapt to the volume. By the time the century comes, your fuelling plan should be boring and rehearsed, not an experiment.
The plan on a plate
Strip it back and here's the whole thing:
- Carb-rich, low-fibre breakfast 2-3 hours out. Small top-up before you roll.
- Start eating within 30 minutes and never stop.
- 60-90g of carbohydrate every hour, on a schedule, not on appetite.
- 500-750ml of fluid per hour with sodium; more in the heat.
- Real food early when your gut is fresh; gels and drink-mix late when it isn't.
- Practise all of it on your long rides first.
Nail those six lines and you'll ride the last 20 miles of your century strong instead of surviving them.
If you want a fuelling plan built around your exact ride, your weight and your pace — and a community of riders working through the same events — that's what the Not Done Yet group is for. Members get structured nutrition and training plans and direct access to ask the questions the internet can't answer. It's $195 a month at skool.com/roadmancycling. Now go and eat before you're hungry.