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NutritionAnswer

HOW DO I FUEL A 100-MILE BIKE RIDE?

By Anthony WalshRoadman CyclingUpdated

WHO THIS IS FOR

IS THIS YOU?

The sportive rider preparing for their first century

You have the fitness to ride 100 miles but you are unsure how to eat and drink during a ride that long.

The experienced rider who bonks in the final 30 miles

You have done century rides before but consistently fade in the last hour, and you suspect fuelling is the problem.

THE ROADMAN VIEW

The Roadman view

A century ride is a nutrition event as much as a fitness event. Anthony has said this repeatedly: the riders who bonk at mile 70 are almost never unfit for the distance — they are under-fuelled. Your muscles can store roughly 1,600-2,000 kcal of glycogen, which covers about 90 minutes of moderate-to-hard riding. A 100-mile sportive takes 5-7 hours. The maths is simple: if you do not eat on the bike, you will hit empty long before the finish.

Sam Impey has been clear on the numbers from his World Tour work: 60-80g of carbohydrate per hour is the target for efforts over 2.5 hours. That is roughly one gel plus one 500 ml bottle of carb drink per hour, or two gels and water, or a mix of gels, bars, and real food. The critical habit is starting early — take your first gel or bar at 30 minutes, not at 60. By the time you feel hungry or notice your power dropping, you are 30-45 minutes behind on fuelling and it is very difficult to catch up.

The night-before and morning-of meals are equally important. Carb-loading is not about stuffing yourself — it is about choosing a carb-heavy dinner (pasta, rice, potatoes) and a carb-heavy breakfast (porridge, toast, juice) so your glycogen stores are topped up before you clip in. A rider who starts a century with half-full glycogen because they skipped breakfast or ate low-carb the night before has already lost 30-45 minutes of buffer. And one more thing: practise everything. New gels, new drinks, new food — all of it gets tested on training rides. A century is not the place to discover your stomach hates a particular brand of energy chew.

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

  • Dr Sam ImpeyWorld Tour nutritionist

    For rides over 2.5 hours, the target is 60-80g of carbohydrate per hour using a 2:1 glucose-to-fructose ratio for maximum absorption. Starting fuelling in the first 30 minutes and maintaining consistent intake throughout is more important than the exact products used. The riders who fade late are almost always the ones who started fuelling too late.

    Hear it: Why Pros' 120g Carb Rule Fails Amateurs | Roadman Cycling
  • David DunneWorld Tour nutritionist (Israel-Premier Tech)

    Carb-loading the day before and morning of a long event is non-negotiable at the professional level. We aim for 8-10g of carbohydrate per kilogram of body weight across dinner and breakfast. That is the difference between starting with full glycogen and starting at 60-70% — which on a 5-hour ride equates to roughly 30-45 minutes of extra buffer before you hit the wall.

    Hear it: World Tour Nutritionist - “We Got Weight Loss Wrong”

PRACTICAL APPLICATION

DO THIS WEEK

  1. Carb-load the evening before and morning of

    Dinner: a large plate of pasta, rice, or potatoes with a moderate protein source. Target 3-4g carbs per kg body weight at dinner. Breakfast (2-3 hours before start): porridge with honey and banana, or toast with jam and juice. Target 2-3g carbs per kg. A 75 kg rider needs roughly 225-300g of carbs from dinner to start. This is not overeating — it is fuelling.

  2. Build an hourly fuelling schedule and stick to it

    Set a timer on your head unit for every 20 minutes. At each alert, eat or drink something. Per hour: aim for 60-80g carbs (roughly 2-3 gels, or 1 gel + 1 bar, or gels + a 500 ml carb drink). Pre-load your jersey pockets and top tube bag before the start so you never have to think about what to eat — just follow the schedule.

  3. Practise your exact plan on a 4-hour training ride

    Before the century, do at least two long training rides (3-4 hours) using the exact products, quantities, and timing you plan to use on race day. Pay attention to gut comfort, taste fatigue, and whether your energy holds steady. Adjust brands, formats, or timing based on what you learn. Gut tolerance improves with practice — the more you fuel in training, the more your stomach can handle on race day.

COMMON MISTAKES

WHAT CYCLISTS GET WRONG

  • MISTAKEWaiting until you feel hungry to start eating.

    FIXHunger signals lag 30-45 minutes behind actual energy depletion. By the time you feel hungry, your glycogen is already running low and your power will drop within 20-30 minutes. Start eating at 30 minutes and maintain a consistent schedule throughout.

  • MISTAKERelying on feed stations alone.

    FIXFeed stations on sportives are typically every 25-40 miles, which means gaps of 60-90 minutes between food. That is too infrequent for 60-80g/hr fuelling. Carry your own food and treat feed stations as top-ups, not primary fuel sources.

  • MISTAKETrying new nutrition products on race day.

    FIXEvery stomach responds differently to gels, bars, and drinks. A product that works for your riding partner might give you cramps. Test everything in training at race intensity. If it works three times in training, it will work on race day.

FAQ

FREQUENTLY ASKED QUESTIONS

How many gels do I need for a 100-mile ride?
At 60-80g carbs per hour over a 5-6 hour ride, you need roughly 300-480g of total carbohydrate. Most gels contain 20-30g of carbs each, so you need roughly 10-16 gels if gels are your sole fuel source. In practice, mix gels with bars, bananas, and carb drink to avoid flavour fatigue and provide variety.
Should I eat real food or just gels on a century?
A mix works best for most riders. Gels and carb drinks are fastest to absorb and easiest to consume at tempo pace. Real food (rice cakes, sandwiches, bananas, flapjacks) provides variety and is easier on the stomach for some riders. Use gels for the harder sections and real food during easier stretches or at feed stops.
How much water should I drink during a 100-mile ride?
Aim for 500-750 ml per hour in moderate conditions and up to 1,000 ml per hour in heat. Add 500-1,000 mg of sodium per litre through electrolyte tablets or sports drink. Weigh yourself before and after a training ride to estimate your sweat rate — every kilogram lost is roughly one litre of fluid deficit.
What should I eat the morning before a century?
A carb-heavy breakfast 2-3 hours before the start: porridge with honey and banana, toast with jam, a glass of juice, or a bagel with peanut butter. Target 2-3g of carbohydrate per kilogram of body weight. Avoid high-fat and high-fibre foods that sit heavy in the stomach. A 75 kg rider needs roughly 150-225g of carbs at breakfast.
Why do I bonk at mile 70-80 even though I am fit enough?
Almost certainly a fuelling problem, not a fitness problem. If you started eating too late (after the first hour), ate too little per hour (under 40-50g carbs), or did not carb-load the night before, your glycogen stores deplete before the finish. Bonking at 70-80 miles in a 100-mile ride is the classic pattern of under-fuelling.
Can I train my gut to tolerate more carbs per hour?
Yes. Gut tolerance is trainable. Start at 40g carbs per hour in training and increase by 10g per week over 4-6 weeks. Practise during training rides at the intensity you expect on race day. Research shows that athletes who regularly fuel at high rates in training can absorb and tolerate more on race day — the gut adapts just like muscles do.

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