How to Fuel a Century Ride: A Cyclist's Complete Nutrition Plan for 100 Miles

You've done the training. You've ridden the long weekends. You've studied the route profile, picked your tyres, and dialled in your bike fit. But if you haven't built a fueling plan, none of it matters past mile 60.

A century ride — whether it's a sportive, a gran fondo, or a personal challenge — is an exercise in energy management. The bike doesn't care how strong your legs are if your glycogen stores are empty. And unlike a marathon, where aid stations decide your intake, on the bike you're in complete control of what goes in your jersey pockets and your bottles.

That control is a gift. It means you can plan this perfectly. Here's how.

Why century fueling is different from marathon fueling

If you've come from a running background, forget most of what you know about race nutrition. Cycling changes the equation in three fundamental ways.

You burn more per hour. A cyclist riding at moderate intensity burns 600–900 calories per hour — roughly 30–50% more than a runner at the same heart rate. Over a six-hour century, that's 4,000–6,000 total calories. Your body stores around 2,000 calories of glycogen. The maths is brutally simple: if you don't eat on the bike, you will bonk.

Your gut can handle more. The upright-ish position on a bike, combined with less impact stress than running, means your digestive system tolerates higher volumes of food and fluid. Cyclists can comfortably consume 60–90g of carbohydrates per hour — and trained guts can push toward 100–120g. Runners often struggle to manage 60g.

You can carry more. Two bottle cages, jersey pockets, a top tube bag, a bento box — you have real estate that runners can only dream of. Use it. Running out of fuel on a century ride is a logistics failure, not a physical one.

The numbers: what your body needs for 100 miles

Before you start shopping for gels and bars, you need three numbers.

1. Carbohydrate target per hour

For most cyclists riding a century at a sustainable pace (65–75% of FTP), aim for:

• Beginner or first century: 60g of carbs per hour
• Experienced rider: 60–80g of carbs per hour
• Trained gut / competitive: 80–100g+ of carbs per hour

These aren't arbitrary. Your muscles can oxidise glucose at roughly 60g per hour through a single transporter. Add fructose (using a 2:1 glucose-to-fructose ratio), and you unlock a second transporter that pushes absorption to 90g per hour or more. Most modern sports nutrition products use this dual-transport formula.

2. Fluid intake per hour

Aim for 500–800ml per hour, adjusted for conditions:

• Cool conditions (below 18°C): 500ml per hour
• Moderate (18–25°C): 600–700ml per hour
• Hot (above 25°C): 700–800ml+ per hour

Your actual sweat rate determines the precise number. A rider sweating at 1.2 litres per hour in summer heat needs significantly more fluid than someone sweating at 0.6 litres on a cool morning. The only way to know your sweat rate is to measure it — weigh yourself before and after a hard one-hour ride, add the weight of fluid consumed, and the difference is your hourly sweat loss.

3. Sodium target per hour

Sodium matters because it's the primary electrolyte lost in sweat. Most cyclists lose between 300–1,000mg of sodium per hour, depending on sweat rate and individual sweat composition.

General targets:

• Light sweater, cool conditions: 300–500mg sodium per hour
• Moderate sweater, warm conditions: 500–700mg per hour
• Heavy sweater or hot conditions: 700–1,000mg+ per hour

If you're a salty sweater (you see white residue on your kit or taste salt on your skin), you're on the higher end. An electrolyte drink with 300–500mg sodium per 500ml bottle is a good baseline. Add a salt capsule if you need more.

Building your hour-by-hour plan

Here's a practical fueling schedule for a six-hour century ride in moderate conditions (20°C), targeting 70g of carbs and 600ml of fluid per hour.

Pre-ride (3–4 hours before start)

Eat a carb-rich breakfast: 100–150g of carbohydrates. Porridge with banana and honey, toast with jam, or a bagel with peanut butter. Nothing new, nothing high-fibre, nothing you haven't eaten before a long ride.

Drink 500ml of water with an electrolyte tab in the two hours before the start. Stop drinking 30 minutes before you roll out — a full bladder at mile 5 is not a performance advantage.

Hour 1 (miles 0–16)

Start eating at 20 minutes, not when you feel hungry. Your glycogen stores are full but they deplete faster than you think.

• 1 bottle of electrolyte drink (500ml, ~30g carbs, ~400mg sodium)
• 1 energy bar or half a flapjack (~25–30g carbs)
• Total: ~55–60g carbs, 500ml fluid

Hours 2–3 (miles 17–50)

Settle into your rhythm. This is where most of your fueling happens.

• 1 bottle of electrolyte drink per hour
• 1 gel or half a bar every 30 minutes
• Target: 70g carbs and 600ml fluid per hour
• Alternate between sweet and savoury if your palate gets bored

Hours 4–5 (miles 50–83)

This is where underfueled riders fall apart. If you've been eating consistently, you'll feel strong. If you've been skipping feeds because you "felt fine," mile 60 is where you'll pay.

• Continue the same pattern: 1 bottle and 2 gels (or equivalent) per hour
• If solid food starts to feel heavy, switch to gels and liquid nutrition
• Add an extra salt capsule per hour if conditions are hot or you're sweating heavily
• Sip, don't gulp — small, frequent intakes beat big doses

Hour 6 (miles 83–100)

The home stretch. Your glycogen stores are running on fumes regardless of how well you've fueled — you've been running a caloric deficit all day. Keep eating.

• Gels and drink only (your gut may reject solids this late)
• A caffeine gel at mile 85 can provide a genuine performance boost — 200mg of caffeine improves power output and reduces perceived effort in the final quarter of endurance events
• Don't stop fueling because you can "see the finish" — those final 15 miles at a caloric deficit can be the longest of your life

What to carry (and where to put it)

A six-hour century at 70g of carbs per hour means roughly 420g of total carbohydrates. Here's one way to carry that:

Bottles (2 x 750ml, refilled once at a stop):

• 4 bottles of electrolyte drink across the ride = ~120g carbs

Jersey pockets:

• 8–10 gels (25g carbs each) = 200–250g carbs
• 2 energy bars (30g carbs each) = 60g carbs
• 2 salt capsules (for hours 4–6 in heat)

Top tube bag:

• Spare gels for easy access
• Caffeine gel reserved for final hour

Total: ~400–430g carbs available

That's your safety margin. You probably won't eat every last gel, but carrying more than you need means you never have to ration.

The feed stop question

Most sportives have feed stops every 25–40 miles. Use them for water bottle refills and a quick top-up (a banana, a handful of sweets, a slice of flapjack). Don't use them as your primary fueling strategy — standing around eating cake at mile 50 while your legs stiffen up is not a performance plan.

Stop for 2–3 minutes, refill bottles, grab one item, and go.

The most common century fueling mistakes

Starting late. If your first food is at mile 30 because you "didn't feel hungry," you've already dug a glycogen hole that's very hard to climb out of. Start eating at 20 minutes. Every time.

Relying on one type of food. Six hours of nothing but sweet gels will make you gag by hour four. Carry a mix: gels, bars, rice cakes, salted potatoes, even a sandwich for the first half. Flavour fatigue is real and it makes athletes stop eating — which is the one thing you can't afford to do.

Drinking only water. Water alone dilutes your blood sodium without replacing what you're sweating out. After 2–3 hours, this can cause bloating, nausea, and in extreme cases hyponatremia. Every bottle should have electrolytes. If you prefer plain water, take a salt capsule every hour alongside it.

Copying a pro's nutrition plan. A professional cyclist riding a century in 3.5 hours has fundamentally different fueling needs than a sportive rider finishing in 6. The pro burns through glycogen faster but rides for less time. The amateur rides longer, can digest more per hour, and needs more total fuel. Build a plan based on your body, your pace, and your conditions — not someone else's Instagram post.

Ignoring the weather. A century ride at 15°C and one at 32°C require completely different hydration strategies. Hot conditions can increase your sweat rate by 50–100%, meaning your carefully planned 500ml per hour is suddenly 300ml too little. Check the forecast and adjust. If in doubt, drink more.

How Sweatr builds this plan for you

The framework above works. But it's generic — it gives you ranges, not your number. Your actual carb needs depend on your body weight, your intensity, and your ride duration. Your fluid needs depend on your personal sweat rate, which varies with fitness, heat acclimatisation, and conditions. Your sodium needs depend on your individual sweat composition.

Sweatr pulls your training data from Garmin and Strava, calculates your personal sweat rate from your ride history, and builds an hour-by-hour fueling plan calibrated to your body and your event. It tells you exactly how many grams of carbs, how many millilitres of fluid, and how many milligrams of sodium you need per hour — then maps that to real products you can buy and carry.

You don't have to do the maths. You don't have to guess whether you're a "light sweater" or a "heavy sweater." You get a plan built from your actual data.

Practise the plan before race day

Your body can only absorb what it's trained to absorb. If you've never eaten 70g of carbs per hour on the bike, don't try it for the first time at your century.

Start practising your fueling strategy on your weekend long rides at least 6 weeks before your event. Begin at 40–50g of carbs per hour and increase by 10g each week until you reach your target. This progressive gut training teaches your intestines to absorb more carbohydrate without GI distress.

Test the specific products you plan to use. The gel that tastes fine in your kitchen may be revolting at mile 70. The bar that's easy to chew at rest may be impossible to eat while holding 200 watts. Find out now, not on the day.

If anything causes stomach issues during training, swap it out. You have weeks to find what works. On race day, you should be executing a plan you've already proven.

The century ride fueling checklist

Use this as a final check the night before your event:

• [ ] Breakfast planned: 100–150g carbs, 3–4 hours before start
• [ ] Bottles filled: electrolyte drink, not plain water
• [ ] Carbs packed: enough for your target grams per hour, plus 20% extra
• [ ] Mix of formats: gels, bars, and at least one savoury option
• [ ] Salt capsules: 2–4 for hot conditions
• [ ] Caffeine gel: one reserved for the final 15 miles
• [ ] Feed stop strategy: refill bottles, grab one item, move on
• [ ] Tested everything: no new products on race day

A century ride is long enough that fitness alone won't carry you. The riders who finish strong aren't necessarily the fittest — they're the ones who ate and drank consistently from mile 1. Build the plan, practise the plan, and trust the plan.