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Fuelling Long Rides: Duration, Grams per Hour and the Gut Build A ride under two hours needs water and maybe a snack. A ride over three hours is a fuelling exercise with a bike attached, and the riders who suffer are almost never undertrained — they are underfed or badly timed. Duration decides the plan…

Fuelling Long Rides: Duration, Grams per Hour and the Gut Build

A ride under two hours needs water and maybe a snack. A ride over three hours is a fuelling exercise with a bike attached, and the riders who suffer are almost never undertrained — they are underfed or badly timed.

Duration decides the plan

Ride duration_h Fuel strategy
Under 1 h Water only
1–2 h 0–30 g carbs/h, one bottle
2–3 h 60 g/h, mix of drink and solid
3–5 h 75–90 g/h, planned portions
5 h+ 90 g/h with two carb sources

Crossing from two to three hours is the step most riders get wrong: until that point glycogen covers the deficit, and after it the deficit is won or lost by intake rate.

Carbs per hour

Rider Target carbs_g_per_h Ceiling
New to long rides 40–60 75
Regular 60–75 90
Trained gut 90 120

Above roughly 60 g per hour, absorption becomes the limit rather than appetite. A 2:1 glucose-to-fructose mix uses two intestinal transporters and can push absorption towards 90 g/h, but only after adaptation.

The most common mistake is arriving at hour three having eaten 40 g total. Plan the grams before the ride, not when hunger arrives — hunger on the bike lags the deficit by 20–30 minutes.

Food forms and when they work

Form Carbs Eaten when
Drink mix 30–60 g per bottle Steady, all ride
Gels 20–25 g Hard efforts, last third
Chews 20–30 g per pack Rolling terrain
Bars 30–45 g First two hours
Bananas 25 g Easy sections, stops
Sandwiches, rice cakes 40–60 g Stops, low intensity

The rule is simple: the harder the effort, the simpler the food. Solid food during threshold efforts sits in the stomach because blood is diverted to the legs.

Eating cadence

Plan Portion Interval
Every 25 min 20–25 g Easiest to absorb
Every 30 min 30 g Works on easy sections
Every 45 min 45 g Risk of stomach load
Every 60 min 60 g Too large for most riders

Small and often beats large and rare. Taking 20 g every 25 minutes delivers 48 g/h on a schedule the stomach tolerates, while a single 60 g bar at the hour mark often causes discomfort and a dip.

Set a timer for the first few long rides. Riders consistently overestimate how much they have eaten — the timer removes the guesswork until the habit forms.

Building the gut

Week Intake Session
1–2 40 g/h Easy 2 h ride
3–4 60 g/h One long ride a week
5–6 75–90 g/h Long ride, low intensity
7+ Race intake Practise on course-like rides

Adaptation takes four to six weeks and requires low intensity while it happens. Trying 90 g/h for the first time in an event is how riders end up nauseous at kilometre 80.

Bonk signals

Signal What it means
Sudden emptiness in the legs Glycogen depleted
Irritability, decision fog Blood glucose low
Cold sweat, light head Late-stage bonk
Loss of power on familiar climbs Intake fell behind
Hunger disappears Not a good sign — eat anyway

The reliable early warning is not hunger but mood: riders who become irritable and indecisive on a long ride are usually 300–500 kcal behind. Once the cold sweat arrives, 20 minutes of easy riding and 30–40 g of fast carbohydrate are needed.

What to carry

For a four-hour ride: two bottles (one with mix), two bars, two gels, and a banana. That is roughly 210 g of carbohydrate, which covers 60 g/h with a margin for a mechanical stop or a headwind.

Refill points matter more than the total. A 100 km route with a shop at halfway needs less carried food than a 60 km loop with nothing — and carrying less means a lighter, faster bike.

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