Carbs per hour on the bike and on the run: how to set your number
Set your carbs per hour by how long you will be going: nothing under 45 minutes, small amounts or a mouth rinse at 45-75 minutes, 30-60 g/h for 1-2.5 hours, and up to 90 g/h beyond 2.5 hours using glucose-fructose mixes. These are the ACSM joint position statement ranges, and they apply to cycling and running alike.
Duration sets the band. Your gut, your intensity and the sport decide where in the band you sit. The rest of this post is how to choose that spot.
How many grams of carbs per hour do I need?
Find your duration in this table. It comes from the ACSM, Academy of Nutrition and Dietetics and Dietitians of Canada joint statement (Thomas, Erdman and Burke, 2016).
| Session or race length | Carbs during exercise |
|---|---|
| Under 45 min | Not needed |
| 45-75 min, hard | Small amounts, including a mouth rinse |
| 1-2.5 h | 30-60 g/h |
| Over about 2.5 h | Up to 90 g/h |
The band tells you the range. Where you land inside it depends on intensity (harder burns more carbohydrate), how well you have trained your gut, and how practical it is to eat in your sport.
Why does the number stop around 60 g/h for one sugar?
Because the gut can absorb a single sugar only so fast. Jeukendrup (2014) reports that a single carbohydrate source like glucose is used at up to about 60 g/h, and that higher intakes must be “multiple transportable carbohydrates”, typically glucose plus fructose, which use separate absorption routes.
In practice: if you are aiming above 60 g/h, check that your drink mix or gels contain both. Taking more glucose alone mostly adds to what sits in your stomach.
Is it different on the bike and on the run?
The physiology is the same, but eating is easier on the bike. Running jostles the gut, and many runners tolerate less than cyclists at the same intensity. The guidelines do not set separate numbers by sport; that difference is a practical one, and individual.
A reasonable approach:
- Cycling: you can mix bottles, gels and solid food, so the top of the band is easier to reach.
- Running: rely on gels and drinks, start at the lower end of the band, and build up in training.
What does this look like for a long ride?
Take a 4-hour endurance ride aiming for 80 g/h, within the up-to-90 band.
- Total: 4 × 80 = 320 g of carbohydrate.
- Per hour: one 500 ml bottle with 40 g of glucose-fructose mix, one 25 g gel, and half a bar of about 15-20 g, so 80-85 g.
- Over four hours: four bottles, four gels, two bars.
Start eating in the first 20-30 minutes rather than waiting until you feel empty. Small, regular intakes are easier on the gut than large ones.
What does this look like for a marathon?
Take a 3:45 marathon at 60 g/h, a common starting point for runners.
- Total: 3.75 × 60 = 225 g.
- With 25 g gels: about nine gels, one roughly every 25 minutes, or fewer gels plus sports drink at aid stations.
If you have trained your gut, you can move toward 75-90 g/h with glucose-fructose gels. For the days before the race, see our day-by-day marathon carb-load.
How do I find my own number?
Treat the band as a starting range and test it in training. A practical method:
- Pick the band from your session length.
- Start at the lower end in long training sessions.
- Raise it by about 10 g/h every week or two if your gut is fine.
- Note stomach comfort and how the last hour felt.
- Race at the amount you have already practised, never a new one.
Jeukendrup’s review recommends practising your race nutrition in training and spending some of it on high carbohydrate intakes, because the gut adapts. The 10 g/h step is our practical suggestion, not a figure from the literature.
What about 120 g per hour?
Some elite cyclists and runners now practise intakes above 90 g/h. The position stands cited here still top out at about 90 g/h, and evidence for higher rates is newer and less settled. If you try it, do so gradually and in training, not first on race day.
How sure are these numbers?
They are consensus ranges, not individual measurements. Body size, intensity, heat and gut training all move your best number. Use them to start, then let your own training tell you where you sit.
How Sweatmeal fits in
Sweatmeal sets your daily carb target around training load, so the days of your long rides and runs carry more carbohydrate than rest days, and your race calendar adds a carb-load before long endurance races. It does not set your grams per hour for you. With Pro, the coach plans meals around tomorrow’s session and can talk through your in-session fuelling. Targets, wearables and the calendar are free. The method behind the daily number is on our methodology page.