On a bike ride of 1 to 2.5 hours, you need 30 to 60 g of carbohydrates per hour; past 2.5 hours, up to 90 g per hour, as long as you use products that mix glucose and fructose and your stomach is used to it. On rides of an hour or less, you don’t need to eat. For fluids, the benchmark is to lose no more than 2% of your body weight during the ride, and on hot days you should replace sodium as well.
These numbers come from the position stands of the American College of Sports Medicine (ACSM) and the International Society of Sports Nutrition (ISSN), and from reviews by Louise Burke and Asker Jeukendrup, two of the leading names in sports nutrition. Below is how to apply them to your ride, with examples in grams.
Note: this guide summarizes general recommendations for healthy people. It isn’t medical advice. If you have diabetes, kidney or heart disease, high blood pressure, or take medication, talk to your doctor or a registered dietitian before changing what you eat or drink on the bike.
How many carbs to eat based on ride length
Your body stores glycogen (its carbohydrate reserve) in the muscles and liver, but it doesn’t last much beyond 90 minutes of sustained effort. After that, what you eat on the bike makes the difference between finishing strong and running on empty, what cyclists call bonking.
| Ride length | Carbs per hour | What kind |
|---|---|---|
| Under 1 hour | None | Eating beforehand is enough |
| About 1 hour, hard | Very little (even just rinsing your mouth with a sports drink) | Any |
| 1 to 2.5 hours | 30-60 g | Any: glucose, maltodextrin, sucrose |
| Over 2.5 hours | Up to 90 g | Glucose and fructose mix |
Source: Burke et al. (2011), a review co-authored by Jeukendrup.
Three important caveats:
- 60 g/h is the ceiling for a single type of sugar. Your gut absorbs glucose at a maximum of about 60 g per hour. To reach 90 g you need to combine it with fructose, which is absorbed through a different pathway; according to Jeukendrup (2014), that lets you oxidize up to 75% more carbohydrate.
- The high numbers are for trained cyclists. Jeukendrup himself points out that people riding at an easy pace or just starting out may need less, because you burn fewer carbs at low intensity. If you’re riding at 120-140 W, 30-45 g/h usually works fine.
- You can train your gut. Practicing your fueling plan in training reduces stomach problems. Don’t try new gels or drinks on the day of a big group ride or gran fondo.
A practical example
A 3-hour endurance ride (around 150 W) calls for 30-60 g/h, or 90 to 180 g total. An easy way to split it up:
- First hour: one 25 fl oz (750 ml) bottle of a 6% sports drink (45 g of carbs).
- Second hour: an energy bar and half a bottle of drink mix.
- Third hour: a gel and the rest of the drink.
Always check the label: grams of carbs per serving vary a lot from one product to another. A “6%” drink has 60 g of carbs per liter (about 34 fl oz); the ISSN recommends concentrations of 6-8%, sipped every 10-15 minutes.
How much you burn and why you don’t need to replace it all
With a power meter, energy use is easy to calculate: every kilojoule you put into the pedals equals a little more than one calorie (kcal) burned by your body, because a cyclist’s efficiency is about 24%. With our cycling calorie calculator:
| Average power | Calories per hour | Over 4 hours |
|---|---|---|
| 120 W | 430 kcal | 1,721 kcal |
| 150 W | 538 kcal | 2,151 kcal |
| 180 W | 645 kcal | 2,581 kcal |
| 200 W | 717 kcal | 2,868 kcal |
If you don’t have a power meter, the chart of cycling calories by speed gives you an estimate based on MET values.
60 g of carbs is 240 calories: even if you eat the recommended amount, you’re covering less than half of what you burn. That’s fine. The goal on the bike isn’t to replace calories, it’s to keep your blood sugar up and spare glycogen; fat makes up the rest, and you recover it at your next meals.
Before you ride: breakfast and carb loading
- Pre-ride meal: the ISSN position stand recommends 1-4 g of carbs per kilogram of body weight in the hours before. For 165 lb (75 kg), that’s 75 to 300 g: about 75-100 g if you eat an hour before (for example, toast with jam and a banana) and quite a bit more if it’s a full meal 3-4 hours before.
- Low fat and low fiber in that last meal: they digest slowly and can upset your stomach once you start working hard.
- Carb loading: it only makes sense before events longer than 90 minutes of continuous hard riding. The ISSN talks about 8-10 g per kilogram per day for 1-3 days while cutting back on training. For a weekend ride, a good dinner the night before is enough.
How much to drink
The ACSM sets the target at losing no more than 2% of your body weight from fluid loss: 3.3 lb (1.5 kg) for a 165 lb (75 kg) person. Beyond that, performance drops. But the exact amount varies a lot from person to person:
- You can sweat 17 to 68 fl oz (0.5 to 2 liters) per hour, depending on heat, intensity and the individual (review by Lindsay Baker, 2017).
- How to measure your own: weigh yourself without clothes before and after a one-hour ride, without peeing in between. Each pound lost is roughly 15-16 fl oz (450 ml) of sweat; add what you drank and you have your sweat rate per hour.
- Don’t overdrink either. The Sports Dietitians Australia position statement (2020) warns against both drinking too little and drinking too much. If you finish a ride weighing more than when you started, you drank too much.
As a rule of thumb, start with one bottle (17-25 fl oz, or 500-750 ml) per hour on mild days and fine-tune it based on your weight change. In summer, carry two bottles and have a plan to refill at stores, gas stations or water fountains.
Sodium: when you need it
Sweat isn’t just water. According to Baker’s review, it contains 10 to 70 mmol of sodium per liter, which is about 230 to 1,610 mg per liter. That’s a huge range between people: some cyclists are “salty sweaters” (their jersey and helmet straps end up with white salt stains) and others lose very little.
- Rides under 2 hours: you don’t need extra sodium; your normal diet covers the loss.
- Long rides in the heat or with heavy sweating: use an electrolyte drink or salt tablets. Check the label for how much sodium each bottle provides and compare it with what you lose: if you sweat about 34 fl oz (1 liter) per hour at 900 mg of sodium per liter, you lose about 900 mg every hour.
- If you finish with white salt stains on your jersey or helmet, you’re one of the people who lose the most sodium: on long rides, choose an electrolyte drink over plain water.
After the ride
If you’re riding again within 4 hours, the ISSN recommends eating carbs right away (up to 1.2 g per kilogram per hour, about 90 g per hour at 165 lb) or combining them with protein (0.8 g/kg/h of carbs and 0.2-0.4 g/kg/h of protein). If you’re not in a hurry, a normal meal with carbs and 20-40 g of protein within the next 2 hours is enough.
Common mistakes
- Waiting until you’re hungry or thirsty. By then you’re already late. On rides over 90 minutes, start eating within the first 30-45 minutes.
- Copying the pros. The 90 g/h or more they take in at Grand Tours is for 5-hour efforts at high intensity, with a very well-trained gut.
- Trying something new on event day. Gel, drink mix or bar: test everything in training first.
- Drinking only water for 4 hours in the heat. Replace carbs and sodium, not just fluid.
- Eating a greasy meal right before you ride. Better something light and carb-rich one or two hours before.
If you’re getting ready for a specific ride, you’ll find the full plan in how to prepare for your first big climb, and the training zones guide tells you what intensity you’re riding at.
Frequently asked questions
How many carbs per hour should I eat when cycling?
It depends on how long you ride: for a one-hour ride, little or nothing; for 1 to 2.5 hours, 30-60 g per hour; and for more than 2.5 hours, up to 90 g per hour, using products that mix glucose and fructose (Burke et al., 2011).
How much water should I drink on a bike ride?
Enough to lose no more than 2% of your body weight (3.3 lb if you weigh 165 lb, or 1.5 kg at 75 kg), according to the ACSM. Weigh yourself before and after a typical ride: each pound lost is roughly 15-16 fl oz (450 ml) of sweat you didn't replace.
Do I need electrolytes on a bike ride?
Not on short rides. On long rides in the heat, it makes sense to replace sodium: sweat carries roughly 230 to 1,600 mg of sodium per liter depending on the person, and you can sweat 17 to 68 fl oz (0.5 to 2 liters) per hour.
What should I eat before a long bike ride?
A carb-rich meal 1 to 4 hours before: the ISSN position stand suggests 1-4 g of carbs per kilogram of body weight. For 165 lb (75 kg), that's 75 to 300 g: the closer to the ride, the less food and the less fiber and fat.
Do I need to replace all the calories I burn while cycling?
No. At an average of 200 W you burn about 720 calories per hour, and 60 g of carbs per hour gives you only 240: a third. The rest comes from your glycogen and fat stores, and you replace it with your meals afterward.
Sources
- Burke L. M., Hawley J. A., Wong S. H., Jeukendrup A. E., "Carbohydrates for training and competition," J Sports Sci 29 Suppl 1 (2011)
- Jeukendrup A., "A step towards personalized sports nutrition: carbohydrate intake during exercise," Sports Med 44 Suppl 1 (2014)
- Kerksick C. M. et al., "International Society of Sports Nutrition position stand: nutrient timing," J Int Soc Sports Nutr 14 (2017)
- Thomas D. T., Erdman K. A., Burke L. M., "American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance," Med Sci Sports Exerc 48(3) (2016)
- American College of Sports Medicine, Sawka M. N. et al., "Exercise and fluid replacement," Med Sci Sports Exerc 39(2) (2007)
- Baker L. B., "Sweating rate and sweat sodium concentration in athletes: a review of methodology and intra/interindividual variability," Sports Med 47 Suppl 1 (2017)
- McCubbin A. J. et al., "Sports Dietitians Australia position statement: nutrition for exercise in hot environments," Int J Sport Nutr Exerc Metab 30(1) (2020)