Carbohydrates during cycling exercise: why the complex mix wins
TL;DR — For rides of 1 to 4 hours, a mix of two sugars beats a single source. Glucose alone hits a wall at around 60 grams per hour; with glucose and fructose together, you can aim for 90. But the mix is about more than just sugars: combining liquid and solid food works better than relying on a single form. Use a sports drink as your base, add 1 to 2 bars per hour, starting in the first half-hour.
Consuming carbohydrates while cycling isn't about getting as many carbs in as possible. It's about getting carbs that your gut can actually absorb. And that is where a mix outperforms a single source in two ways simultaneously. I laid out the broad foundation for fueling on the bike in the complete guide to energy bars and cycling. Here, we are focusing on the zone where most riders spend their time: the 1 to 4-hour ride.
What "the mix" actually means
The term is usually used to refer to the sugars: glucose and fructose together instead of glucose alone. That is correct, and it is half the story.
The other half is the form. Drinks, solid food, and gels behave differently in your stomach. Anyone who gets everything from one form will run into the limits of that form. Chewing through four or five bars an hour is impossible when riding at tempo. And drinking a liter and a half of sugar water per hour does your stomach no favors, either.
A good strategy therefore involves two types of mixing: two sugars, and two forms. That is the entire idea behind this piece.
Why a single source fails on a 1 to 4-hour ride
Under 60 minutes, you don't need anything on the road. Your glycogen—the sugar reserve in your muscles and liver—covers that. Above that, things start to get tight, and from 75 to 90 minutes onwards, you need external carbs to maintain your power output.
Glucose enters your blood through a single transport channel in your intestinal wall called SGLT1. That channel reaches its ceiling at around 60 grams per hour. That ceiling is biological, not mental: you cannot willpower your way through it. If you put more glucose in, the excess won't be absorbed; it stays in your gut and draws in fluid. Cramps, bloating, nausea.
On a 90-minute ride, that ceiling isn't a problem, as you are well under it. On a three-hour ride, it is. This is exactly where the mix starts to count.
What the mix of sugars achieves
Fructose uses a different channel than glucose: GLUT5. This is independent of SGLT1 and isn't full when glucose hits its ceiling. With two parts glucose to one part fructose, you use both routes simultaneously. I went deeper into how that ratio works in glucose-fructose and the 2:1 ratio.
The effect has been measured, not just theorized. Currell and Jeukendrup had trained cyclists ride for two hours and then perform a time trial. The group using glucose and fructose in a 2:1 ratio rode that time trial 8% faster than the group on glucose alone, and 19% faster than those on water. Additionally, Jeukendrup and Moseley demonstrated that this same ratio accelerates gastric emptying, allowing both fuel and fluids to flow through more quickly.
That is the gain: not just increased absorption, but also faster throughput. Two things that, at the three-hour mark, make the difference between attacking on the Muur and merely surviving until the finish line.
The second mix: combining liquid and solid
This part is the one most often overlooked. Solid food and drinks are not interchangeable; they complement each other.
Drink is your base. It provides carbs and fluids simultaneously, it passes through with every heartbeat, and you don't have to chew it. At high intensity, that is an advantage you shouldn't discard: the harder you ride, the harder chewing becomes and the more sensitive your stomach is to solid food.
Solid food is your supplement. It gives you something to chew on, it is more filling, and it breaks the monotony of sweet water. On long, steady stretches, it goes down without problems. I compared when a gel is smarter than a bar and vice versa in energy bar versus energy gel.
The practical rule that follows: build your hour around the water bottle and supplement with bars. Not the other way around.
How much per hour, by ride duration
| Ride duration | Carbs per hour | Mix needed? | Practical |
|---|---|---|---|
| Under 1 hour | 0 | No | Water suffices |
| 1 to 2.5 hours | 30 to 60 g | Not strictly | Bottle plus 1 bar per hour |
| 2.5 to 4 hours | 60 to 90 g | Yes, 2:1 | Bottle plus 1 to 2 bars per hour |
| Over 4 hours | Up to 90 g, higher after gut training | Yes, 2:1 | Same rhythm, sustain longer |
I worked out the numbers per discipline and per intensity in how many carbohydrates you need per hour on the bike.
My fueling plan for 1 to 4 hours
You will never get 60 to 90 grams per hour from bars alone. That would be four or five per hour, and nobody is chewing that away at tempo. This is what it looks like.
Every hour
500 to 800 ml of sports drink with 6 to 8 grams of carbs per 100 ml. That provides 30 to 60 grams. Add 1 to 2 fruit performance bars, good for 20 to 40 grams. Together, you are in the 60 to 90-gram zone.
Start early, spread intake
Eat your first bar within the first half-hour, before you feel hungry. After that, have one bar around the start of the hour and the second halfway through. Drink continuously, in small sips. If you feel hunger on the bike, you are already too late and are going to have to catch up. Catching up means too much at once, and that is where the problems begin.
On the hard sections
Chewing is difficult when your breathing is heavy. Plan your solid food for the flat and steady sections, not halfway up a climb or during a technical segment. That is when you should drink.
Where the upper limit lies
More than 90 grams per hour is not automatically better. In a study on three hours of cycling, riders performed best on 90 grams per hour in a 2:1 ratio. At 100 grams per hour, performance in the subsequent time trial decreased because the excess could no longer be absorbed and the riders had to rely more heavily on their own muscle glycogen stores.
Higher intakes do exist, but those are not goals you set in a single ride. They belong to months of systematic building. How you handle that is in the protocol to train your gut to 90 grams per hour. Start at 60, build up during training, and never test anything new in a race.
Why fruit already has the mix
Fruit naturally provides glucose and fructose side by side. That makes the 2:1 ratio achievable without synthetic shortcuts. No maltodextrin, no artificial sweeteners, no colorings.
My bars are built on that: 80 grams of carbs per 100 grams, 20 grams per 25-gram bar, in a 2:1 ratio. Vegan, gluten-free, and lactose-free, with nothing artificial. Soft enough to eat while riding, sturdy enough to survive your back pocket. The ratio is in the product, so you don't have to calculate anything on the road.
The mix wins, in both meanings
Two sugars instead of one, because your gut has two routes. Two forms instead of one, because your stomach can't handle four bars an hour and your head can't handle two liters of sugar water.
No gel. No brick. Fuel during exertion. Fuel your flight.
Scientific foundation
The mix improves performance. After two hours of cycling, trained riders performed a time trial 8% faster using glucose and fructose in a 2:1 ratio compared to glucose alone, and 19% faster than on water (Currell & Jeukendrup, 2008).
The mechanism behind it. That same ratio accelerates gastric emptying and fluid flow compared to glucose alone, making fuel available more quickly (Jeukendrup & Moseley, 2010).
Where the limit lies. For three hours of cycling, 90 grams of carbs per hour in a 2:1 ratio was the optimal dose. At 100 grams per hour, performance in the subsequent time trial dropped because the excess could no longer be absorbed (King et al., 2019).
Sources
Currell K, Jeukendrup AE (2008). Superior endurance performance with ingestion of multiple transportable carbohydrates. Medicine & Science in Sports & Exercise, 40(2), 275-281. doi:10.1249/mss.0b013e31815adf19
Jeukendrup AE, Moseley L (2010). Multiple transportable carbohydrates enhance gastric emptying and fluid delivery. Scandinavian Journal of Medicine & Science in Sports, 20(1), 112-121. doi:10.1111/j.1600-0838.2008.00862.x
King AJ, O'Hara JP, Arjomandkhah NC, et al. (2019). Liver and muscle glycogen oxidation and performance with dose variation of glucose-fructose ingestion during prolonged (3 h) exercise. European Journal of Applied Physiology, 119, 1157-1169. doi:10.1007/s00421-019-04106-9
Frequently Asked Questions
What exactly is a complex carbohydrate mix?
Two things at once. First, two sugars: glucose and fructose in a 2:1 ratio, so you use two transport channels in your gut instead of one. Second, two forms: drink as a base, solid food as a supplement. Getting everything from one sugar or one form reaches a limit sooner than the combination.
From what ride duration do I need carbs on the road?
Under an hour, no: your own sugar reserve covers that and water is sufficient. From 75 to 90 minutes, you need external carbs to maintain your power. Between 1 and 2.5 hours, count on 30 to 60 grams per hour; above that, 60 to 90 grams.
How many bars do I eat per hour?
One to two, alongside 500 to 800 ml of sports drink with 6 to 8 grams of carbs per 100 ml. Together, this gets you to 60 to 90 grams per hour. Four or five bars an hour is not a realistic plan: you can't chew that away at tempo and your stomach handles it worse than a spread-out intake.
Why does glucose alone fail at around 60 grams per hour?
Glucose enters your blood via the SGLT1 channel in your intestinal wall, which is full at around 60 grams per hour. That ceiling is biological and cannot be circumvented by swallowing more. What enters above that amount stays in your gut and draws in fluid, resulting in cramps and nausea.
Can I consume more than 90 grams of carbs per hour?
Consume, yes, but absorb, not necessarily. In three hours of cycling, 90 grams per hour was the optimal dose, and at 100 grams per hour, performance in the subsequent time trial decreased. Higher intakes exist but belong to months of systematic buildup, not a single ride.
Why is it better to chew on flat sections?
The higher the intensity, the harder chewing becomes and the more sensitive your stomach reacts to solid food. Plan your bars for the quiet and flat sections and drink during climbs and technical passages. This way, you get your carbs in without taxing your stomach at the wrong time.
