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Endurance riders have quietly doubled how much they eat on the bike over the past fifteen years. The old advice of a gel an hour has become 60, 90, sometimes more grams of carbohydrate per hour — and the riders doing it are not, mostly, getting sick. That is because the number is only half the story. What you can absorb depends on the type of carbohydrate and on how often you have asked your gut to do the job.
This article covers where the 90 g/h figure comes from, why a glucose-and-fructose mix is the thing that makes it possible, and how to build up to it over a couple of months without spending a long ride hunched over a hedge.
Gut symptoms during exercise are common and usually benign, but they can also be a sign of something that has nothing to do with fuelling. Persistent pain, blood, unexplained weight loss or symptoms that continue away from the bike are a reason to see a doctor, not to adjust your gel brand. If you have a diagnosed gastrointestinal condition, talk to a dietitian before changing intake substantially.
Why 60 g/h used to be the ceiling
Glucose leaves the gut through a specific transporter, SGLT1. Like any transporter, it saturates: once every copy is busy, extra glucose sits in the intestine drawing water in rather than being absorbed. In practice, exogenous glucose oxidation tops out near 1 g per minute — about 60 g per hour — no matter how much more you swallow. Eating more glucose past that point buys you nausea, not watts.
Fructose is absorbed by a different route, GLUT5. Combine the two and you are using two doors instead of one. Studies comparing glucose alone with glucose-plus-fructose at the same total intake have repeatedly shown higher exogenous carbohydrate oxidation rates with the mixture — roughly up to 1.5 g/min, and in some work higher still. That is the whole basis for the modern numbers.
Glucose · SGLT1
saturates near 60 g/h
Glucose, maltodextrin and starch all arrive at this door. Once it is full, extra glucose stays in the gut.
Fructose · GLUT5
a second, independent route
Adding fructose alongside glucose raises total absorption instead of competing for the same transporter.
The two ratios you will see on packaging are 2:1 glucose to fructose and 1:0.8. Both are defensible. The 1:0.8 ratio came out of work testing a range of fructose-to-maltodextrin blends, where the more fructose-rich mixture produced good oxidation with less reported gut discomfort. Treat the difference between them as small and personal rather than decisive — the ratio matters far less than whether there is any fructose in there at all.
How much, by how long you are riding
Intake guidance scales with duration, not with how serious you feel. These are rounded guides, not prescriptions, and individual tolerance varies considerably.
| Ride duration | Carbohydrate | Notes |
|---|---|---|
| Under 45 min | Nothing needed | Muscle glycogen covers it. A mouth rinse may help in a hard race, but food is optional. |
| 45–75 min | Small amounts | A mouthful of drink mix or a few sips of something sweet is plenty. This is mouth-and-brain territory, not fuel supply. |
| 1–2 hours | ~30 g/h | Single carbohydrate source is fine at this rate — glucose or maltodextrin alone saturates nothing. |
| 2–3 hours | ~60 g/h | Around the ceiling for glucose on its own. Most riders manage this with ordinary bars, gels and drink. |
| 2.5 hours and up | up to 90 g/h | Only worth chasing with a glucose-plus-fructose mix, because glucose-only transport is already maxed out. |
| Ultra-distance | 90 g/h+ | Higher rates are used in professional racing. The evidence that they beat 90 g/h in a single event is thin — see the caveat below. |
Professional riders are reported to fuel at 100–120 g/h and more. It is worth being honest about the evidence: controlled studies comparing those rates with 60–90 g/h have not clearly shown a performance advantage in a single event. The plausible case for them is recovery and energy balance across multi-day racing, which is not most people's problem. If you are riding a four-hour sportive, 90 g/h is an ambitious target already.
The gut adapts — that is the useful part
Absorption capacity is not fixed. Repeatedly delivering carbohydrate to the intestine appears to upregulate the transport machinery, and the effect shows up in fairly short training studies. In one 28-day study, endurance cyclists on a high-carbohydrate intake increased the amount of ingested glucose they actually oxidised during a steady 100-minute ride, while a matched lower-carbohydrate group did not. Shorter gut-training protocols in runners have reported reduced gut discomfort and better tolerance of feeding during exercise, with the caveat that performance effects were modest.
So the practical claim is well supported in one direction — practise eating and you will tolerate more — and weaker in the other, which is that this reliably makes you faster on the day. Tolerance is still worth having. Most fuelling disasters are not caused by eating too little; they are caused by eating a quantity the rider has never rehearsed.
A gut-training block that works
Six to eight weeks, one ride a week. Change one thing at a time and keep the rest boring.
Establish a baseline. Note honestly what you take per hour on long rides — most riders over-estimate by a wide margin.
Add roughly one extra gel or half a bottle of mix per hour on the long endurance ride only. Keep hard days as they were.
Same ride, same jump. By now you should be using a 2:1 or 1:0.8 glucose-to-fructose product rather than glucose alone.
Take your target rate during a ride that actually resembles the event — same pace, same products, same bottles.
- Use the products you will race with. A gut trained on one drink mix has not necessarily been trained on another.
- Drink enough alongside it. Concentrated carbohydrate with too little fluid is a reliable way to feel awful. Our guide to hydration strategy covers the other half of this.
- Spread the intake. Small amounts every 15–20 minutes sit far better than 90 g arriving in one go at the top of the hour.
- Back off when a jump goes badly. Drop to the previous rate, hold it for two more rides, then try again. Nothing is lost.
- Be careful with fibre and fat before long events. Both slow gastric emptying, and neither is what you want sitting in the stomach at hour three.
Turning it into a plan
The block above only works if you know in advance which ride is the long one and roughly how long it will take. That is the mundane reason a structured plan helps here: when your week is written down, the fuelling rehearsal has somewhere to live. Moveee's adaptive training plans schedule the long endurance ride explicitly, and its Route Engine gives you a realistic duration for a route before you leave — which is the number your fuelling plan actually depends on.
For the broader numbers on race-day fuelling, see fuelling long rides. And if it is winter, indoor sessions are the easiest laboratory you will ever have — the kitchen is four steps away and nothing is at stake.
Sources 7
Where this article summarises a study, the study itself is linked — not a write-up of it.
- 1 Jeukendrup AE A step towards personalized sports nutrition: carbohydrate intake during exercise · Sports Medicine · 2014
- 2 Podlogar T, Wallis GA New horizons in carbohydrate research and application for endurance athletes · Sports Medicine · 2022
- 3 Thomas DT, Erdman KA, Burke LM Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: nutrition and athletic performance · Medicine & Science in Sports & Exercise · 2016
- 4 Cox GR, Clark SA, Cox AJ, et al. Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling · Journal of Applied Physiology · 2010
- 5 Costa RJS, Miall A, Khoo A, et al. Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance · Applied Physiology, Nutrition, and Metabolism · 2017
- 6 O'Brien WJ, Rowlands DS Fructose-maltodextrin ratio in a carbohydrate-electrolyte solution differentially affects exogenous carbohydrate oxidation rate, gut comfort, and performance · American Journal of Physiology: Gastrointestinal and Liver Physiology · 2011
- 7 Wilson PB A narrative review of the high-carbohydrate fueling revolution (≥ 100 g/h) in the professional peloton · Sports Medicine · 2025
A plan that knows how long tomorrow is
Moveee builds your week from your own rides and keeps it honest about duration and intensity — which is the number every fuelling decision on this page depends on. Free coaching, and it adapts when life gets in the way.
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