The “Peak Carbs” Era — How Much Carbohydrate Should Age-Groupers Eat on the Bike?

The “Peak Carbs” Era: How Much Should You Actually Eat on the Bike?

For decades, endurance nutrition advice converged on a simple rule: don’t eat more than about 60 grams of carbohydrate per hour, because your gut can’t absorb more. Then pro triathletes and WorldTour cyclists started publicly reporting race-day intakes of 120, 150, even 170 grams per hour, and the old ceiling started to look outdated overnight. Triathlon media now talks about a “peak carbs” era — but before you start doubling your gel intake for your next race, it’s worth separating what the science actually supports from what’s elite-specific social media flexing.

The short version: the shift away from 60g/hour is real and well-supported by exercise metabolism research — but it tops out, for most age-groupers, somewhere around 90–120g/hour, not 150–170g/hour. Getting there safely requires deliberate practice, not a sudden jump on race morning.

Where the Old 60g/Hour Rule Came From

The traditional ceiling wasn’t arbitrary — it reflected a real physiological bottleneck. When you ingest glucose alone, your intestine relies on a single transporter (SGLT1) to move it into the bloodstream, and that transporter has a limited capacity. Exercise metabolism research consistently found that this caps exogenous carbohydrate oxidation — the rate at which ingested carbohydrate can actually be used as fuel — at roughly 60 grams per hour when using glucose alone, no matter how much more an athlete tried to swallow. Eating beyond that ceiling with glucose alone mostly just meant unabsorbed carbohydrate sitting in the gut, a recipe for bloating and GI distress rather than extra fuel.

What Changed: Glucose-Fructose Blends

The real breakthrough behind the higher intake numbers isn’t a change in how much the gut can absorb overall — it’s the discovery that combining glucose and fructose uses two separate intestinal transport pathways instead of one. Because fructose is absorbed via a different transporter than glucose, blending the two lets an athlete take in more total carbohydrate without simply overwhelming a single bottleneck. This finding has been replicated across multiple studies and raises the practical oxidation ceiling from roughly 60g/hour (glucose alone) to approximately 90g/hour with a well-formulated glucose-fructose blend — this is the evidence base behind most modern commercial energy drink mixes and gels that use a roughly 2:1 glucose-to-fructose (or maltodextrin-to-fructose) ratio.

How High Can You Realistically Go?

More recent research has pushed the question further: how much can athletes tolerate above 90g/hour, and does the body actually use it? Studies testing glucose-fructose intakes of around 120 grams per hour over roughly 3 hours of moderate-intensity cycling found this was reasonably well tolerated — but oxidation efficiency (the percentage of ingested carbohydrate the body actually burns as fuel, versus what stays unused) dropped to around 75%. In other words, going from 90g to 120g/hour does deliver more usable fuel, but with diminishing returns — not every additional gram translates one-for-one into extra energy.

At the very top end of the range, the picture gets thinner and more individual. A detailed 2025 interview with exercise physiologist Tim Podlogar, who has worked with WorldTour cycling teams, reported that documented maximal absorption in some individuals reaches roughly 180 grams per hour with added fructose — but he was explicit that these are rare, outlier cases that don’t necessarily translate into better performance for anyone else. Podlogar also made an important distinction: there is no good evidence that gut absorption capacity itself can be trained upward. What can genuinely be trained is an athlete’s tolerance — the ability to ingest a large volume of carbohydrate and fluid without triggering GI distress — through repeated, deliberate practice.

So What Should Age-Groupers Actually Target?

Pulling this together, the evidence-informed guidance reported in triathlon-focused coverage of this research suggests most age-group athletes should target roughly 90–120 grams of carbohydrate per hour during racing, with smaller or lighter athletes generally sitting toward the lower end of that range. This is a genuinely evidence-backed step up from the old 60g/hour dogma — but it is meaningfully below the 150–170g/hour figures that circulate on social media, which remain largely elite or individual-outlier reports rather than a target the average age-grouper should chase.

Two other pieces of evidence-based context matter here. First, carbohydrate and hydration/heat stress interact: research on training and competing in the heat, and on carbohydrate periodization in trained triathletes, indicates that heat stress can offset some of the metabolic adaptations athletes might expect from their fueling and training choices — a reminder that fueling plans need to account for conditions on race day, not just a fixed gram target. Second, a common and practical race-execution pattern described in triathlon bike-nutrition coaching content is to front-load carbohydrate intake on the bike leg, then deliberately taper it down heading into the run — “fuel the bike, save the run” — as a way of limiting GI load during the discipline where a stressed gut is most likely to end your race.

A Worked Example: Fueling a Half-Ironman Bike Leg

To make the 90–120g/hour range concrete, consider a typical age-group athlete spending roughly 3 hours on the bike leg of a half-Ironman. Targeting 90g/hour means consuming roughly 270g of carbohydrate across the ride — commonly delivered as a combination of a concentrated carbohydrate drink mix (which can supply 60–90g/hour on its own with a glucose-fructose blend) plus one or two gels for variety or for aid-station convenience. An athlete experimenting toward the upper end of the evidence-supported range, say 110–120g/hour, would be looking at roughly 330–360g of carbohydrate for the same 3-hour ride — a substantial volume of product and fluid that has to be practiced, not improvised.

The practical takeaway from the research is less about hitting an exact gram target and more about deliberately testing where your own comfortable ceiling sits, then building your race plan around a number you’ve already proven you can tolerate at race intensity — rather than a number you read about a professional athlete using.

Practical Application: Building a Race-Day Fueling Plan

Turning this evidence into a workable plan comes down to three phases: establishing a baseline, gradually raising your ceiling in training, and then executing a tapered plan on race day.

• Start from where you are. If you currently take in 40–60g/hour and tolerate it fine, that is a reasonable, safe baseline — not a failure. The goal of raising intake is to unlock more usable fuel for long or hard efforts, not to hit an arbitrary number.
• Choose a glucose-fructose (or maltodextrin-fructose) blend, roughly in a 2:1 ratio, rather than glucose-only products, if you want to push meaningfully above 60g/hour — this is the combination the research base actually supports for raising the oxidation ceiling toward 90g/hour and beyond.
• Raise intake gradually in training, not on race day. Add roughly 10–15g/hour every couple of long rides, paying close attention to GI comfort, and only keep a higher number if it’s genuinely well tolerated across more than one session — not just once.
• Practice at race intensity and, where possible, in race-like heat, since gut tolerance can behave differently under harder efforts and in hot conditions than during easy long rides.
• On race day, front-load your intake on the bike — where GI tolerance is generally more forgiving than on the run — and plan a deliberate step-down in carbohydrate intake in the final 30–45 minutes of the bike leg heading into transition, to reduce GI load exactly when you need your gut calmest.
• Pair carbohydrate intake with your hydration and sodium plan rather than treating them separately — concentrated carbohydrate intake without adequate fluid can itself contribute to GI discomfort, particularly in heat.

A Note on Safety, GI Risk, and Individual Variability

This is a nutrition topic with real, race-ending risk if implemented carelessly. Suddenly attempting a high carbohydrate intake (100g/hour or more) on race day without having practiced it in training is a well-documented cause of GI distress — cramping, bloating, nausea, or worse — and has ended plenty of otherwise well-prepared athletes’ races. Carbohydrate tolerance is also highly individual: what one athlete handles comfortably at 120g/hour may cause real problems for another at 80g/hour, and there is no shortcut around personal testing in training. Athletes with pre-existing gastrointestinal conditions, such as irritable bowel syndrome, should be especially cautious and are encouraged to seek individualized guidance from a sports dietitian or physician rather than following general population-level targets. None of the ranges discussed here are a substitute for personalized metabolic or GI-tolerance testing where that’s available to you.

Common Mistakes Age-Groupers Make With Bike Nutrition

• Trying a brand-new fueling product or a meaningfully higher carbohydrate intake for the first time on race morning — the single most avoidable cause of race-day GI failure.
• Assuming the 90–120g/hour range is a universal requirement rather than a research-informed ceiling — plenty of age-groupers perform well on 60–80g/hour, and there’s no evidence that everyone needs to push higher to race well.
• Chasing the 150–170g/hour numbers reported by pro athletes on social media, without acknowledging these are outlier, individually documented cases rather than a population-level target.
• Treating carbohydrate intake and hydration as separate problems, when in practice concentrated carbohydrate without enough fluid can itself provoke GI symptoms.
• Failing to taper carbohydrate intake down before the run, carrying a bike-leg fueling rate straight into the run leg where GI tolerance is typically lower.
• Ignoring personal GI history — athletes with known sensitivity or conditions like IBS pushing standard “peak carbs” targets without individualized guidance from a professional.
• Relying entirely on aid-station nutrition on race day without having tested that exact product beforehand, introducing an unfamiliar variable at the worst possible time.
• Under-fueling out of fear of GI distress and swinging too far in the other direction, risking a bonk on the run because the bike leg was deliberately under-fueled relative to what the athlete had actually shown they could tolerate in training.

How to Apply This Week

• On your next long ride, record exactly how many grams of carbohydrate per hour you currently take in, and rate your GI comfort on a simple 1–5 scale — this is your real baseline, not a guess.
• Check the glucose-to-fructose ratio on your current gels or drink mix; if it’s glucose/maltodextrin-only and you want to raise your ceiling, look for a product blended closer to 2:1 glucose-to-fructose.
• Plan one long ride this week where you increase your intake by roughly 10–15g/hour over your usual amount, at an intensity similar to race pace, and track how your gut responds.
• Sketch a simple race-day fueling timeline: grams per hour for the first half of the bike, grams per hour for the second half, and a specific step-down point before you get off the bike.
• If you have any history of GI issues, IBS, or persistent bike-leg nausea, use this week to book time with a sports dietitian rather than self-experimenting further at higher intakes.

Closing Summary

The shift away from the old 60g/hour rule is real and grounded in solid exercise metabolism research: glucose-fructose blends genuinely raise the practical fueling ceiling, and most age-group triathletes can likely benefit from targeting somewhere in the 90–120g/hour range during racing. But the highest-end numbers you see reported by pro athletes — 150g/hour and beyond — are not well-supported as a target for typical age-groupers, and pushing your own intake higher only works if you build up tolerance gradually in training, choose an appropriate glucose-fructose product, and pair it sensibly with hydration and a plan to taper down before the run. Treat this as a personal experiment guided by evidence, not a number to copy from someone else’s Instagram post — and get professional input if you have any GI history that makes self-experimentation risky.

References

• How Should Triathletes Handle the “Era of Peak Carbs?” — Triathlete.com
• 90 vs 120g of Carbohydrates for Endurance Performance — EndureIQ (summarizing peer-reviewed exogenous CHO oxidation literature)
• Consensus recommendations on training and competing in the heat — British Journal of Sports Medicine, 2015
• Environmental heat stress offsets adaptation associated with carbohydrate periodization in trained male triathletes — PubMed
• Triathlon Bike Nutrition: Fuel the Bike, Save the Run — Roadman Cycling