60 or 90 g of carbs per hour? Your complete race-day fueling plan: the 2:1 glucose-fructose mix, gut training in 28 days and your heat strategy.
"How many carbohydrates per hour do I need in a race?" The honest answer is a rule of thumb based on race duration: under one hour, small amounts or even just a carbohydrate mouth rinse are enough, for 2–3 hours it is around 60 g per hour from a single source, and beyond roughly 2.5 hours up to 90 g per hour — but only via the glucose:fructose combination at a 2:1 ratio.
60 g is roughly two gels; 90 g more like three plus a bottle of mix. A typical XCO race lasts 96 ± 7 minutes, a marathon considerably longer — so your fueling plan co-decides your result.
And it is trainable: the gut adapts to higher intake in about 28 days. That is exactly why race preparation does not start at the Nutella jar on race morning, but four weeks earlier.
Work backwards from race duration: under 1 hour, eating a lot achieves nothing — small amounts or a mouth rinse with a carb drink already deliver the proven performance benefit.
For 2–3 hours the target is about 60 g per hour, because the body cannot oxidise more from a single source — the limit of around 1 g per minute adds up to exactly those 60 g in an hour. Only beyond roughly 2.5 hours is the maximum worth it: up to 90 g per hour, but then strictly as a multiple-transporter strategy.
Write your target down as grams per lap, not as a vague "eat regularly".
Why glucose plus fructose? Because they use different transporters in the gut: the 2:1 combination lifts the oxidation rate to up to 1.26 g per minute — around 75 percent more than a single source manages.
In an MTB field study over a roughly 141-minute race, a maltodextrin:fructose intake of about 95 g per hour cut race time by 1.8 percent and reduced stomach cramps — to be read as a supplementary field finding. Read your gels' ingredient list: if it only says maltodextrin, 60 g per hour is the ceiling.
Your gut's absorption capacity is not fate: around 28 days of increased carbohydrate intake raise exogenous oxidation via upregulation of the transporters.
In practice: from four weeks before your target race, rehearse your race intake in every hard session — same products, same amount, same frequency as on race day. This is also your insurance against the most common race-day drama: 5–47 percent of riders report gastrointestinal symptoms after events.
Nothing new gets tested on race day. Nothing.
A plan you cannot recall at 180 bpm is not a plan. Schedule your fueling per lap: in XCO, around 27 percent of the time is spent not pedalling — those descending and rolling sections are your eating and drinking windows, not the climb and not the technical section.
Tape your gel timings as a strip on the top tube, distribute bottles in the feed zone, and eat from the start, not from kilometre 30: the stomach absorbs better under load when fed continuously instead of in panicked bursts — which you rehearsed in gut training.
Ambient temperatures above 20 °C are significantly associated with more injuries in MTB racing — heat does not just make you slow, it makes you error-prone.
In warm conditions, consciously adjust fluid intake and pace, pre-cool before the start (shade, a cold bottle on the neck) and plan more fluid per lap than you needed in spring training. Sweat loss is highly individual — test your drinking volumes in hot training sessions before the race tests them for you.
Gastrointestinal trouble in a race is more than annoying: cramps and nausea cost concentration — and losing concentration in technical terrain is a crash risk.
Work your way up to high intake amounts gradually and stay below them if your system rebels: 60 g per hour well tolerated beats 90 g per hour with a gag reflex. In heat, double caution applies: drink more, cool earlier, control your pace. And no experiment — neither new gels nor new caffeine doses — has its premiere in a race.
Convert your fueling into "units per lap" instead of grams per hour: in a 90-minute race with six laps and a 60 g target, that might be one 25 g gel every one and a half laps plus a bottle of mix.
Under race stress you can recall "every second lap at the feed-zone exit" — you cannot recall "25 grams every 22 minutes". The best plan is the one that still works at 180 bpm.
Beyond roughly 2.5 hours of racing: up to 90 g per hour (roughly three gels), strictly from glucose:fructose at a 2:1 ratio — only that pushes oxidation to up to 1.26 g per minute. An MTB field study with around 95 g per hour showed 1.8 percent faster race times and fewer stomach cramps. Prerequisite: rehearsed in training beforehand.
Yes — and it demonstrably works: around 28 days of increased carbohydrate intake raise absorption capacity via upregulation of the gut transporters. Rehearse your race intake from four weeks out in every hard session with exactly the race-day products and amounts. Improvisation backfires: up to 47 percent of riders report gastrointestinal symptoms after events.
Staggered by duration: up to 1 hour little to nothing, 2–3 hours around 60 g of carbohydrate per hour from gels, bars or drink, beyond that up to 90 g per hour from the 2:1 glucose:fructose mix. Drink to thirst plus a heat allowance; above 20 °C plan more generously. Eat in rolling sections, not in technical ones.
No. Under one hour, substantial eating brings no proven benefit — small amounts or even a pure carbohydrate mouth rinse are enough for the measurable performance effect. Save the gels for long sessions and rather use short loops to practise drinking from the bottle on rough ground.