If you've ever hit a wall at hour 3 of a long ride, legs suddenly refusing to work, vision narrowing, brain fogging, you bonked. And the cause was almost certainly that you didn't eat enough early enough.
The rules
Start early. Eat within the first 30 minutes of any ride over 60 minutes. Don't wait until you're hungry. By then, your glycogen is already depleted and catching up is much harder than staying ahead.
Eat consistently. Every 20-30 minutes, take something in. Small, frequent amounts beat one big bolus that sits in your stomach.
Practice in training. Your gut needs to be trained to absorb carbs during exercise. Never debut a fueling strategy on race day.
Targets by duration
Under 60 minutes
Water only. Your glycogen stores handle this fine, even for hard sessions.
60-90 minutes
30-60g carbs per hour. One gel (25-30g), half a bar (20-30g), or 500ml of sports drink (30-40g).
90 minutes to 3 hours
60-90g carbs per hour. This is where most riders need to step up. At rates above 60g/hr, you need multiple carbohydrate sources. Your gut can only absorb about 60g/hr of glucose through one transport pathway. Adding fructose activates a second pathway, pushing total absorption to 90g+.
Look for products with a 2:1 or 1:0.8 glucose-to-fructose ratio. Most modern sports nutrition products are formulated this way.
Over 3 hours
80-120g carbs per hour. This is gran fondo and stage race territory. You need a trained gut and a mix of gels, bars, real food, and sports drink.
Training your gut
You can't jump from 30g/hr to 90g/hr overnight. Your gut has to adapt.
- Week 1-2: 40-50g/hr on long rides
- Week 3-4: 60-70g/hr
- Week 5-6: 80-90g/hr
- Week 7+: Push toward 100-120g/hr if needed
If you get bloating, cramps, or nausea, back off 10-20g/hr and build up more gradually. Liquid calories (sports drink) are usually easier to tolerate than solid food during hard efforts.
Caffeine
Proven ergogenic aid. 3-6mg per kg body weight, taken 30-60 minutes before exercise, improves power output, reduces perceived effort, and delays fatigue. Many gels include 25-50mg. For a 75 kg rider, total target is 225-450mg spread across the ride.
If you use caffeine in training, you'll need it in racing for the same effect. Tolerance builds fast.
The biggest mistake
Not eating enough. Research keeps showing that amateur cyclists underfuel during long rides. They consume 30-40g/hr when they should be doing 60-90g/hr. The result is a preventable bonk that turns the last hour of a beautiful ride into a death march.
You spent months building fitness. Don't let it go to waste because you skipped a gel at minute 45. More nutrition guidance in the complete cycling nutrition guide.