Caffeine on a gran fondo: how much, and when?

The short answer: 3 to 6 mg of caffeine per kilogram of body weight reliably helps endurance performance. On a long ride, part of it taken later, when fatigue sets in, may help more than all of it before the start. Keep single doses to 200 mg and the day to 400 mg.

How much?

The International Society of Sports Nutrition’s position stand puts the effective dose at 3 to 6 mg per kilogram, and the minimum may be as low as 2 mg per kilogram ¹. For a 70 kg rider that is about 210 to 420 mg. Very high doses, around 9 mg per kilogram, bring many side effects and are not needed for a benefit ¹.

Aerobic endurance is where caffeine helps most consistently, but how much differs from rider to rider ¹.

When?

The most common timing in studies is 60 minutes before exercise. After swallowing, caffeine in the blood peaks somewhere between 30 and 120 minutes, and it takes 4 to 6 hours for half of it to clear ¹. That long half-life is why the exact minute does not matter much.

In long events, caffeine taken later in the race, closer to when you get tired, may help more than caffeine taken beforehand; low doses taken late compared well with higher doses taken an hour before the start ¹. Caffeine gum is absorbed through the cheek and acts faster than a capsule ¹, which helps if you are late with your dose.

Safe limits

The European Food Safety Authority considers single doses up to 200 mg, and up to 400 mg over a day, safe for healthy adults, including during intense exercise ². The limits are different in pregnancy. If you have a heart condition or take medication, ask your doctor first.

Try it in training

Because responses vary, try your dose and timing on training rides before race day ¹.

How the FondoLab planner handles it

The planner sets a dose from your weight and sensitivity: 3, 4.5 or 6 mg per kilogram. On rides of three hours or more it splits it into an early dose about 45 minutes before the start and a finishing dose about 75 minutes before the finish, collected at the last feed station before then. Each dose is capped at 200 mg and the ride at 400 mg. The 45 and 75 minutes are FondoLab defaults, not numbers from a study.