WHO THIS IS FOR
IS THIS YOU?
The rider who always cramps or fades in summer
If your performance in heat is worse than your winter rides, poor hydration is likely part of the explanation.
The gran fondo rider heading to a warm-weather event
International sportives in Italy, Spain, or southern France reward riders who've planned hydration properly. The finish time difference is real.
THE ROADMAN VIEW
The Roadman view
Hydration in heat is one of those areas where the advice sounds simple and the execution falls apart in practice. Anthony has spoken to Sam Impey and David Dunne on the podcast — both World Tour nutritionists — and the message is consistent: the problem isn't that riders don't know they should drink, it's that thirst is a useless signal in hot conditions. By the time you're thirsty, you're already 1–2% dehydrated, and at 2% dehydration endurance performance has measurably dropped.
The electrolyte piece is the part most amateur riders miss. Drinking plain water at high volumes over a hot ride dilutes blood sodium — hyponatraemia is more common in endurance sport than most people realise, and in serious cases it's a medical emergency. The fix is simple: add sodium from an electrolyte tab, a sports drink, or salty real food. World Tour riders don't drink plain water on hot stages for a reason.
The pre-ride loading is the piece that makes the biggest difference per unit of effort. Getting 500–750ml of fluid and some sodium in before you even clip in starts you ahead rather than behind. You can't replicate this once you're on the road in 35°C heat — the gastrointestinal system doesn't absorb fast enough in those conditions to fully recover from starting dehydrated.
EXPERT EVIDENCE
WHAT THE EXPERTS SAY
- Sam ImpeyWorld Tour nutritionist
Elite cyclists in hot conditions lose 1–2 litres of sweat per hour with significant sodium content. The pro approach is three-phase hydration: pre-load, on-bike drinking scheduled rather than thirst-driven, and immediate post-ride replacement. Electrolytes throughout are non-negotiable — plain water at high intake is a performance and safety problem.
Hear it: Why Pros' 120g Carb Rule Fails Amateurs | Roadman Cycling - David DunnePerformance nutritionist, INEOS Grenadiers, EF Education, Uno-X
Pre-ride sodium loading is one of the most underused tactics in amateur cycling. Sodium draws fluid into the vascular space, expanding plasma volume before exercise starts. A pinch of salt in your pre-ride bottle or a sodium-rich meal 2–3 hours before costs nothing and materially improves hot-weather performance.
Hear it: World Tour Nutritionist - “We Got Weight Loss Wrong”
PRACTICAL APPLICATION
DO THIS WEEK
Pre-load 2 hours before the ride
Drink 500–750ml of fluid containing sodium — an electrolyte tab in water, a sports drink, or a sodium-rich meal alongside water. This pre-loads plasma volume and starts you hydrated rather than neutral.
Drink on a schedule, not on thirst
Set a reminder on your head unit to drink every 10–15 minutes. Target 500ml per hour in mild heat, up to 1 litre per hour at 30°C+ or race intensity. Include electrolytes — one electrolyte tab or sodium-containing drink per bottle.
Weigh yourself before and after
Each kilogram of body weight lost during a ride equals approximately 1 litre of fluid deficit. Do this after two or three hot rides to understand your personal sweat rate, then scale your on-bike intake to match.
COMMON MISTAKES
WHAT CYCLISTS GET WRONG
MISTAKEStarting a hot ride without pre-loading fluid.
FIXDrink 500–750ml with electrolytes in the 2 hours before. You cannot catch up once you're dehydrated and working hard in heat.
MISTAKEDrinking only plain water on hot rides over 90 minutes.
FIXAdd sodium to at least every second bottle. Plain water at high intake dilutes blood sodium and can cause cramping or hyponatraemia. Electrolyte tabs, sports drinks, or salty food all work.
MISTAKEDrinking so much that the gut rebels.
FIXAbsorptive capacity in heat is roughly 500–800ml per hour. Trying to drink 1.5 litres an hour can cause GI distress. Scale intake to a rate the gut tolerates and accept some fluid deficit on very hot rides — controlled dehydration beats nausea.
FAQ
FREQUENTLY ASKED QUESTIONS
How much water should I drink before a hot cycling race?
What are the signs of dehydration on the bike?
Are sports drinks better than water for hot rides?
Does caffeine count against hydration?
What should I drink immediately after a hot ride?
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