Busselton is the fastest Ironman course in Australia and the least forgiving on nutrition. Flat means constant pedalling, constant pedalling means constant carbohydrate burn, and there are no descents to hide a missed feed.
Fast courses also tempt athletes into riding above their trained effort because the numbers look easy early. The marathon is where that conversation finishes, and how well you fuelled the previous six hours decides the tone of it.
What the race demands
Distance
3.8km swim, 180km bike, 42.2km run
Conditions
Flat, exposed, often windy December race in Western Australia
Main risk
Continuous power output with no recovery windows on the bike
Second risk
Late-year heat combined with wind hiding sweat losses
Carbohydrate and sodium targets
- Bike leg: 80 to 120g of carbohydrate per hour from a dual-carb source if your gut is trained for it
- Run leg: 60 to 90g of carbohydrate per hour in small frequent doses
- Sodium: 700 to 1,200mg per hour, higher again for salty and heavy sweaters
- Fluid: guided by your measured sweat rate, tracked hour by hour
HYDRAX CORE delivers 85g of dual-carb fuel and 980mg of sodium per serve, so hitting the numbers above is arithmetic rather than guesswork. HYDRAX PRIMER covers the pre-race window with 29g of carbohydrate and 1,313mg of sodium. Run the free fuelling strategy tool to convert these ranges into your own per-hour numbers.
Rehearse the plan in training, then race it. Order now, ships Australia-wide.
Race week and race day timeline
3 days out
Carb load toward 8 to 12g per kg per day and cut fibre well before race morning.
Race morning, 3 hours out
Rehearsed carbohydrate breakfast at 2g per kg with sodium in your fluid.
25 to 40 minutes pre-swim
One serve of PRIMER for 29g of carbohydrate and 1,313mg of sodium before a 3.8km fuelling blackout.
Bike, 180km
Set a 15 minute alarm and fuel to it. There are no descents on this course to create a natural feeding rhythm.
Run, 42.2km
Small doses every aid station, and keep sodium going even if the wind makes you feel dry rather than sweaty.
Frequently asked questions
How do I fuel a flat Ironman bike course?
Flat courses remove the natural feeding windows created by descents, so fuel on a timer every 15 to 20 minutes. Power output stays constant, so carbohydrate demand stays constant too.
How much sodium at IRONMAN Western Australia?
Plan 700 to 1,200mg per hour for most athletes. Wind dries sweat quickly and makes losses feel smaller than they are, so use a measured sweat rate rather than sensation.
Can I take 120g of carbs per hour?
Only if you have trained for it. High rates require dual-carb fuel and repeated rehearsal in long sessions. An athlete absorbing 90g per hour comfortably will beat one attempting 120g per hour and vomiting at 140km.
What should I drink during an Ironman?
A dual-carb drink mix with meaningful sodium so carbohydrate, fluid and electrolytes arrive together, supplemented with plain water to adjust concentration in heat.
Keep reading
- Ironman 70.3 nutrition guide
- Full Ironman nutrition guide
- Carbs per hour for Ironman
- Triathlon time calculator
- Measure your sweat rate
- Shop the HYDRAX kit
Disclaimer: This page is general information for healthy adult athletes and is not medical, dietetic or coaching advice. Individual carbohydrate, fluid and sodium requirements vary with body weight, sweat rate, conditions and health status. Speak with your doctor, sports physician or an accredited sports dietitian before changing your nutrition or supplement routine, rehearse any fuelling plan in training before race day, and always follow the directions and warnings on the product label.