IRONMAN 70.3 Knokke-Heist: Course, Route Profile & Map

Course & Elevation

The day does not start in Belgium. The swim is a single 1.9-kilometre loop in the Damse Vaart at Sluis, across the Dutch border, where T1 also sits; a shuttle carries spectators there from Knokke-Heist for ten euros. The swim cut-off is 1:10.

The bike is one 90-kilometre loop through the borderland: out of Sluis past Sint Anna ter Muiden and Retranchement in Zeeland, then on through the West Flanders polders before finishing at the De Taeye stadium in Heist. It is about as flat as a bike course can be – 96 percent of the distance sits in the level band, the elevation runs from minus one to five metres above sea level, and 90 kilometres yield 113 metres of climbing. There is no hill to hide behind.

The run leaves the stadium through the Directeur generaal Willemspark and then takes the Zeedijk: three laps of the sea-dyke promenade, barriered on both sides with crossings at every beach bar, finishing at the Evenementenstrand in Duinbergen. The overall cut-off is eight hours from the timing mat. The fourth edition, in 2026, sold out in fourteen days.

Pacing Strategy

On a course without hills the bike is one uninterrupted decision – and that is exactly the trap. Ninety-six percent flat means no recovery out of the saddle, no descent, no natural change of muscular load: you sit in the same position for ninety kilometres turning the same cadence. Set your power by the terrain rather than by the clock and you will ride too hard.

The wind decides it. Between Sluis, Retranchement and the West Flanders polders there is no shelter at all, and on the coast the wind turns through the morning. On a single loop that means one long tailwind section and an equally long headwind one – ration your effort by section rather than by average speed, or you will burn yourself into the headwind and freewheel with the tailwind.

The run is the second test of the same principle. Three laps of the Zeedijk are flat, straight and shadeless; the eight-hour cut-off is generous, but the course gives you no reason to change pace. Plan the first lap as deliberately the slowest and drink at every station – after ninety kilometres in the aero position, the second lap is where mistakes made on the bike surface.

Training plan for IRONMAN 70.3 Knokke-Heist: 12-week build

For a middle distance on this course, reckon on four and a half to eight hours depending on level; the official limit is eight hours from the timing mat, with 1:10 for the swim and 5:20 to the end of the bike. The effort is unusually uniform: a sustained aerobic one, without the anaerobic spikes a hilly 70.3 imposes.

Two things decide it and neither is the profile. First, holding an aero position for ninety kilometres with not one interruption – a question of core strength and position tolerance, not of FTP. Second, the wind, which on a flat single loop is the course's real difficulty.

So the emphasis is long steady bike sessions in race position: two- to three-hour rides entirely on the bars, ideally on flat open roads in wind, each followed by a 20- to 40-minute brick run. Add core and neck work, because nothing on this course lifts you out of the position. For the swim, open-water practice in a canal is enough – the Damse Vaart is sheltered and slow-moving, but dark and narrow, which asks for sighting without a clear view.

Conditions: early September on the Belgian-Dutch coast means 16 to 22 degrees, wind off the North Sea and a run course with not a metre of shade. Rehearse fuelling in the warmth, plan clothing for a cool canal swim and a warm dyke run, and train at least two long bike sessions in a genuine headwind – that is the condition that defines this race.