IRONMAN 70.3 Weymouth 2026: Complete Course Guide and Race Day Tips

Race Overview

IRONMAN 70.3 Weymouth takes place on 20 September 2026 and attracts around 2,800 competitors to the stunning Dorset coastline — the same venue that hosted open water swimming at the 2012 London Olympics. Here is everything you need to know about the swim, bike and run course to plan your training and race strategy.

The Swim: Weymouth Bay (1.9km)

The 1.9km swim takes place in Weymouth Bay, a naturally sheltered bay with generally calm conditions. September water temperatures typically sit at 16–18°C, meaning wetsuits are usually permitted. The swim is a single loop with a rolling wave start grouped by estimated swim time.

Distance: 1.9km (one loop)
Water temp: Approx 16–18°C in September — wetsuits typically permitted
Tip: Sight frequently — even calm bays have subtle drift. Aim for buoys early and avoid wide lines
Tip: Practice open water swimming in the months before — your first race is not the time to discover how different open water feels to a pool

The Bike: Hilly Dorset Roads (90km)

The 90km bike course is widely regarded as one of the toughest on the UK 70.3 calendar. Narrow, exposed Dorset lanes wind through the Purbeck Hills with significant climbing throughout. Do not underestimate it — athletes who go out too hard on the bike typically struggle badly on the run.

Distance: 90km
Elevation: Approximately 1,400m of climbing across the course
Key feature: Multiple sharp ascents through the Purbeck Hills requiring good climbing technique
Nutrition: Carry more than you think you need — the hills burn through glycogen faster than flat courses
Tip: Train on hilly routes in the 8–12 weeks before race day. Our 90-minute hilly outdoor ride session will help build the specific strength needed.

The Run: Weymouth Esplanade (21.1km)

The half-marathon run is a welcome contrast to the hilly bike — it is flat, fast, and atmospheric, following the Weymouth seafront promenade. The course is multiple laps, which gives you a chance to see supporters, feed off the crowd energy, and gauge your competitors. Be warned: even a flat run hurts after 90km of Dorset hills.

Distance: 21.1km
Terrain: Flat tarmac promenade — fast conditions for most athletes
Aid stations: Approximately every 2km with water, electrolytes and cola in later stages
Tip: Aim for a negative split — hold back in the first 5km and build into the second half. Most athletes go out too fast after T2.

Transitions: T1 and T2

T1: The run from swim exit to transition on the beach can be longer than expected — practise a quick wetsuit strip in training
T2: Racking is typically alphabetical — walk the transition zone the day before to memorise your rack position
September evenings cool quickly: Consider a light arm warmer for the bike if you are racing later in the day and the forecast is overcast

Race Week Tips for Weymouth 70.3

Book accommodation early — Weymouth fills fast for race week, especially guesthouses near the seafront
Recce the bike course if you can — encountering the Purbeck climbs for the first time on race day is a significant disadvantage
Transition and registration is typically held at the Weymouth Pavilion the day before — allow time for kit check and to rack your bike
The race has a 17-hour time limit — start strong and pace the bike conservatively to protect the run