The IRONMAN Wales Bike Course: 112 Miles of Punchy Climbs That Decide Your Marathon

The big picture

Let's be clear: the bike is the heart of this race. 180 km through the Pembrokeshire countryside with roughly 2,400 m of climbing; one guide quotes over 2,500 m, other sources don't give a figure, so treat the number as a ballpark, not gospel. There's no long alpine-style climb: there are dozens of punchy climbs, many of them steep, repeated all day long. Segment profiles show the same climbs about 90 km apart, so it's almost certainly a two-lap course. Check the official 2027 map before you plan anything.

The climbs that matter

Two names come up in every race report and course guide:

• Cross Hands: around 4 km at a 5-7% average gradient. It's the "long" climb of the day. Stay seated here, ride at a steady pace, below threshold. This is the right place to eat beforehand and catch your breath.
• Wisemans Bridge up to Saundersfoot: short but brutal, with pitches around 22%. The crowd is loud here and the temptation to attack is strong. Resist it: 300 W on a 20% ramp gets paid back at mile 18 of the marathon.

In between, dozens of back-to-back kickers. The course never leaves you alone: you're either climbing, descending or surging.

The descents: the real risk

The descents are steep and often end in a corner. The road surface is generally good but slippery in the rain, and athletes have reported some rough sections. In mid-September on the Irish Sea, rain is a realistic scenario, not a remote possibility. Three practical takeaways:

1. Reliable brakes: fresh pads, system checked over. If you're on discs, that's an advantage here. 2. Recon: if you can, ride or drive the key sections in the days before. Knowing where a descent ends changes everything. 3. Tyres: wider tyres and don't max out the pressure. This is not the day for 130 psi.

Gearing and position

Fit easy gearing: a compact up front and an 11-34 out back is the sensible setup. If you hit Wisemans Bridge with a 36x28 as your easiest gear, you'll remember it for a long time. The aero position only matters on the fast sections: on this course you'll spend a lot of time on the hoods, climbing and descending. If you're choosing between an extreme TT setup and something more rideable, handling wins here.

Pacing: the rule that saves your marathon

The trap on this leg is stacking up dozens of above-threshold power spikes, one for every kicker. Individually they seem like nothing; added up, they empty your legs. The plan:

• Set a power cap (or RPE cap) for the ramps and never exceed it, not even when the crowd is screaming.
• Use the descents and fast sections to recover and eat: aim for 80-90 g/h of carbs, tested in training.
• On the second lap you already know the climbs: use that knowledge to pace, not to push harder.

How to train for it

Between now and race day, two priorities:

• Repeated short, steep efforts: sets of 1-3 minute ramps above 10%, staying seated when possible, to build specific strength.
• 4-5 km climbs at steady pace: they simulate Cross Hands and teach you not to overcook it.

Add long rides on rolling terrain with the same bike and gearing you'll race on. And at least one long ride in the rain: in Tenby you may genuinely need it.

What to do now: check your cassette (11-34 if you don't have one), order new brake pads and schedule a block of hill strength work. The official 2027 map, as soon as it drops, needs to be studied corner by corner.