Race Day at 70.3 Boulder: Timeline, Common Mistakes, and Plan B

The Days Before

The first decision is when to arrive. At ~1,620 m of altitude, if you're coming from sea level you have two sensible options: arrive very early to acclimate, or as late as possible to limit the acute impact. Arriving "in between," three or four days out, is often the worst window. In the days before, get in at least one adaptation swim in the Reservoir or in cold water: the stated average is 17°C and in June expect 15-18°C. Use it to scope out the entry from the east boat ramp too. If you can, drive or ride a section of the bike course to get a feel for the rollers.

Race Morning

Cool start: lows are around 13°C. Dress in layers for the wait and bring flip-flops. Parking in 2022 was close to transition, but arrive early anyway: the racks are tight and setting up your spot without rushing is worth gold. Sunscreen before putting on your wetsuit: the bike and run are fully exposed to the Colorado sun.

The Swim

One counterclockwise 1.9 km loop, rolling start. With a stated average of 17°C, wetsuits are almost certainly allowed; in 2022 the water was 23.6°C and the race was still wetsuit legal. Warm up properly before the start: jumping into cold water cold is the best way to go into oxygen debt in the first 200 meters. The water is murky but pleasant, according to reports.

Bike and Run: The Common Thread

The theme of the day is twofold: altitude and rising heat. You start cool, you finish with possible 33°C temps, and in 2022 the heat index hit 35-38°C. So: conservative watts on the two bike loops, no spikes on the kickers, sodium and fluids from the first kilometers. On the run, two loops on exposed gravel: first loop under control, ice and sponges at every aid station, then decide whether to push.

Common Mistakes

• Starting with sea-level watts and paces: they don't hold at altitude.
• Putting off hydration until the run: cramps in 2022 were hitting from the first mile.
• Tall, unstable super shoes never tested on gravel.
• Ignoring that after the finish line there's a walk back to transition for your gear: no flip-flops, no mercy.

Plan B

Prepare for three scenarios. Extreme heat: cut your pace further, double up on cooling at aid stations, and accept a slower time; finishing well beats blowing up. Modified swim: in 2022, high bacteria levels led to changes to the swim leg; listen to the announcements and stay mentally flexible about the start format. Wind on the course: the bike and run are exposed, so plan by effort, not by speed or pace.

Final Checklist

• Cold-water adaptation swim done.
• Power and pace targets recalibrated for altitude and heat, written down and tested.
• Layers for the cool start, sunscreen, sunglasses.
• Run aid station plan memorized: ice, sponges, always drink.
• Flip-flops and drinks for post-race.
• Check official communications in the morning: wetsuit status, water, any course changes.