← All races
🇺🇸

Boulder 70.3

Boulder, CO · USA · June · 70.3

Altitude is the hidden tax — pace and fuel as if everything is a notch harder.

🏊 Swim

1.9 km

Calm reservoir swim — but altitude shortens your breath.

Strategy: Start easy; at altitude your usual effort costs more oxygen. Build into it.

🚴 Bike

90 km · 650 m ↑

Rolling foothills with thin air.

Strategy: Power feels normal but heart rate runs high. Trust power, not feel, and hydrate hard in dry air.

🏃 Run

21.1 km

Rolling reservoir paths at altitude.

Strategy: Add time to your flatland run expectation — the thin air makes the back half costlier.

Course & conditions

Bike climbing
650 m
Likely temp
24°C
Water
18–22°C
Wetsuit: likely legal / recommended
Climate: High altitude, strong sun, dry air.

Cutoffs

GateCutoff (from your start)
Swim — out of the water1:10:00
Off the bike5:30:00
Overall finish8:30:00
Template cutoffs updated 2026-06-22 basis: rolling Official Athlete Guide ↗

Standard 70.3 cutoff structure shown as a planning template — most 70.3s allow ~8:30 overall from your rolling start, with a swim cutoff near 1:10 and a bike cutoff near 5:30. Mid-bike and mid-run cutoffs vary. Always confirm the exact gates and clock basis in this event’s Athlete Guide for your race year.

Targets by level

Finish-first

Beat every cutoff with margin. Swim relaxed, ride well within yourself, walk-run the climbs, and never stop fuelling.

Sub-6 / strong age-grouper

Hold steady race power on the bike, protect the run, and execute transitions cleanly. The run is won by what you did NOT do on the bike.

Competitive age-group

Sharp swim, disciplined high-end bike to your durability, and a negative-split run. Every transition second counts.

First-timer risks

  • Pacing to sea-level numbers and fading in thin air.
  • Dehydration in dry, sunny conditions.

Packing & prep

  • Arrive early to acclimate if you live at sea level.
  • Strong sun protection and extra fluid.

Race-morning timeline

−3:00 h Wake, main breakfast, sip fluid. Familiar food only.
−1:30 h Arrive, body-mark, set up transition, pump tyres, rack bike.
−1:00 h Top-up carbs + fluid. Wetsuit half-on, short warm-up.
−15 min Optional gel, get to the swim corral, find your seed pace group.
Gun Start controlled — the first 300 m of the swim is not the race.

A generic template — adjust to the event’s actual transition close and start times in the Athlete Guide.

Now make it personal

Turn this course into your own finish-time bands, cutoff check and fueling plan in 60 seconds.

Build my Race Blueprint →
🏊
Add TriPB to your home screen
Your race plan, one tap away — works offline on race morning.