IRONMAN 70.3 Boulder 2027
A reservoir swim, two rolling loops under the Flatirons, and a two-lap run on hard-packed dirt. All of it at 1,600m of altitude.
2027 edition completed
This record covers the 12 June 2027 edition of IRONMAN 70.3 Boulder in Boulder, Colorado, USA, with a 1.9 km swim, a 90.1 km bike and a 21.1 km run. This date belongs to a completed edition. The course record remains available. Course descriptions and coaching notes are archived context for this edition. Check the organiser for a future edition once its date and entry details are published.
34 weeks to race day: base season
Plenty of runway. This far out, the win is a boring, consistent base rhythm: aerobic volume, strength, technique. The structured block starts closer in; what you do now decides how high it can climb.
Building for this one? 70.3 training plan covers the sessions, the weekly shape and how the block is paced. The R.A.C.E. Framework explains why it is built that way.
Build my complete road.
Commit to the date and the work gets a shape: your countdown starts, the emails arrive in step with your build, and the app anchors a recovery-led block so the final week lands exactly on race day.
One confirmation email, then the road begins. Registering for the race itself stays with the organiser.
“Boulder sits at about 1,600 metres and altitude is the whole story. Arrive either three days out or three weeks out, never one week out, and take your goal power down by five to eight percent whatever the profile says.”
The race
The course
No course maps for this race. IRONMAN publishes no downloadable route for any leg of this race, so there is nothing to draw a course map from. Everything below comes from the official course page, checked on the date at the foot of this section.
One counterclockwise loop, entering at the east boat ramp and exiting at the west before heading to transition.
Two loops from the reservoir onto the Diagonal Highway towards the Foothills Highway, short rollers, then right onto rural Hygiene Road and a fast downhill run to 63rd Street before rejoining the Diagonal for the second lap.
Two counterclockwise loops around the reservoir, part trail, part hard-packed dirt road on Monarch and 55th, with downhill rollers. This is the ground the best distance runners in America train on daily.
Not yet confirmed for this edition: bike elevation gain, transition locations, cut-off times, water temperature history. We publish these only once they are on the official course page, so check there before you pace off anything here.
Course details verified against the official IRONMAN 70.3 Boulder course page on 14 August 2026. Courses change; the official page is always the last word.
Questions, answered
When is IRONMAN 70.3 Boulder 2027?
What distances can I race at IRONMAN 70.3 Boulder?
How hard is the course?
What is the swim like?
How long do I need to train for it?
How do I enter?
Read before you race
Half Ironman Recovery Time: A Practical Return
How Much Harder Is a Full IRONMAN Than a 70.3?
IRONMAN 70.3 Tallinn Training Guide
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Photograph of Boulder, Colorado, USA: Jeffrey Beall, CC BY 4.0, via Wikimedia Commons. Not official race photography.
This listing is for information only. Unbroken is not affiliated with, endorsed by, or sponsored by IRONMAN 70.3 Boulder or its organiser. Details are based on publicly available information; names are used descriptively to identify the event. For accurate, up-to-date information and entry, always use the official event website.