Ironman Boulder 70.3: the bike course and how to prepare it
- Distance
- 90.5 km
- Climbing
- 683 m
- Highest point
- 1,736 m
- Categorised climbs
- 2 · up to 3 %
- Shape
- Loop
Measured on the course you ride in Cycloscape. The organiser's own figures are below.
Elevation profile
1,542–1,736 m · 2 categorised climbsIronman Boulder 70.3 is an IRONMAN 70.3 triathlon — 1.9 km swim, 90 km bike, 21.1 km run — in Boulder, United States. The next edition is on 12 June 2027, according to IRONMAN. Two loops start at the Boulder Reservoir, along the Diagonal Highway towards the foothills, with short rollers, then a fast downhill section back on rural roads.
Ironman Boulder 70.3 at a glance
- Where
- Boulder, United States
- Official race page
- ironman.com ↗
- Next edition
- 12 June 2027
- Distances
- 1.9 km swim · 90 km bike · 21.1 km run
- Bike course
- 90 km
- Terrain
- Rolling to flat
- Facts checked
- 5 November 2026, against the sources below
Full preparation and course training require Event Coach Pro.
Ride the real course on your trainer. The route of Ironman Boulder 70.3, 90 km, as a 3D world, with your trainer following its gradients — any day, and as part of your Event Coach plan. Part of Cycloscape Pro.
The bike course
Ironman Boulder 70.3 is a 70.3 (half-distance) triathlon: 1.9 km swim, 90 km bike, 21.1 km run.
| Leg | Distance | Climbing |
|---|---|---|
| Bike leg (two loops) | 90 km | — |
What the bike leg asks of you
The course sits at about 1,600 m: efforts feel harder than at sea level, so start below your usual power.
How to prepare the bike leg
The general shape of a good bike preparation, which Event Coach turns into a plan for your fitness, time and date:
- Train sustained tempo: the 90 km of Ironman Boulder 70.3 are ridden around three-quarters to four-fifths of FTP, hard enough to race and controlled enough to run a half marathon after.
- Ride your long sessions in the position you will race in, and practise eating and drinking on the bike: on race day you fuel the run on the bike.
- Add short runs straight after some long rides (brick sessions), planned around your bike training — Event Coach prepares the bike; your swim and run are yours to fit around it.
Pacing mistakes to avoid
The mistakes that cost triathletes the most on the bike:
- Riding the first hour of Ironman Boulder 70.3 on adrenaline: the watts you spend early come back as minutes lost on the run.
- Surging on every hill and every overtake instead of holding an even power.
- Under-eating on the bike: the energy for the run has to go in before you get off it.
Prepare the bike leg of Ironman Boulder 70.3 with Cycloscape
Tell Event Coach you are racing Ironman Boulder 70.3 and it builds the bike side of your preparation towards 12 June 2027: structured workouts held by your trainer in ERG, pacing for the course and Performance Lab to see whether the work is landing. Swimming and running are not part of the plan. Full preparation and course training require Event Coach Pro.
Frequently asked
When is Ironman Boulder 70.3 2027?
On Saturday, 12 June 2027, according to the organiser.
How long is the bike course of Ironman Boulder 70.3?
90 km. The bike leg as IRONMAN describes its course (two loops).
Does Event Coach plan my swimming and running?
No. It prepares the bike leg — workouts, pacing and the course — and tells you where to fit short runs after long rides. Plan your swim and run with your own coach or programme.
Can I ride the bike course of Ironman Boulder 70.3 in Cycloscape?
Yes, inside Event Coach with Cycloscape Pro: the bike course is ridden on your trainer as part of your preparation. It is never a free or standalone ride.