Colfax Marathon: Pacing & Race-Day Strategy
Denver’s only marathon — flat and fast on paper, but run a mile above sea level.
- Where:
- Denver, Colorado
- When:
- May
- Course:
- Flat · high altitude · loop
- Best run as:
- Even pace
Course & elevation
Colfax is essentially flat, with only gentle rolling grade through the city and barely any net change. The catch is altitude: the entire course sits around 5,300 feet, where the thinner air makes any pace feel noticeably harder. It’s a flat, runnable layout that the elevation — not the terrain — defines.
Key moments
- Mile 0 & 26.2Start and finish in City Park near Ferril Lake.
- Mile 6.5Run through the Empower Field at Mile High stadium — a signature stretch.
- Mile 7–10Flat loop past Sloan’s Lake on the west side.
- Mile 20Second pass by the stadium before the trail run-in to City Park.
Pacing strategy
Respect the altitude — at 5,300 feet there’s roughly 17% less oxygen, so set goal pace honestly rather than chasing a sea-level PR. The terrain is flat enough for even pacing; run the early miles conservatively and let the thin air, not the course, be the limiter.
Plan your mile splits
Enter your goal time to get a mile-by-mile pacing band for Colfax Marathon. The even pace option is pre-selected to suit this course.
| Mile | Pace | Elapsed |
|---|---|---|
| 1 | 9:09/mi | 9:09 |
| 2 | 9:09/mi | 18:18 |
| 3 | 9:09/mi | 27:28 |
| 4 | 9:09/mi | 36:37 |
| 5 | 9:09/mi | 45:46 |
| 6 | 9:09/mi | 54:55 |
| 7 | 9:09/mi | 1:04:05 |
| 8 | 9:09/mi | 1:13:14 |
| 9 | 9:09/mi | 1:22:23 |
| 10 | 9:09/mi | 1:31:32 |
| 11 | 9:09/mi | 1:40:41 |
| 12 | 9:09/mi | 1:49:51 |
| 13 | 9:09/mi | 1:59:00 |
| 14 | 9:09/mi | 2:08:09 |
| 15 | 9:09/mi | 2:17:18 |
| 16 | 9:09/mi | 2:26:28 |
| 17 | 9:09/mi | 2:35:37 |
| 18 | 9:09/mi | 2:44:46 |
| 19 | 9:09/mi | 2:53:55 |
| 20 | 9:09/mi | 3:03:05 |
| 21 | 9:09/mi | 3:12:14 |
| 22 | 9:09/mi | 3:21:23 |
| 23 | 9:09/mi | 3:30:32 |
| 24 | 9:09/mi | 3:39:41 |
| 25 | 9:09/mi | 3:48:51 |
| 26 | 9:09/mi | 3:58:00 |
| 26.22 | 9:09/mi | 4:00:00 |
Fueling & hydration
Aid stations roughly every 1.5–2 miles with water and sports drink. Altitude and dry Colorado air accelerate dehydration — drink early and consistently, and keep electrolytes coming.
Weather
Mid-May in Denver is usually cool at the start (around 40s°F) warming into the 60s, with strong high-altitude sun and typical spring variability.
Train for Colfax Marathon
Build a free, personalized marathon plan that progresses you safely to race day — with paces tuned to your goal.
Create your free plan