IRONMAN · IRONMAN 70.3 · Course speed

New course, new times: why a race's old results don't carry over

When a course changes, its old times stop being a guide. The site now finds every change, race by race.

By Blame the Course · · 2 min read

55of 172 qualifying races have raced more than one course

4courses at 70.3 Calgary since 2010

~20%the swing in Calgary's bike between two of them

Calgary's four courses

A third of the IRONMAN and 70.3 races have changed course at least once, and their old times don't carry over. IRONMAN 70.3 Calgary has raced four courses. The bike that played 8 to 12% faster than the median course in 2017–19 played 8 to 10% slower in 2021–22, a swing of about 20%. A shorter bike (88 km instead of 90) and a longer run came in 2023, and a new run in 2026. A 2:40 bike split on one of them says little about the next.

IRONMAN 70.3 Calgary: how the bike played each year, against the median course

Course ACourse BCourse CCourse D−10%−5%0%+5%+10%201020122014201620182020202220242026above zero: slower than the median course
faster than the median courseslower
2020 not raced; 2025's bike was shortened (a partial course) and is left out.

New venues, new swims

Some changes are a new venue: IRONMAN 70.3 Cozumel moved from Cancún in 2013. Some are a new swim: 70.3 Lapu-Lapu's new venue swam about 30% faster in its first year (one year so far: watch the next). Either way, a time from the old course is a poor guide to the new one, and a course's reputation can lag years behind the course raced now.

How the site finds a course change

The site reads each race's history and marks a new version of its course when one of three things happens: a new venue in the event's name; a leg's distance changing for good (not a one-off detour that reverts the next year); or a leg that plays faster or slower for good. Each race's course page lists its versions, and the course's speed is measured on the version raced now, so a new course isn't judged by the old one's years.

What it means for your time

When you compare your time with a race's past results, check that it was the same course. When you carry a time from one course to another, use the current version's speed. Both are on each race's course page.

Measured from IRONMAN's public results. Course and day speeds come from the athletes who raced more than one course; "typical" is the median of the same measure across races of the distance. Figures as of 3 October 2026. Blame the Course is independent and not affiliated with IRONMAN.

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