Ironman vs 70.3: How the Bike Leg Differs
An Ironman's bike leg is 180 km and a 70.3's is 90 km, and the difference is more than double the distance. The full distance is ridden at a lower share of FTP — around 65–75 % against 75–82 % — because a marathon follows it instead of a half marathon; its long training rides reach 4.5–6 hours against 2.5–3.5; and fuelling becomes the deciding skill. Cycloscape has preparation pages for 43 Ironman and 130 70.3 races.
The two bike legs side by side
The same sport, two different days on the bike:
| Ironman (full) | IRONMAN 70.3 | |
|---|---|---|
| Swim · bike · run | 3.8 km · 180 km · 42.2 km | 1.9 km · 90 km · 21.1 km |
| Typical bike time | 5.5–7.5 hours | 2.5–3.5 hours |
| Effort, share of FTP | About 65–75 % | About 75–82 % |
| Longest training ride | 4.5–6 hours | 2.5–3.5 hours |
| The deciding skill | Pacing and fuelling for hours | Holding a strong, steady effort |
Which to choose
A 70.3 is the usual step before a full Ironman: the training fits around a working week more easily (a typical build peaks at 8–12 hours a week, against 12–18 for a full), and race day is short enough to learn pacing and fuelling without paying for every mistake for hours.
A full Ironman is a different event: the bike leg alone is longer than most people's longest ride, and the preparation is built around making that ride routine.
Find a race
Every race has its own page with its date, its bike course and how to prepare it:
Frequently asked
How long is the bike leg of an Ironman and a 70.3?
180 km (112 miles) in an Ironman and 90 km (56 miles) in a 70.3.
Should I do a 70.3 before a full Ironman?
It is the usual path: a 70.3 teaches pacing, fuelling and transitions on a day short enough to learn from, with less training time.
Why is the Ironman bike ridden easier than the 70.3 bike?
Because it is twice as long and followed by a full marathon: the effort has to be sustainable for longer, so it is a lower share of FTP.