After coaching athletes through dozens of Ironman races, the same mistakes appear over and over. They are not obscure or complicated. They are fundamental errors in pacing, nutrition, and bike execution that cost age groupers significant time - and all three are entirely fixable.
1. Being Afraid of Race Pace
This is the most widespread issue I see. Athletes arrive at their Ironman having never spent meaningful time at race pace because it feels "too easy" in training. They associate productive training with suffering, so when a session at Ironman pace feels comfortable, they assume it is not fast enough.
Ironman pace should feel easy. That is the entire point. You are sustaining effort for eight to seventeen hours. If it feels hard in the first hour, you are going too fast.
The fix is straightforward: in the lead-up to your race, do up to 40 percent of your weekly volume at Ironman race pace. Get comfortable with how it feels. Learn to trust that this effort, sustained over the full distance, produces a fast time. Do not let the perceived ease of the effort trick you into going harder.
2. Trying to Spread Fuelling Evenly
The conventional approach to Ironman nutrition is to calculate a target hourly intake and apply it evenly across the entire race. Eighty grams of carbohydrate per hour from start to finish. It sounds logical, but it ignores how the body actually works during a race of this duration.
A better approach is to front-load your nutrition on the bike. Your gut functions better earlier in the race when intensity is lower and blood flow to the digestive system is less compromised. By the time you reach the run, absorption becomes harder and gastrointestinal distress becomes more likely.
Front-load the bike, protect the run. Taking in 100 grams per hour on the bike and 60 on the run beats a flat 80 across both.
For example, if your overall target is around 80 grams per hour, consider pushing to 100 grams per hour on the bike and reducing to 60 grams per hour on the run. You take in the same total calories but in a pattern that works with your physiology rather than against it.
3. Over-Biking
The Ironman bike is not a time trial. It is the setup for a marathon. Every extra watt you push on the bike is borrowed from your legs on the run, and the exchange rate is punishing.
For age-group athletes, a reasonable bike effort sits at 65 to 75 percent of FTP. Yes, professional athletes push 80 percent or higher, but they are physiologically specialised machines with years of adaptation to sustaining high outputs over long durations. Trying to replicate their intensity percentages is a recipe for a death march marathon. Make sure you actually know your real FTP before setting these targets.
The athletes who run well off the bike in Ironman are almost always the ones who showed restraint during the 180 kilometres before it. They arrive at T2 with legs that still have something to give, while the riders who chased a fast bike split are walking aid stations by the halfway mark of the marathon.
If you want to go faster in Ironman, the answer is almost never to ride harder. It is to ride smarter and run better.