A Simple 70.3 Pacing Framework for Age-Group Athletes
Most athletes I talk to after a 70.3 say the same thing: the run fell apart. Almost every time, the mistake happened on the bike — two hours earlier.
This it's not a talent problem or a fitness problem. It's a pacing problem. And pacing is the one part of race day you can actually control.
Here's the framework I give the athletes I coach when they're building toward their first — or their fastest — 70.3.
The Bike Is Where 70.3s Are Won and Lost
Not the swim. The swim is short, it's early, and it's over before your body has really warmed up. Not the run either — the run is just where the bill from the bike gets paid.
The honest truth about the 70.3 bike: you are not racing it. You are managing it. Every watt you overcook in the first hour is a minute — sometimes more — you pay back somewhere between kilometre 12 and kilometre 18 of the run.
The problem is that the bike doesn't tell you you're overcooking it. It feels fine. That's exactly what makes it dangerous.
Pacing Without a Power Meter — The RPE Framework
Most age-group athletes don't have a power meter, and that's fine. You don't need one to pace a 70.3 bike leg intelligently. You need an honest read on effort.
Here's the scale I use, on a 1–10 RPE (rate of perceived exertion):
RPE 5–6 — "comfortable hard." You could hold a short, broken conversation. Not a full sentence without pausing to breathe — but a few words. This is your target for the bulk of the bike.
RPE 7 — the danger zone. You feel strong. You feel like you could hold this all day. You cannot. This is the effort that wins you the first 40km and loses you the last 15 of the run.
RPE 8+ — reserve this for race day emergencies only. A headwind section you need to get through, a hill, the last 2km into T2. Not a pace to hold.
If you're not sure whether you're at 5–6 or 7, you're probably at 7. That's not a joke — it's the single most common mistake I see. In that case, ease off. You'll thank yourself at kilometre 15 of the run.
The First 20 Kilometres Rule
No matter how good you feel — and on race day, thanks to adrenaline and a taper, you will feel unreasonably good — hold back for the first 20km of the bike.
This is non-negotiable. I don't care if the course is flat, if the tailwind is pushing you along, if your legs feel like they belong to someone twenty years younger. The first 20km is not where the race gets decided. It's where the discipline to not decide it early gets tested.
I've raced Ironman 70.3 Westfriesland twice. Both times, the temptation in the opening kilometres was the same — flat roads, fresh legs, easy speed. Both times, the athletes who blew past me early were walking by kilometre 15 of the run. Start conservative. You can always add effort later. You can never get back what you spent too early.
Why Your Run Should Feel Too Slow at Kilometre 5
Heart rate drift is real, and it works against you specifically in the run off the bike. Your heart rate climbs for the same effort as the run goes on — dehydration, heat, and accumulated fatigue all push it up, even if your pace stays exactly the same.
That means if you start the run at your goal heart rate, you will be over it by kilometre 8. And once you're over it, you're not managing the race anymore — the race is managing you.
Start slower than you think you need to. "I felt so good at kilometre 5." That feeling is not information. It's adrenaline and a fresh pair of legs that haven't yet found out what the bike did to them. Ignore it for the first five kilometres. Let your heart rate — not your legs — tell you when to push.
Racing a 70.3 in Dutch Summer Heat
If your race falls in a Dutch summer — and most of the ones worth targeting do — heat changes the maths. You won't have trained in it, because the Netherlands doesn't really give you the chance to. That's not an excuse. It's a planning problem, and it needs a pacing adjustment.
Walk breaks at aid stations are not weakness — they're strategy. A 30-second walk to drink properly beats bonking at kilometre 18 every single time. Have a backup fuel plan before you need it, not after.
The three numbers to write on your wrist
Bike target: RPE 5–6 (or your equivalent watts/heart rate zone from your last field test)
Run pace for the first 5km: goal race pace + 10–15 sec/km
Heart rate ceiling for the run: your threshold heart rate minus 5–8 bpm
That's it. No spreadsheet, no complicated race plan you'll forget by kilometre 30. Three numbers, on your wrist, checked honestly and often.
Getting your zones right in the first place matters more than any of this — a plan built on guessed numbers is still a guess, just a more confident-looking one. That's part of what goes into every intake call I run, and it's the same principle behind why most amateur triathletes train too hard on easy days — the discipline to hold back when it's not time to push yet is the same muscle, whether it's a Tuesday session or the first 20km of a 70.3 bike leg.
Nutrition is its own piece of this puzzle, and it deserves its own attention.
If you're targeting a 70.3 in the next 12 months, this pacing framework — tested, adjusted per course, and built around your actual numbers — is exactly what Race Ready coaching is built around.
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