Dan Bigham Method for Triathlon

I have been a big fan of Dan Bigiham for awhile now and in fact I model a lot of Dan’s principles with my own coaching.  When we are told to “reverse engineer” your gaols, what does this really mean? 

Following on from my last post on “Money Ball for triathlon”, I again will use myself as an example for this so let’s take a look at using Dan Bigham “start at the end” approach for Ironman triathlons. 

This is a high-performance experiment, so the detail will reflect that.

Target: Ironman Cairns 2026 – Sub 9:45 or 9:30 as a stretch goal

Conditions: ~ 25-28°C, humid, strong winds, rough swim, rolling bike and hot flat run

Step 1: Define the end point – What performance do you need?

Goal: 9:30 – 9:45 total time

Swim: (3.8km) 1:05 (stretch 1:00) within AG pack, low cost

Bike: (180km) 4:55 – 5:05 NP of 220watts, focus on aerodynamics and decoupling

Run: (42.2km) 3:20 – 3:30 HR controlled, low fade

T1 + T2: 5-10min fast but calm

**** This sets the benchmark for all the backward planning  ****

Step 2: What does that require physiologically?

Swim:

• Threshold pace: ~1:33/100m for a 1:00 swim
• Cadence goal: 36+ SPM, even stroke count
• High focus on form and drag minimization

Bike:

• Race: NP: 220w required LT2 ~310-320 watts for a 70% IF
• Bike Vi: <1:03, stay aero and even
• CdA goal ~0.220 or lower
• Caloric demand: ~3300–3600 kcal → high carb intake (120g/hr)

Run

• Race pace: ~4:50/km (3:24 marathon)
• HR: 145–150 bpm
• Substrate use: Must be able to burn fat efficiently at this pace
• Tolerate 90–100g/hr carbs

Step 3: Environmental Reality – Heat in Cairns

• Must mitigate core temp rise
• Clothing, pacing, and fuelling must all support thermoregulation
• Execute heat adaptation phase: 8–10 sessions 8 weeks out, then maintain
• Use CORE temp sensor in training if possible

Step 4: Reverse Engineer Each Segment

Swim Plan: Efficient, Calm, Controlled

Goal: 1:00–1:05 with low stress and great pacing

Form-focused sessions	2x/week technique blocks: high elbow catch, streamline drills
Cadence training	Tempo trainer sets to push from 70 SPM over 12 weeks
Pacing control	Every session includes some 10–15min race-pace steady-state swims
Race strategy	Start just behind front AG pack, draft smart, minimize contact
Equipment	Speed wetsuit + tinted goggles for Cairns sun, well-fitted goggles to avoid fog

Bike Plan: Aero is King, Power is Secondary

Goal: 220W average, 0.220–0.225 CDA, <5% decoupling

 Equipment and Aero

Helmet	Aero helmet tested for yaw and head position stability
Suit	Light-colored, aero fabric suit tested in heat and wind tunnel (if possible)
Bike fit	Maximize comfort in aero for 5 hours: test pad stack, reach, tilt, saddle
Wheels	Rear disc (real or cover), 60–80mm front. Tire-rim match critical
Tires	GP5000 TT or S TR, latex tubes if legal, waxed chain
Hydration	Integrated aero bottle (between arms), rear storage for backup bottles

Aero Testing Ideas

• Field test 3 positions with same power (160–200W) on closed loop
• Use Aerolab in GoldenCheetah or Chung Methodwith CDA estimator
• Target: CDA drop to ~0.220

---

Training

Phase	Focus
Now–20 weeks out	High Z2 volume (FatMax 135 bpm), tempo strength (SE 60–80 rpm intervals)
20–8 weeks out	Race-specific: 3–5h race-pace rides, 70% IF, aero lock-in
Last 8 weeks	Brick focus, long rides in race kit in heat, steady pacing + nutrition execution

Run Plan: Durable, Controlled, Decoupled

Goal: 3:20–3:30 marathon, <5% pace fade, HR ceiling 150 bpm

Run power + HR	Use Stryd to normalize pacing in wind/heat/slopes
Bricks	Run 10–15 km off 4–5 hr rides 2x/month from week 12 out
Durability	Long runs: 30–32 km w/ last 10k at race pace, ideally fatigued legs
Cooling	Practice ice down front/back, sponges, aid station strategies in bricks
Fueling	Must hold 90–100g carbs/hr in late race without GI distress

Nutrition Strategy

Pre-race	Carb load 10–12g/kg over 36–48 hrs; 1000 kcal pre-race breakfast
Bike	110–120g/hr carbs (Maurten + sports drink + SaltStick), fluid every 10–15 min
Run	90–100g/hr via gels, mix with sports drink and water. Practice in hot bricks
Backup	Carry CrampFix and salt caps; test gut tolerance in race bricks

Heat Strategy (Critical for Cairns)

8-week heat prep	2–3x/week sauna, hot bath, or indoor Z2 ride at 30°C
Last 2 weeks	Reduce volume, maintain heat exposure until 4–5 days out
Race day	Light kit, full sunscreen, ice sponges, aid station targeting
CORE temp sensor	Used to model training sessions + core temp rise vs power decay

Training Load Strategy (CTL & TSS)

Phase	Weekly TSS	CTL Target
Base	900–1100	Build from 130–150
Build (20–10 weeks out)	1100–1300	Hit 160–170
Peak (8–3 weeks out)	1300–1500	Peak at CTL 180+ (Swim 40 / Bike 80 / Run 50 / Strength 10)
Taper	600–800	CTL dips to 165–170 race week

Mindset & Planning

Dan Bigham would:

• Test every assumption: aero, position, fueling, pacing
• Measure everything: power, HR, pace, temp, sweat rate, RPE
• Practice race day: gear, clothing, transitions, fueling, cooling
• Monitor fatigue & durability: decoupling, long-run pace, cardiac drift

Final Prediction Model

Let’s assume:

• CDA: 0.220
• Bike power: 220W
• Run pace: 4:55/km
• Decoupling: <5%
• Heat adaptation: complete
• Nutrition: fully practiced and absorbed

Result:

• Swim: 1:02–1:05
• Bike: 4:55–5:00
• Run: 3:25–3:35
• T1+T2: 6–8 minutes

Ironman Cairns Finish: 9:30–9:45