The Ironman bike—180 km of rolling torture—decides podiums. Kristian Blummenfelt’s 4:02 split in 2021 Kona crushed records; amateurs average 6-7 hours. In 2025, Daniela Ryf hits 4:25 women’s bike. This 750-word guide covers aero position, pacing, fueling, drills, gear, and fixes to shave 15-30 min.
Aero Position Essentials
Drag = 80% resistance at 30 km/h. Drop 100W with tweaks.
- Base Bar Time: 70-80% ride. Elbows 90°, forearms parallel, head neutral.
- Pad Stack/Reach: Stack 55-65cm, reach 45-50cm (pro fit). Saddle 5-9° nose down.
- Helmet: Tail 1-2cm past spine. No vents forward.
- Kit: Skin suit, shoe covers, low socks.
Wind tunnel: 10° yaw saves 20W. Bottle behind saddle—5W gain.
Pacing Strategy
VI (Variability Index) <1.05. Steady power trumps surges.
- NP Goal: 70-78% FTP (pros 80-85%).
- Zones:
- 0-60 km: 72% FTP, build cadence.
- 60-120 km: 75%, negative split.
- 120-180 km: 70%, conserve run legs.
- HR Backup: 5-10 bpm below LT.
2025 IM Texas: Top-10 averaged 0.98 IF (Intensity Factor).
Cue: “Smooth is fast.” Ignore early rabbits.
Nutrition & Hydration
90g carbs/hour max. Gut train 12 weeks out.
- Plan: 2 bottles/hour (750ml)—1 carb-electrolyte, 1 water.
- Sources: Gels (25g every 20 min), bars (30g/hour), on-bike specials.
- Sodium: 700-1000mg/hour. Salt tabs if sweaty.
- Caffeine: 3mg/kg pre-bike, top-up 100mg/hour.
Practice: Long rides mimic—bento box, aero bottle refills.
Dehydration 2% = 5% power drop. Weigh pre/post: <1kg loss.
Key Drills
- Aero Holds: 4×10 min base bars, 90 rpm, 75% FTP.
- Sweet Spot Intervals: 3×20 min @88-93% FTP, aero.
- Negative Split Bricks: 90 km bike (easy-hard), 20 min run off.
- Hill Repeats: 6×5 min seated @95%, standing surges.
- Cadence Ladders: 5 min each 80-90-100-90-80 rpm.
Brick weekly: Bike-to-run transition—dismount practice.
Gear Checklist
- Bike: TT/tri frame, disc rear, deep front (50-80mm).
- Wheels: 60-80mm carbon, tubular tires 23-25mm, 90-100 psi.
- Crank: 165-170mm (shorter = aero).
- Drivetrain: 54/40 or 55/42 chainrings, 11-28 cassette.
- Power Meter: Dual-sided, calibrate pre-race.
Fit session: 3D motion capture. Saddle height = 0.883 x inseam.
Strength & Mobility
2x/week off-bike:
- Squats: 4×8 @75%
- Deadlifts: 3×6
- Core: Bike plank 3x60s (aero mimic)
- Hip Flexor Stretch: 2x30s/side
Plyos pre-season: Box jumps 3×10.
Race Day Tactics
Start: Draft legal? No—4-7m bike-to-bike. Draft illegal: 12m gap.
- Aid Stations: Grab bottles smooth, pre-open tabs.
- Hills: Seated climb <8%, stand >10% short bursts.
- Wind: Cross/head—lower front end; tail—raise torso slightly.
- T2 Prep: Last 10 km spin 100 rpm, shoes on pedals (flying mount).
Penalty box: 5 min for drafting—avoid.
Common Faults & Fixes
- High VI: Power spikes—cue “glass smooth.”
- Neck Pain: Helmet too far back—tilt 5°.
- Hot Foot: Loosen straps, carbon insoles.
- GI Distress: Train gut—start 60g/hour, ramp.
- Run Legs Dead: Over 80% FTP—dial back.
Bike computer: 3s power average. Review post-ride.
Pro Benchmarks
- Blummenfelt: 4:02 Kona, 310W NP, 91 rpm.
- Ryf: 4:25, 85% FTP sustained.
- Laidlow: 2025 sub-4 attempt—disc wheel, 88mm front.
Mental Game
Visualize segments. Mantra: “Aero, fuel, spin.” Aid station: “Grab, sip, stash.”
Final Kilometers
Bike leg sets run success. Lock aero, nail 90g carbs, hold 75%. T2 fresh—podium in sight.
(Word count: 758)