The science of pacing in long climbs

Great climbing is not about one heroic surge. It is about distributing effort so your last five minutes are as fast as your first. The smartest pacing blends physics (gradient and speed), physiology (FTP, critical power, W′), and environment (heat). Here is how to turn those into a plan you can execute on any long climb.

Gradient-based pacing: when to push and when to hold

On a climb, most of your power fights gravity, not air resistance. As the gradient increases, aerodynamics matter less, so extra watts translate more directly into speed. That means it is typically faster to ride slightly harder on steeper ramps and slightly easier on shallow sections, while keeping overall metabolic cost in check.

• Shallow slopes (≤5%): air resistance still matters. Big power spikes give less speed per watt. Stay smooth and aero where possible.
• Moderate slopes (6–8%): gravity dominates. You can push closer to your target power without aero penalty.
• Steep ramps (≥9%): more of your power becomes vertical speed. Briefly lifting above target can be worthwhile if you have W′ to spend.

Keep cadence comfortable (typically 75–95 rpm). If you are forced below ~60 rpm, use easier gearing; grinding high torque accelerates local muscular fatigue and can burn W′ quickly.

Heat-aware pacing: protect core temperature to keep watts

Heat is the silent limiter. Around 75–80% of your metabolic energy becomes heat, and on long climbs convective cooling is limited by low airspeed. Rising core temperature drives heart rate drift, elevates RPE, and shrinks your sustainable power.

• Use an HR cap: if heart rate drifts >5–7% above your early-climb value at the same power, back off 5–10 W for several minutes to stabilize.
• Plan a lower base target in heat. Humidity and sun exposure matter as much as air temperature.
• Cool before and during: start hydrated, pre-cool (cold bottles, ice in jersey), pour water over head and arms when safe.

Use these as starting points and individualize with training data:

Base target (cool, 40–60 min): 92–96% of FTP or near CP for duration
Heat adjustment: reduce 1–3% per 5°C above ~20°C (toward 3% if humid/sunny)
Durability adjustment: reduce 1–3% per ~1000 kJ done before the climb

Fuel and fluids support heat tolerance and pacing:

• Carbs: 60–90 g/hour on the approach and climb. Start early; do not wait for the final third.
• Fluids: 500–900 ml/hour depending on conditions and sweat rate.
• Sodium: 500–1000 mg/liter as a starting range to aid retention.

Fatigue models for long climbs: FTP, CP, and W′ in practice

Two simple models help guide your effort:

• FTP/CP and your power–duration curve: set your base target from what you can truly hold for the expected time, not from ego. For a 40–60 minute climb, most riders land near 92–96% of FTP in cool conditions if fresh.
• W′ (anaerobic work capacity): the finite work you can do above CP. Surges eat W′; when it is gone, you will fade. On a long climb, save most of your W′ for steep ramps, drafting gaps, or the final minutes.

Practical rules:

• Keep W′ balance >40–50% until the last 5–10 minutes. If your head unit shows W′bal, use it; if not, use restraint: avoid repeated 30–60 s spikes >120% of FTP early.
• Watch decoupling: if lap NP stays constant but heart rate rises >5–7%, heat or fueling is the likely limiter—back off slightly and fuel.
• Account for durability: most riders see a small drop in threshold after large work. If you hit the climb with 1500–2000 kJ already done, expect a 2–5% reduction in sustainable power unless you are very well fueled and heat-adapted.

Fast climbers ride “even” internally and “smart” externally: steady metabolic strain, small power lifts only where physics and tactics pay you back.

Build your pacing plan

1. Profile the climb. Note length, expected time, average gradient, and where it changes (ramps, hairpins, flatter shelves).
2. Set a base power. From your recent 40–60 minute bests or CP model, pick a target at 92–96% of FTP if cool and fresh.
3. Adjust for heat and prior work. Apply heat and durability reductions from the guide above.
4. Define gradient multipliers. Plan to ride roughly 0.90–0.95x base on ≤5%, 0.98–1.03x on 6–8%, and 1.02–1.06x on 9–12%, keeping surges brief and below your W′ budget.
5. Budget W′. Decide where you will spend it (e.g., two 30–45 s lifts on steep ramps, a final 3–5 minute push). Keep W′bal >40–50% until the last segment.
6. Choose data fields. 3 s power, lap average power or lap NP, heart rate, W′bal (if available), elapsed time, distance to summit. If you use core or skin temperature sensors, monitor trends, not instant values.
7. Fuel and hydrate. Arrive topped up, then target 60–90 g carbs/hour and 500–900 ml fluids/hour with adequate sodium. Small sips regularly beat big gulps late.
8. Execute and review. After the climb, compare planned vs actual power by gradient, HR drift, and W′ use. Adjust your multipliers and heat reductions for next time.

Example: a 50-minute climb at 27°C, light wind

You: 70 kg, FTP 315 W, CP 305 W, W′ 18 kJ. You have ridden 800 kJ before the climb.

• Base target (cool): ~92–95% of FTP for 50 min → 290–300 W. Choose 295 W.
• Heat adjustment: 27°C, moderate humidity → reduce ~2–3% → 286–289 W.
• Durability: 800 kJ prior → reduce ~1–2% → 280–285 W base.

Gradient plan:

• ≤5% shelves: 255–270 W (0.90–0.95x of base) to limit aero waste and shed heat.
• 6–8%: 275–290 W (0.98–1.03x).
• 9–11% ramps: 290–300 W (1.02–1.06x), with brief moves up to ~325–340 W if needed. Keep any >CP efforts to <30–45 s and track W′bal to stay >50% until the final 10 minutes.

Monitoring:

• Power steady within ±10 W, using 3 s smoothing.
• Heart rate: if it rises >7% at the same power by minute 25, pull 5–10 W for a few minutes, pour water to cool, and resume.
• Final 6–8 minutes: allow a controlled rise toward 290–300 W as long as HR and RPE are stable. Spend remaining W′ on the last steep section.

Fuel: 30–40 g of carbohydrate in the 15 minutes before the climb starts, then 20–30 g every 15–20 minutes during. Aim for ~600–700 ml fluid with 600–900 mg sodium per liter across the hour in these conditions.

Key takeaways

• Use physics: nudge power up on steeper pitches and down on shallow ones—smoothly.
• Respect heat: set a heat-aware base, watch HR drift, and cool proactively.
• Manage fatigue: set targets from your power–duration curve, protect W′ early, and plan where to spend it.
• Plan, execute, review: refine your gradient multipliers and heat adjustments with each climb.

Mastering long-climb pacing is a skill. With a clear plan and a few rides of honest review, you will trade late-race fade for strong finishes—and faster times to the summit.