Pacing the bike on a hilly course (variability and the IF cap)

The principle

On a flat bike leg, hold target watts. On a hilly leg, holding target average watts means going harder than target on climbs and easier than target on descents. The Bike Power Plan calculator already accounts for this in its projected time (it models the course profile). The execution discipline is keeping your variability under control so the average watts equal the projected average without spikes that wreck the run.

The numbers

Two values matter on race day:

• Target average watts: from the saved race plan. Same for flat or hilly courses (the calculator already accounted for terrain in the projection).
• Variability index (VI) target: AdjP divided by average power. Lower is smoother:
• Flat 70.3 / 140.6: aim VI 1.00 to 1.04.
• Rolling 70.3 / 140.6: aim VI 1.04 to 1.08.
• Hilly 70.3: aim VI up to 1.10.
• Hilly 140.6: aim VI under 1.08.

A VI above 1.10 on long course means too many spikes. The run penalty for high VI is large.

On climbs

• Hold no more than 110 to 115 percent of target average watts on most climbs.
• For short steep ramps (under 1 minute), 120 percent is OK if it lets you keep cadence.
• For long climbs over 3 minutes, drop to target average watts as the climb continues. Spiking to threshold and cracking the back of the climb is the classic mistake.
• Pedal at the highest cadence you can comfortably hold. Spinning up climbs at 75 to 85 rpm protects the legs for the run.

On descents

• Pedal whenever it produces watts above 80 to 100 W. Free speed costs nothing.
• Do not push hard on descents to "make up time"; the watts vs speed curve is brutally non-linear above 50 km/h. Past about 55 to 60 km/h, more watts mostly produces more drag, not more speed.
• Aerodynamic position matters more than watts. Stay aero unless cornering.

On flats

• Hold target average watts plus or minus 5 percent.
• The flats are where average power gets dialled in. Use them to come back to target after a climb spike.

Power cap rules of thumb

If your saved race plan target is 220 W average:

• Cap on a 30-second climb: 270 W.
• Cap on a 3-minute climb: 250 W.
• Cap on a 10-minute climb: 235 W (target plus 7 percent).

Holding above 110 percent of target for more than 5 to 8 total minutes across the bike leg is a strong predictor of a bad run.

What to put on your bike computer

• 3-second power as the live read.
• Lap AdjP (or 30-second AdjP if your device supports it) for variability tracking.
• Average power for the leg so far to know if you are on target.

See also: Bike Power Plan calculator, Race plan reading, Yousuli bike zones.