The most common pacing mistake in amateur cycling: going too hard in the first 30 minutes. A 5% overshoot early costs disproportionate energy later due to the non-linear relationship between power and fatigue. For sportives and time trials, target an even power output (by IF or NP) from start to finish. For hilly events, allow 5-10% above target on climbs and recover on descents. Power meters make pacing objective; RPE alone usually leads to starting too fast.