What is the 75% rule in cycling?

The 75% rule in cycling has two main meanings in Australia, one for training and one for racing and group riding. In training, the 75% rule is a popular guideline that says 75% of your riding should be at low to moderate intensity in Zone 2, and only 25% should be hard efforts in Zone 4-5. This polarized training approach is used by professional coaches to build aerobic endurance while avoiding burnout, and is backed by research showing that elite cyclists spend about 75-80% of their time at easy conversational pace. For example, if you ride 8 hours per week, about 6 hours should be easy endurance riding at 65-75% of max heart rate, and only 2 hours should be hard intervals. In racing and bunch riding, the 75% rule can refer to the UCI and AusCycling rule where if you are lapped or fall more than 75% behind the race leader, you may be pulled from the race for safety. In group riding etiquette in Australia, some clubs use a 75% rule meaning you should stay 75% focused on the riders around you and only 25% on your bike computer, emphasizing safety and awareness. There is also a 75% rule for bike fit, suggesting your handlebar height should be about 75% of saddle height for endurance comfort, though this is less common. The training intensity meaning is the most widely used when cyclists talk about the 75% rule.