Unless you’re planning to change your bike fit for a particular reason, maintaining a position that your body has already adapted to maximizes both your efficiency on the bike and your performance on it. Most importantly, setting up your bike with consistent measurements will also minimize the potential for injury. Everyone’s specific numbers will differ, and a good bike shop will help you figure out yours, but these are the measurements that pros, mechanics, and you should be familiar with…
Level the saddle. Generally a level saddle is the most comfortable and efficient setup.
Measure from the top of the saddle to the center of the bottombracket spindle along the seat tube. Proper saddle height is key for power production and injury prevention.
From the nose of the saddle, drop a plumb line and measure how far the line is behind the bottom bracket. The saddle setback affects your balance point on the bike and its handling.
Measure from the center of the front wheel’s axle to the center of the handlebar. Flexibility and comfort are the biggest factors in handlebar height. Casual riders might have their handlebars even with the saddle, while competitive riders will be anywhere from 2-4 inches below it.
Measure from the nose of the saddle to the center of the handlebar. Like the handlebar height, your reach is also affected by flexibility and comfort. The more stretched out you are, the better your aerodynamics. The trade-off, however, is that you also close your hip angle, which inhibits power production.
6. HANDLEBAR WIDTH:
Measure the handlebars from center to center. You want your handlebars to be as wide as your shoulders. Any narrower, you compress your chest cavity; any wider, your aerodynamics suffer.