Yesterday we looked at how the body will find its ideal angles almost “despite” your efforts to put it in a different position. Therefore moving the handlebars lower will result in a more vertical arm position (as the shoulders remain in the same place). More vertical arms have two disadvantages:
- Aerodynamics. More vertical arms means more frontal area and a worse shape for the arm cross sections (same width, less depth in the direction of the airflow).
- Handling. With the arms more vertical and the elbow more stretched, handling is less precise. The more your elbows are in an angle, the more you push and pull on the bars which is good. Stretching your elbows means you’re “flailing” your arms more which gives less precision, rather than pushing on one side and pulling on the other. In descents, etc, this doesn’t really come into play as people will lower their back for the corners and pedaling action is not at peak performance then anyway, so this issue plays mostly when riding on the rivet in groups, especially in high effort, high stress situations like the classics on narrow roads. See also the advice from Henk Lubberding.
Of course, riders intuitively know all of this, or at least their bodies do. Which is why in the past 30 years as the trend progressed to move handlebars down, the amount of time spent in the drops has decreased and most time is now spent on the hoods. Which in turn explains why the riders of today sit just as low as those 30 years ago, despite having dropped their bars by 4″/10cm.