If you pay attention to professional track racers then you’ve noticed this shift in cockpit width. For years, track racers have gone with a wide and flat bar. Also used in madisons, these bars still clear the forearms during sprinting and allow the racers to use leverage at its optimum positioning. Now recently the shift has gone back to a 39cm bar. Why? My guess is that it’s more aero and actually allows the racer to concentrate his power. But that just doesn’t make sense.
We all know that sprinting is a fast-twitch muscle action. Similar to dead lifts and hang cleans in weight lifting: exploding at the maximum capacity for a short amount of time. Track racers are now some of the worlds top athletes. When you dead lift and clean, you’re told to keep your grip as wide as your shoulders. So why not use this same ideology for sprinting? Sprinting is a high output along a narrow axis. Similar to why track Q-Factor is so slim, the bars of your bike, when closer together allow you to snap at a higher concentration with little or no energy loss. Your body is in a line, pushing forwards.
Looks like Cinelli had it right the whole time: 39cm is the way to go.