Originally Posted by
wgscott
The main assumption is that more possible hand positions reduces fatigue. If you spend 90% of your time in one position on the drop bars, this becomes less compelling. You should ride whatever you find to be the most comfortable. There are many other options, like trekking (butterfly) bars, Jones bars, etc.
I think the discussion should have changed with the advent of these alternate (butterfly and Jones) bars. Perhaps it's just inertia; there's so much that's been written in the last 50 years, adding in new styles of bars to the "literature" will take a while.
But in the older sense, flat or mountain bars lock(ed) you into a single hand position. Compare that to four (at least) hand positions on drop bars. When your wrists and elbows get fatigued, it can lead to overuse injury if you've got to turn around and ride that far again to get home and can't change your hand position on the traditional flat bars. Drop bars? Move between the top, the ramp, the brifters or brake levers, and, of course, the drops.
And while it's technically possible to get your upper body low with flat bars, it's kind of like getting into a downhill racing tuck with your butt off the saddle and your nose on the stem -- not recommended for the faint of heart, strong in mind, or somebody without a lot of experience. But reach down and grab the drops, and you've just cut your wind drag enough to go a lot further before you're worn out. Safely.