I may be wrong about this because I'm very new to rode bikes, but I'm a computer tech who was trained to give initial ergonomic evaluations....

I would worry about Carpel Tunnel with straight bars but I'm not sure about with drop bars. With the straight bars you would want to be upright as possible because your wrists are not in a very ergonomic position. Your hands are holding your arms up and it would be easy to bend your wrist, impeding the nerve.

With drop bars, you rest your hands on the hoods or in the drop. Your hand is like you are shaking someone’s hand. When I'm in the drops, my hands are resting on outside of my hand (pinkie side). When they are on the hoods, it’s the same only my thumb seems to be more involved and will get tired. I will briefly put my hands on the flat upper part.

One thing I did find out with the drops....I have to have my handle bars level with my seat or I will put too much weight on my hands.

This is just my experience and observations. Hopefully others with more knowledge will weight.

- Mary