spinconn

I am back to cycling after a long absence, but this time with an old but fit body. The age has brought me spine issues so I can no longer ride a true road bike.

I tried several types of bikes before buying a Giant Cypress DX. I like it but I want more speed and I only ride on pavement so I changed out the tires to skinny high pressure tires and got a big improvement. But I want more speed if possible, so I rented a road bike for a few days to see what would happen. I got more speed and I loved it, but my spine told me to stop riding that way.

I have been looking at what I can do while still riding in an upright position. I asked my local bike shop if I could just buy a road bike and install a high seat and flat bar and he said no, but didn't care to explain why, so I have been looking on the internet and now I am confused.

Though I used to ride a nice road bike I never did become educated on bike mechanics so I am not fluent in the technical aspects of bikes. However, it seems to me the issue for me comes down to geometry and the frame. So, for this question please disregard biker fitness and ability, pedals, gears, tires, etc. My question is strictly about frames.

1. Is there something about road bike frame geometry that precludes an upright position?

2. Aside from the aerodynamic advantages of a drop bar, does the drop bar position also provide a more efficient cycling position that cannot be duplicated or approached by upright cycling regardless of other aspects of bike configuration?

3. If, as I fear, the answer to the above two questions is in the affirmative, is there a light, stiff, responsive frame out there that would be best for speed and allow an upright position, even if not as fast as a true road bike?

I did not know what forum was appropriate for this so excuse me if this is not the correct one.