Originally Posted by banzai_f16
True. And of course we don't know just what kind of a "road" bike this "hybrid" is turning into. It will never be a racing bike, because there are some fundamental frame geometry issues that cannot be changed. Turning a hybrid into a "road friendly" bike can be as simple as a slight lowering of the handlebars, swapping the knobbies for semi-slicks or invert treads, and slapping a different handlebar on.
However, I still believe the neck pain is being caused by the fact that as the OPs handlebars get lower, he hasn't changed the width yet, or maybe bought a bar in an inappropriate width. The bars are too wide, and that's the root of the problem.
Oh, and to the OP, I don't even know if it's possible on a hybrid convert, but don't put those handlebars lower than the saddle. The geometry should not be right for that anyway.
Interesting, I'd never considered handlebar width. I'll have to look into that. What I've done so far is simply to put on thinner tires (700 x 25) with invert treads and lower the bars. My bars are now even with my seat. But I'll be sure not to put them too low, though, thanks for the tip.