Road Cycling Industry Wikipedia Pages

This page lists notable United States bicycle brands and manufacturing companies.

Many bicycle brands do not manufacture their own product, but rather import and re-brand bikes manufactured by others. uring different times in recent history Giant has manufactured Terk bicycles with Trek logos, then Trek would pay Giant Manufacturing for the finished product. 

Many large brands that are manufacturers as well as re-branders: a company with manufacturing capability may market models made by other (overseas) factories, while simultaneously manufacturing bicycles in-house, for example, high-end models.

Wikipedian, not a bad place to start Road Bike Purchase Research.