Attempting to group folding bicycle {brands, manufacturers, models} is difficult as most manufacturers have their own base design and stick to it; differences among models or revisions tend to be small — to the point that some manufacturers are effectively "one product shops". Then the identity and product become even more interlinked (making it even harder to distinguish what is a model, what is a make, what is a brand, or what is a manufacturer). As such, some flexibility needs to be allowed.
Brands / Manufacturers / Models listed are limited to those notable enough to already have a Wikipedia article. For more information about navboxes, see WP:NAVBOX.