Join Date: Aug 2005
Location: San Francisco Bay Area
Bikes: 2005 Fuji Professional, 2002 Lemond Zurich, Folders - Strida, Merc, Dahon, Downtube, Recumbent folder
Welcome to the world of folders. I understand how daunting it can be to buy your first folder. There is so much variety in folders, much more so than with full size bikes, so it's really hard to choose, even when you know the brands and components.
Dahons and Downtubes are both reliable companies and make good bikes that will last. Dahon is obviously much more established and bigger. I have had many different models from both companies. I think you can be assure that you won't be throwing your money away when buying from either company.
If you're just looking for a functional, working bike, and you're not "brand-conscious", then Downtube bikes give you better value, in my opinion. Their frames are solid and reliable. Their standard shifters and derailleurs are not as good as Dahon's in general, but they work fine, and are easy to swap out when you are ready to upgrade. Downtubes are designed to use standard parts, and therefore are easy to fix and modify. There are many discussion threads in this forum, just use the search function and you'll be able to read what many of its users say about their bikes.
Dahon has many more models to choose from. You get a dealer network that can provide support. It generally costs a bit more, but their standard components are slightly higher quality.
So, have fun shopping, but you can shop with confidence.
PS: You're pretty tall, so make sure the model you pick can fit you well in terms of seat height and top tube length.