I was new to folding bikes. In February this year while I was in Taiwan, I visited several stores specialized in folding bike in Taipei area. First of all, I must say that I am not the one really "into" bicycle as a hobby, therefore, I will not spend extra money for some thing which is not better as a mechanical bicycle, just different. Here are my conclusions:
(1)In modern manufacturing, a bike company make only the main frame, the rest of the components are supplied by other manufacturers which can be located any where in the world. Some companies don't make any thing, they order every thing and assemble them together to be their own brand. The frame materials can be divided into two: carbon steel (plain carbon steel and alloy steel such as 4000 series), aluminum alloy (6061 and 7005). I exclude carbon fibre re-enforced plastics. Bikes with steel frame are usually heavy (13-15 Kg) but stronger. If you are a heavy person, say 200 lb, you are better off buying an iron folder. The problem of steel frame is, it will rust over time. The price of iron folders is in the range of 1,800 - 3,000 Taiwan dollars. I exclude iron folders by brand name such as Dahon, you'll pay extra for their established name, not necessarily will ride better. Folders with aluminum frame weigh around 10-11 Kg, price starting from NT$5,000.
(2) The front to rear axle distance is usually one meter. Some bikes have the seat tube and front tube angled to accommodate taller riders. You have to try the bike in question to see if it fits you.
(3) I was looking for a folding bike for use as a mixed transportation and for occasional touring in the far-away land. The only choice is 20” wheels. In this category, there are 2 rim sizes: 406 and 451mm, the corresponding tire diameters are roughly 19” and 21”, respectively. I have one of each in tire diameter. I also bought two spare 406 rims with 48 spokes for installing bigger tires.
(4) Steel or aluminum? I tried both and felt the difference in effort to propel a 15 Kg and 10 Kg bike is quite considerable, particularly when going up hill. My final decision was to buy a 10.5 Kg aluminum bike with 451 rims (BAHIS B3). In fact, the two steel bikes of GINORI and SRS brands I tried were very well built and had full suspensions for only NT$2,800. I might get one of those in the future for short commuting such as for going to the grocery store. BAHIS B3 and WEMAX X5i (451) were the two finalists for me. In the end, I chose B3 for its anodized coloring.
(5) I am very happy with my cheap folder, GOAL GT1, ($85). This is the bike I am going to keep and sell B3. Next time I go to Taiwan, I'll buy an aluminum folder with full suspension.