Originally Posted by
BobbyG
The bottom bracket adapter isn't going to work... the seat tube intrudes just a hair too much for the narrowest sealed cartridge I found. I put the original crank back on and did some digging on the web And found a disk that replaces the single speed changing up front and has mounting holes for a 130 BCD ring which I already bought, a 60 tooth chain ring for upfront so this will take care of that period it's $27. I wish I would have known about this sooner but I Hadn't seen this solution on any folding bike discussion. However it's a common upgrade for bmx bikes apparently. Here's what I ordered stay tuned for more....
Another possibility: So I take it, the bottom bracket adaptor (I am unfamiliar with it), would have been an adaptor sleeve inside the BB shell? An alternate solution may be any of the new style cranks that use "external" BB bearings, with a tube BB axle that goes through the shell, that may be small enough to not have interference with the seat tube. My favorite is "hollowtech II" style, now widely available as generic, with "ISO External" bearings on each side. I use a 110mm BCD 50/34 double on my 20" wheel folder, but the same style is available in 130mm BCD as doubles and singles (notably, Litepro), and really low cost. That style has other benefits as well, but your key issue is fit.
Let us know how things turn out.