The only way to get 28/44 is to use a 110 BCD crank, since you won't find a 130 BCD 28 chain ring. Another way to go is to keep the 130 BCD and change the sprockets on the hub to achieve the gearing you want. You could go with the chainring you have and put it on the outside, adding a 38 tooth on the inside. By consulting the Sheldon Brown gear inch calculator you can enter different combos. The Sheldon gear inch calculator is the only one I've found that provides the 349/ x1 3/8 wheel and tire combination used by Bromptons. Having said all that, mine has a 110 BCD with 38/58 and a 2 speed hub with 12/ 16 sprockets that gives me 78 /58 with the 58 and 51 /38 with the 38. If I were to use a 28/44 I would use the inner 2 options but probably need a longer bottom bracket to allow for a fold. I have considered having three chain rings but it doesn't look like it will fold properly. Unless you use a 3 speed hub, the problem for me is getting high enough gears with those little wheels.