Video:

- The shifters are mounted backwards from every other bike in the world, for petesake. And you can't just reverse them, as then they will be upside down.
- The gear range is too high, about 30-120 gear inches. I think a low of 20 is best, but for the same cassette range, that would put the high at 80, and a bit higher there is warranted. That is most easily accomplished by making the cogs bigger by 50%, and I'm sure with modern hyperglide, they could go a bit less than that on the high cog, giving a bit wider range for the cluster. The question then is whether the Brompton derailleur would work, or if it requires a road derailleur with more incline to the pantograph linkage, I'm sure any road derailleur would work, though might need a longer cage for the fold. By the way, the gearing I'm suggesting is what I have on my 20", 21-85 gear inches. But having a Brompton that would do the same would be nice. A standard Dahon has about a 32" low, that's not low enough in my opinion, unless you climb out of the saddle on all hills. Off the top of my head, instead of cassette 11-18 (11-13-15-18?), I'm thinking a cassette 14/15-18-22-27. EDIT: See below, a helpful suggestion from Splithub that I didn't think of due to slow and limited mind today.

I'm not a current fan of IGHs, but I've also said, in for a pence, in for a pound, so I think no disadvantage if they had just gone to a wide range IGH. Except... running the IGH in 2 (direct drive 1:00 ratio) while using the 4 derailleur gears, is more efficient, less friction losses.