My Bafang BBS01b converted Dahon folder has a "Rebar", a strut supporting the hinge, which I have on good authority never end up back in the shop with a broken hinge. I don't know what the size of the bottom bracket is on this one for example, but I'm sure if you ask CW White, they'll be able to tell you - they used to do Bafang BBSXX conversions:
Dahon models that we build in our workshop from New Dahon Framesets and New Parts especially either to create a combination that Dahon do not currently produce, or just to give increased value over the normal model range.
foldingbike.biz
An example of a larger folder with rebar on Amazon (out of stock)
Shop 2014 Dahon Espresso D21 Folding MTB. Free delivery and returns on all eligible orders.
www.amazon.co.uk
Many of the newer Dahons, Terns and other folders don't feature the rebar. The owner of CW White knows far too much about folding bikes, and is a great source of spare parts and advice.
Some of their other custom builds:
Dahon models that we build in our workshop from New Dahon Framesets and New Parts especially either to create a combination that Dahon do not currently produce, or just to give increased value over the normal model range.
foldingbike.biz
I purchased my kit from IEBIKE on Amazon last year:
Shop Bafang BBS01B 36V 250W Mid Drive Electric Bike Motor Ebike Conversion Kit Mid Motor for Mountain Bike Road Bike. Free delivery and returns on all eligible orders.
www.amazon.co.uk
They have found some sort of UK based warehouse since my purchase, but diagnostics are still done in China - if anything goes wrong, you'll be posting faulty items back there. There are many UK sellers, who I'm sure others on this forum have experience of, and can recommend. If purchasing from IEBIKE, ask first via message about what stock they hold in the UK! Waiting for the slow boat from China would be very disappointing.
Here's a conversion video. It's pretty easy. His kit is illegal: