If you buy a new Bike Friday, they will build it to size, and help you with a custom gooseneck stem.

90 kilos is closer to 200 lbs, but most of the Bike Fridays should be able to handle that (as well as most other folding bikes).

You can either use a hard case or a soft case with the Bike Friday. The hard case can be converted into a small trailer, and if done right, will qualify for airline travel.

It is a bit of a pain to pack most folding bikes into an airline compliant suitcase, but with practice, you can get the bike torn down or reassembled in about 15 minutes or so. Of course, it is much quicker to fold to carry onto a bus or tram.

I have seen a bag that clips to the top tube, and then folds down over the folded bike for public transport if you wish, at least for the former Bike Friday Tikit.

There is a Bike Friday Crusoe that has been stuck on our local Craigslist for some time. I'm not quite sure why it hasn't sold yet.

https://eugene.craigslist.org/bik/d/...726627055.html

It is listed as a "large", but is probably more of a "medium" size as it appears to have a relatively short seatpost mast, and a tall, but not so long Gooseneck stem. I could help facilitate shipping it, but an international sale could be problematic as you couldn't try it first. Where are you?

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I haven't personally tried a Dahon Speed D7 that you are interested in. I do have a cheap Chinese alumium folding bike that just seems funky. Anyway, I'd say to test ride your bike if you can. See if the gearing is comfortable for riding on level ground as well as hills. My aluminum folder is just slightly short, and feels really awkward for riding up steep hills.