Thanks for the clarification, Amuro. That is interesting, AFAIK the 5.2 and SD are not even available in Europe. In fact, I had been led to believe that the LT was the successor of the 5.x series.
I have a happy ending to report. Strida Europe / Vanmoof have sent me a replacement – the SX – and it is functioning well. It has the new EN-style frame, which I am pleased to say does give me an additional sense of confidence, and feels nice and firm. Thank you to Vanmoof for the prompt and fair customer service; special thanks to Joffrey!
As for the SX itself: I am very pleased with the handling of the bike so far. I didn’t really think before that 18" wheels would make much of a difference, but it does seem zippier than the LT. My other concern was that the wheels would be too big for my commute, during which I stow the Strida on the luggage rack of a train, but this was not a problem. My recommendation would be go for the 18" wheels unless you have a specific need for smaller wheels!
Coincidentally, my first proper ride with the SX was on the day when we had our first snowfall here. It was mushy, icy stuff, which has often given me problems in the past. I had been planning on riding my Brompton instead, but it had a flat. 
So I gave the SX a chance, and I found that it felt much more stable in the snow, even with thinner tires! (It came equipped with 18" Innova 85 PSI tires.) Also, I didn’t get any ice accumulating on the belt or the rear freewheel, or getting stuck between the freewheel and the snubber. I think the snubber position was already improved on the LT. I wonder if this was just a happy coincidence, or whether Ming was gathering data from riders in snowy climates. 
I’m glad to read about these good news!
My words - Joffrey is a really nice guy!
A wave for Joffrey…
It’s really a happy ending. 
Congratulations! 
Interesting thread. It turns out that my Strida just had the same failure.
I did notice more creaking over the past year but never a crack forming. Anyway, I just contacted the USA Strida distributor and should get more information soon.
I’m very curious for their reaction.
Could you please tell us anything regarding age and approximately mileage?
You noticed creaking for “some time”, does that mean months or rather years?
Hello Guys,
I dont know how to start a new tread. Tonight while I was riding, my Strida broke out of the blue.
Fortunatedly, I was riding very slow and all of a sudden I fell sat on the road hitting my back,
and the back of my head on the road. When I woke up, I was there, lying on the road with a terrible headache and people surrounding me. I am still dizzy and my head is exploding, also am I very upset; the Strida was supposed to be a safy bike.
I call the Strida reseller here in Peru, and he mentioned that his own brother had the same problem, and that possibly it was metal fatigue. Of course, it was not. I had purchased that bike less than two years ago brand new, I had ridden it less than 8 miles per day mostly on safe bike roads.
What happened is that the tube (the one that holds the seat( broke in two pieces, as if it were perfectly cut with a knife, not with saw. I would like to post pictures, but I dont now how to.[photos.google.com/search/tra/photo/AF1QipPIJoX2V1eM2hX5fwoUoVDm8zHXdp5pdA-csVeo]
[img][photos.google.com/search/tra/photo/AF1QipMMpFf9WBww2ZPOBB3ks7ycuPE2pLvWRh-D-oLf]