I am thinking to get a folder for this track (south down way in south England)
https://www.youtube.com/watch?t=235&v=bJy5xHQELg4

Never done any proper mountain biking before although I did own a cheap mountain bike but only used it in the city many years ago. A proper MTB will be ideal for this track of course but since I live in a small flat on second floor in London (the reason I got my current folder for commuting) so wondering if any folder out there can do this track.

Espresso got better gear range and bigger wheels, Jetstream got full suspension (not sure how good are these?). The front suspension on Espresso looks beefier but how good are they? Another option maybe Montague bikes but I don't quite like the folding methods of removing a wheel. My travel method involves many train travels so like the quick folding of Dahon.

Also best if the suspensions are standard parts so that I can upgrade later. The one on Espresso looks like standard parts (not sure). How about the front suspension on Jetstream, looks like a customized part?

DEBCAR Story

Thanks. I remember reading that (some link from this forum). It's amazing. But the front suspension is a very expansive German A kilo, not the one used on normal Jetstream.

I had a jetstream p8 several years ago and the front suspension had almost no travel and wasn't adjustable, i.e. was functionally almost useless.

I have got a birdie with big Apple tyres and a thudbuster seatpost. That copes very well if you want a compact bike. I recommend you ditch the chain catcher and run a small cage rear mech however.

I have owned the Dahon Jack (same as Espresso) and while it was a nice bike its still a big lump when folded. I now own a Montague Bi-frame which is much more compact. The newer Montagues should also be much more compact when folded, especially when both wheels are removed, which doesn't take long to do. Slip the whole thing in a bag and you should be fine on train.
You can take non folding bikes on trains, possibly consider a non folding bike - remove the wheels and rotate the handlebars when storing it in your flat if you can find a corner for it to live in.