Tynan said:
and they really tear along, no idea what the gearing is like but they're patently not slow in the hands of a decent rider
We used to ride full sized bikes, but neither of us could say our bikes fitted us properly, particularly my wife's. I bought her a fairly dear one, but never having found a really competent LBS, didn't think that even that one was the right size.
We like to take our own bikes on holiday with us, & the rack on the car was often a pain. A couple of years ago I discovered there were such things as folders, & after some research, bought one weighing 10Kg's, just 1 gear, very simple, British designed & a neat, fast fold.
About a month after buying that, my wife decided it was the best fitting bike she'd ever ridden (we're both about 5' 7") & found it easier all round since she didn't have to worry about complex gears, so I bought another. Since then we've ridden many miles on them. Although only 305mm wheels, we ride light off road as well as tarmac & find them about as comfy as my wife's 26" hybrid bike, but far, far more convenient, & a lot lighter & easier to manoeuvre.
Surprisingly we often pass riders on mountain bikes in spite of only 1 gear (56") so I suspect a lot of mountain bikes are bought where a simpler, lighter bike would do fine.
I've since bought another folder with 406mm wheels, which has an awful fold compared to my first one, is heavier, though still aluminium, but has a Suntour 9 gear derailleur, so for really long runs & up steep hills, is easier & faster than the simpler bike. It's also a bit more comfortable over longer rides, having front & rear suspension, although it's only cheap suspension & is bound to soak up some power input.
Because they fold up so small in comparison to a full size bike, should there be any mechanical problems that can't be fixed at the roadside, folders are much easier to transport via other transport, for example, a taxi, friend's car, bus or train.
I doubt we'll ever get another full size bike again. I'd really like a folding recumbent, as my recumbent (also small wheels) is my most comfy bike, but it's not easy to transport even in a car. There are a very few folding ones, but at eye watering prices!