Brompton wingnut-style latch
 

I'm watching youtube vids of the brompton fold and I don't understand why they use these types of latches. Most of the folding time is spent spinning the little things. Do all bromptons use this mechanism?

The Company is very keen on longevity & high reliability.

Have a look at their philosophy here:

http://stridasingapore.com/forum/ind...ic,2104.0.html

I agree. I don't think I spend much time spinning the wingnuts to lock/unlock the latches. When I stop, I know for sure that the bike is safe to either operate or stay in a locked folded postion. Plus when it is time to replace the latches and wingnuts, I will be able to do it myself with mininal knowledge or even no tools at all.

I agree, the wing-nut latches are slow and annoying. Pacific Cycles switched the Carryme's latch to a wing-nut from a regular quick release in 2008 (vs 2007).

I suppose safety must come first for a critical frame break like the Brompton has, but you really don't even need to close the latch at all on the Carryme (the rider's weight holds the frame against the headtube just like it holds the rear triangle in riding position on the Brompton).

Well, I'm not convinced. Other latch designs, as far as I know, are not prone to failure. I'd much rather have a q/r mechanism. I wonder if Mercs / Flamingos mimic the Brompton system.

I wonder, aren't these different QR pinch bolts compatible? So can't you just swap the wing-nut latch for a regular QR if that's your preference?

Older (non v-brake) Mercs have the same (admittedly with different handles on the nut - I don't know about newer ones but I suspect the same. I don't really see the problem; yes - a Dahon-style clip could work in this application but there's a hella lot more can go wrong with one of those and they don't even look that elegant.