CrimsonEclipse

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Sammyboy

Downtubes other than the Nova are significantly stronger built than the others you mention.

davecriswell

Montague uses a folding system that doesn't use any cuts to the frame and doesn't require a hinge to connect two pieces of a cut frame. They fold around using a system in the seat tube - makes for a strong frame and stiff ride.

chagzuki

It strikes me that the frame hinge on my Vitesse is excellent, I've not had to adjust it once in 3 years, it's locks instantly and appears to distribute force well. Recently I've been looking at the designs on lower-end bikes and they work OK but are more irksome in terms of utility. Whether they fail or not would I imagine be down to the quality of the metal and welds. . . I don't know if those factors remain consistent within brands; I'm not sure any useful comparison could be made. If welds are visibly messy/uneven then that sounds alarm bells.

camroidv27

I would recommend staying away from the Citizen line when it comes to hinges. I had one break on me (at the weld), and they never felt too sturdy. I have to keep adjusting the locking screws on both hinges to keep the hinge tightly locked (once or twice a week). Soft metal screws are used and I worry they can strip out after all the tightening I have to do.

Dynocoaster 

Dahon has some pretty strong hinges.

vmaniqui

when you're talking about strong hinge, i would say it's about the same for downtubes and dahons but not on citizens.

Sammyboy

I think purely to look at the amount of materials used, the Downtube is stronger, but I would still totally trust a Dahon hinge for humans. The Downtube would be significantly better if the rider was a rhino or a rodo bull.

BikeKraft

There seems to be plenty of metal in the Citizen Bike hinge (Barcelona), but also plenty of slop.
I feel this slop allows movement between the two frame halves while closed and locked. This motion works against the locking part of this system. Again I say, I'm no engineer, so forgive me if this makes no sense. So tighten the lock gizmo, ride some, darn, it's loose again. Tighten, tighten, tighten, something has to give sooner or later.
Attached is a photo of the metal backed rubber washer that the quick release lever rests against. It's collapsing. I'll have to do something here. My wife loves the bike. Maybe have it welded solid at the hinge. Still thinking on this one.

Abneycat

In 20" bicycles, it is likely bike friday. Their folding design allows for bicycles that can hold an excess of a 220 / 260 lb. rider plus gear (up to 100 additional pounds of gear when I spoke with bike friday on the subject) and then be used for off road touring on top of that (bike friday pocket llama)

No other manufacturer makes a 20" folder that will come anywhere close to boasting that spec, to my knowledge. bike friday is also a very performance oriented company though, and their bikes are more costly than most dahon models, and far more expensive than any downtube.

The downside of that folding design is a larger, more awkward and slower fold - but try taking your dahon or downtube on a full fledged wilderness ride, or bunny hopping it constantly, or riding down stairs, etc..

I would only recommend trying all that on a llama, because even if the hinge on one of their other models didn't fail, the frame overall isn't made for that kind of use.

Montague folders are mountain rated, however, they are not standard folders, but full sized ones. They also cannot accept a full fledged cargo rack and still fold, which is a huge and killer downside to me, but people who are okay with seat post racks or carrying things on their back may not mind.

As for the more mundane folders like dahon and downtube, I think you'll get a lot of subjective and / or opinionated responses there as well. I think that would depend on the type of dahon being compared, as they come in a wide range of materials and hinge styles. I really have to doubt that the answer to your question here is simple. Neither brand has any constantly plaguing hinge trouble that I am aware of.

chagzuki

@BikeKraft: yeah, of course if there's any play in the mechanism then there'll be undue stress on particular parts. And the more precise the manufacturing the more evenly force will be distributed. Since I've had my Dahon I've seen a lot of forum posts about hinge problems, I guess I've been lucky in that it was properly adjusted in the first place and the threadlock has kept everything intact. Now I'm wondering if I ought to have taken it apart periodically to prevent seizing/bonding of parts. . . but I don't think there's anything that could seize.

Dynocoaster 

The different Dahon hinges
https://www.dahon.com/technology/v-clamp-technology
https://www.dahon.com/technology/lock...nge-technology
https://www.dahon.com/technology/lattice-forged-hinge
https://www.dahon.com/technology/doublelok-technology
https://www.dahon.com/technology/vise...ing-technology
https://www.dahon.com/technology/torsiongroove
https://www.dahon.com/technology/greaseflow-technology

camroidv27

Having just received a Dahon Boardwalk S1, and having the Citizen Miami, I can say for certain that the Dahon's hinges are MUCH sturdier and work better than the Citizen's. In fact, the whole bike feels much better and sturdier than the Citizen, and lighter too! I can't say anything about the Downtubes though, sadly.