Folding Bikes - folder with least flex?

I've a Dahon Roo (well, it's rebadged into a SPecialized Globe), and the only thing I don;t really like is the noticable flex in the steering column. I know flex is a "feature" of folding bikes becasue of their frame design, but which is the stiffest out there?

Swift.

Bike Friday Pocket bikes, excepting the Tikit which is a bit flexy.

Yes, Swift is also good.

Swift

BF's are excellent bikes, but from what I can tell aren't quite as stiff. The handlepost and seatpost are both is a lot longer than the Swift, therefore more likely to have some flex. Also, the Swift's tubes are larger and made of aluminum, both of which add to stiffness.

That said, afaik both are significantly stiffer than the Dahon, and it's likely either one will work fine.

R20.

:)

Swift, BF and twenty are, as everyone else is saying, probably the stiffest. The only way you might do better would be with a full-sized bike-- Montague, Ritchey breakaway, Dahon Cadenza, or something coupled with S&S couplers.

You can pretty much generalize here, the shorter the steering lever, the less it will flex... materials being similar, a long telescoping post will flex substantially more than it's shorter counterparts.. the bikes without a folding steering lever will usually be stiffer again .. The Swift is comparatively stiff (but due to its rather long lever) will not be quite as stiff as the Pacific Reach, the TSR Moultons, Airnimals, and the like with less lever above the headtube bearing .. in a folding post, the Birdy (left short) is one of the best.. Dahon's one piece short handleposts (like on some Jetstreams) are also good....

[QUOTE=Gotte;9014242..........and the only thing I don;t really like is the noticable flex ............ I know flex is a "feature" of folding bikes becasue of their frame design, but which is the stiffest out there?[/QUOTE]

Does it actually matter?

An interestig article on wheel "flex":

http://www.sheldonbrown.com/rinard/wheel/index.htm



John

down tube NS is pretty solid IMO

Swift. Mine's stayed stiff over a year and probably 1500 miles.

Moulton/APB/TSR, Brompton, Strida.
Brompton is quite stiff in lower frame, and Strida has v stiff bars due to closed triangle frame compared to open 'F' Frame.

As John said, Wheel flex IS important, and some springy frames are much more efficient than 'solid' frames, all depends where the flex is :-) ... my 1p worth anyway.

Moulton/APB/TSR, Brompton, Strida.
Brompton is quite stiff in lower frame,.

IMO a Mezzo frame is a lot stiffer than a Brompton, Bromptoms standard bars flex like crazy(i know they are suppose to), I swopped them for straight ones.
The main area of flex on the Mezzo is the seat post

Any IF model (if you can find a dealer) the frames are pulled into tension on folding making them immensely strong! Hope this helps.

Unwobbly riding! Chop!

brompton S-type not the others.

The problem is that none of the stiff ones mentioned are actually folding stems (but detachable stems).
Stiffest built still is a single piece fork, plus ahead stem.

Out of the folding stems the one's from Dahon are comparatively stiff, due to their conic shape with larger diameter below.


...in a folding post, the Birdy (left short) is one of the best.. Dahon's one piece short handleposts (like on some Jetstreams) are also good....

I like the short one from the Jetstream XP with the Syntace VRO most. Fairly stiff. And gives a perfect geometry for me (186cm tall).

The Birdy hinges are not as nicely integrated as the Dahon "Fusion" ones, and also I would not recommend any telescoping and clamping in a handlepost.

Swift: very stiff (the designer really nailed it with this one, doesn't look stiff but it is superb)
Reach: frame very stiff but some minor flex in handlebar area
Moulton: stiff as (but not a folder)
R20: very stiff indeed, mine has some handlebar flex due to my own design of modernising it.
Downtube Mini: typical flex but maybe better than lightweight Dahons (haven't tried a MU though)
Birdy: Typical flex but quite a lot better than Dahons

Birdy: Typical flex but quite a lot better than Dahons
Dahon offers a bunch of different stems. All these stems are interchangeable, i.e., should work on any Dahon.
The Fusion2 (http://www.dahon.com/components/deluxe/fusion2.htm) now has a V-Clamp from outside. It comes in different length, telescoping and non-telescoping. The ones on the Jetsteams are shorter and non-telescoping. These are the stiffest.
I did not do an extensive comparison, but from some test rides with other folders, I think these Dahon stems are stiffer than all other folding stems, including Birdy.

If you have a telescoping post, I recommend an ahead conversion (chop of the QR and use a reducer), see this pic:

Does it actually matter?

An interestig article on wheel "flex":

http://www.sheldonbrown.com/rinard/wheel/index.htm



John

My only real concern, whether it's warrented or not, is that with an alu frame and components, the flex will lead to metal fatigue and failure.
As for the ride, I don;t mind it so much. In some respects I wonder whether it even helps a little with taking out some of the road buzz.
Obvioulsy too much flex could give you a sense of unresponsiveness and poor handling. Again, whether that's the case or not, I don;t know.

I really liked the Swift for its stiffness. Didn't fold as small as I wanted it to though.

Birdy with old style frame and non extending stem seems reasonably stiff to me.

David

Airnimal Joey's have to be the stiffest folding bikes I have ever tried personally, the aluminium makes it almos a little too stiff in terms of road vibration over long distances.The Bike Friday NWT is probably the second stiffest folding bike I have ridden and is steel.
The Tikit is slightly flexy, but still performs really well over long or short distances, and it is 100% CoMo steel.

My Montague is wicked stiff, guy. But seriously. No flex or slop whatsoever.

My Brompton S-Type is a lot stiffer than the Dahon MU SL that I used to own.:thumb:

Test rode a Giant Halfway last week and figure jumping curbs with this would not be an issue... it has a very solid feel and I would liken to to a Twenty in that respect.

IMO a Mezzo frame is a lot stiffer than a Brompton, Bromptoms standard bars flex like crazy(i know they are suppose to), I swopped them for straight ones.
The main area of flex on the Mezzo is the seat post

I've got a very flexy I-Beam seat post on my Vitesse and it's great for absorbing small bumps, much nicer than the standard stiff Dahon seat post.

Folding Twenty

My ('07) Dahon Cadenza is flex free. :thumb:

I think there a few different things being confused here.

There's frame flex, there's slop in the design, there's slop due to poor maintenance, there's negligent assembly, and there's negligent manufacture.

It can be difficult to separate them, especially since some are meant to be features (ie one bike's "suspension" system is another's slop).

That being said, stiffest folders I've ridden are the Mu (w/ SL stem) and the Airnimal Joey. Flexiest are the Tikit and maybe the Brompton (though it might be more accurately described as mushy). However, this isn't to say that all Mu's and Joey's are stiff or all Tikits and Brompton's are flexy. IME, you unfortunately just can't pick a model and assume all copies of it are the same because a folding frame is not a static piece of metal, but a moving part.