Strange problem with Viking folding bike
 

Hi

A mate has this bike and I took a look at it yesterday because he couldn’t get the bars to stay in.

It has a quill steerer and the wedge can’t be tightened because it has a maybe 9mm nut at the top of the rod to do so - which is theoretically accessible in the tube at the point it folds open but there’s a screw that comes in horizontally, for the hand tightened clamp which holds the two halves together, blocking anything from getting to that nut. The furthest you can loosen that still leaves it very much in the way, it’s not possible to completely remove it to get a socket down there.

Anyone know how this is supposed to be done?

I should have taken a photo, sorry.

When you are talking about folding, I assume you mean the handlepost folding at its base, not the bike frame in half.

A quill stem with wedge usually installs and comes out the top; You loosen the long bolt just a couple turns then give it a downward tap to loosen the wedge, if needed another turn and tap, and remove the whole quill, wedge and all, where you can do adjustments if needed, before putting back together. Don't remove the bolt completely, as then tapping on the wedge will damage the last thread and you won't be able to get it back together, plus, the wedge will drop free if not on the bolt.

If the above doesn't apply, pics would help.

You may be dealing with rust. Spray a penetrating solvent in and let sit for a few hours. Turn the bike upside down and spray into the fork from the bottom after removing tire and fender. Let it sit a few hours. Loosen the bolt a turn or two. Try tapping it from above. This procedure may have to be repeated multiple time. The solvents need time to work. Good luck.

Got my friend to take a photo

hopefully you can see here how the nut I need to tighten (as suggested above) is visible in the steerer tube, but how the threaded rod for clamping the two halves of the handlebar post together obstructs access to it. This is as far out as that rod will go when you turn the handle, I assume it has some kind of limiter on it to prevent it falling out and being lost?

https://cimg1.ibsrv.net/gimg/bikefor...8e6c78e5a.jpeg

do you think that should just be able to be extracted further? I tried turning it with a decent amount of force and it seemed very “nope” but it closes up fine so it’s not stuck in position.

(above) I don't see the threaded rod you speak of, that clamps the hinge closed. However, my folder (Dahon Speed with old style handlepost) does have a threaded rod like that, when you open the hinge, it spans across the open area; There is sufficient space to get underneath to use a 10mm allen wrench on the headset preload bolt. But if I needed better access, like for a socket wrench on yours, I would simply unscrew the female threaded rod (it's right and left hand threaded like a turnbuckle), or remove one of the pins that connects it, I think one stays in place due to the threaded rod, and the other is held in place by circlips on each end.

EDIT: Now I see the threaded rod. Different setup. But yeah, figure out how to unscrew that to get access to where you need. Look for some sort of pin or snapon clip that limits its removal. You may need to screw it all the way in to see that.

Thread it back and then back it out a couple of turns . Use solvents. Using a block of hardwood or dowel and hammer strike the bolt hard .lf it is stlll stuck , apply more solvent and wait a day. Repeat .

My grasp of this is that the long quill bolt does not thread into the wedge, but instead has a nut underneath the wedge, that needs to be held to loosen or tighten, it's probably a nyloc stopnut. If true, it may not come apart out the top. Like I said, there should be a way to undo that cross-bolt further, to get access to the nut there.

Couldn’t find a nut at the bottom of the wedge. That was my first thought too. I’ll try threading the side clamp in to look for a collar of some sort, good suggestion.

I’m 99% sure it’s not stuck. This thing has been basically unused from new, sat in a dry shed for 3 years.

Other than modern Ahead type, I am only familiar with expanding wedge type.https://encrypted-tbn0.gstatic.com/s...gSgt2NMCUVC0EE

I'm guessing they have a wedge type, but perhaps the wedge itself is not threaded, but instead a nut beneath it. I've also seen a "cone" in place of a wedge, expanding the bottom of the quill tube which is slotted longitudinally.

Aheadsets are awesome, one of the great inventions.

Dahon handleposts like mine, the fork steer tube is threaded *internally*, and the handlepost base has a huge special bolt with 10mm allen, that engages there for preload, and then one bolt (steel base, I think perhaps two bolts on aluminum base) on the side that clamps the handlepost base around the smooth steer tube exterior. It's a good system that works as easily as an Aheadset.