Robin Hood

Thank you for updating my knowledge of Taiwan, which was indeed learnt over a generation ago. In my defence, the bike is maybe nearly that old too! I have removed Taiwanese from the thread title* (it's still junk)
Edit: Looks like it only changes the title in the OP.

I tried to take a pic of the whole bike for you with my smartphone but the SD card is full and it appears to be incapable of saving it to the phone's HDD. So I used my dumbphone, and now I have problems saving it on my laptop! So, in the hope that this is better than nothing....

jur

That's not an early Dahon but it had a very similar steering setup. You will need to rotate that recessed nut with the 3 notches. Either a drift and hammer or a purpose made tool. There isn't much hope of finding such a tool in many bike shops, likely none. A pipe modded or something like that would be my way to go, assuming a pipe of the right diameter could be found. I once made a tool to unscrew a Sturmey Archer 8-sp hub by drilling and tapping a set of holes for some machine screws in a sturdy piece of aluminium, and having the screws engage the notches. Worked a treat.

Robin Hood

Hi again, I never did make that tool, so no photo! I decided to have one more go at tightening it, this time with a sledge hammer and an old chisel. Gave it a real final whack and the thing held out for 11 months (although only around a hundred miles). I didn't really fancy the idea of making the tool and then have to carry it around with me so I hit on the idea of tightening it again but this time hammering a thick sawn-off screw down into the side to wedge it in place. This seemed to work but came loose after just a few miles, so I presumed the forces had moved the screw out of position, On opening it up, I was perplexed to find the screw in place and that the lockring hadn't budged a mm! How is this mechanically possible?

BruceMetras

Take it apart and see if you have any bearings or races left to work with..

Robin Hood

Looks like I'll have to do that. So do I just turn the lockring anti-clockwise until it comes off? I really don't know how these things work, and I've even had to consult Sheldon Brown (RIP) to discover what 'races' are!

BruceMetras

If you were tightening it going clockwise, then going counter clockwise will loosen it .. don't take the nut all the way off at first.. see if the headset gets really loose with a few turns .. if it doesn't, then it's probably bound up and you'll want to whack it straight down with your favorite tool.. but you don't want to whack the shaft without the nut basically flush with the top of the threads, or you run the risk of damaging the threads (assuming you have any left) .. what you have there should be bog simple under normal circumstances, but it also might be damaged and need a little extra care.. if you do get it apart, take some pics so we can see what you are dealing with and then be able give reasonable advice..

cpg

Agree with BruceMetras advise and if you still get stuck I can give you the contact details for a chap in Mansfeild called Andy who fixes bikes. He is a retired engineer so might be able to do something with that locknut.

Robin Hood

What a great site this is; I get advice from the Pacific seaboard and somebody else can put me in touch with someone in my own smallish town!
Well, things do look bog simple under that ring. There's a split in the thread which I presume closes slightly as the lockring travels downwards, thereby clamping the (steering?) tube. Is this arrangement restricted to cheap-end bikes?
The lockring is at least 4mm thick but there appears to be a thinner ring underneath it, this time with no notches. Am I supposed to unscrew that too?

BruceMetras

Taking into account I've never seen anything like that in my travels, I'm thinking that the ring under the lockring should lift off and not unscrew.. probably some nice rust there.. penetrating oil might be your friend.. that ring would be the bearing surface for the lockring I'd guess ... more guessing, that whole mess should lift off of the shiny looking steerer shaft .. maybe some rotational force need be applied (after aforementioned lube is applied) .. so, is it really loose now that the lockring is off?

cpg

I expect the bearings to be under the large black bit that forms the stem hinge. Take care when removing it, lots of small ball bearings will fall out and roll away never to be seen again.

Robin Hood

Loose? the whole thing's a deathtrap now! Before buying penetrating oil, is it OK to try my WD40 first? (cpg please post the American equivalent if he's unfamiliar with Hertfordshire postcodes )

Before I risk that calamity, can you say how that might help me secure the lockring? When I tighten it fully the steerer doesn't wobble at all, so doesn't the solution lie above the ball bearing regions? I still can't work out how it managed to loosen when I thought I had it jammed by that screw. I did mark the bits but I'm now wondering if it rotated itself by exactly 360°, or more likely 720°. However, I'm pretty sure the screw would have been dislodged when the gaps passed it.

BruceMetras

Of course I meant looser than when the lockring was in place... don't try and ride the bike with the lockring off .. WD40 is fine to try.. vinegar attacks rust .. is it a wobbly mess now? as cpg mentioned, loose balls could be encountered .. don't work on the bike in the field or your garden.. put some cardboard down or something to catch fallen parts .. magnets are handy tools.. you're almost there...

BruceMetras

I see you're editing your post while I'm responding.. . at this point, you don't need help securing the lockring.. you need to find out what is changing when the lockring is initially tighten (and staked and marked in your case) and you go for a ride .. get the thing apart so we can see all the bits ..

Robin Hood

I clicked your profile and noted you were still on the thread, so I've stayed up a bit longer in anticipation of this second reply. OK I'll do what you say (unless cpg changes his mind ) but I can't help thinking that it's a design shortcoming where the Formosans have relied solely on the strength of a machine tightening.

curbtender

Looks like tightening that nut only holds the quick release on. Can you turn the ring under the cup? If so, you probably adjust that for your bearings and then hold it while you lock down that 3 notched nut.

cpg

Is WD40 named after post code it was invented in?

Sometimes loosening screw can be a mystery but what suspect is happening is that the bearing are worn or perhaps corroded. Some bearings will be more worn tahan other and so be a different sise and shape. As the assembly rotates, areas of slack occur arond the bearings that are the most worn and hence the tension on the lock nut reduses slightly. Over time the lock nut frees off. Thats my theory but it is only a theoory so to proove it you would need to disaasemble the steering, clean and check the bearings and if worn replace them, re-grease and reassemble. If you need to replace the bearings it can be cheaper to buy them at an engineering suppliers rather buying small bags sold in bike shops.
Curbtender's advise is worth a try before you disassemble the whole thing. Good luck

Robin Hood

The quick release mechanism closes tightly however loose the lockring is.


That prompted me to find out. After rather patronisingly questioning whether our Californian friend would know what it is, I discover that it was actually invented (and indeed named) in San Diego

Robin Hood

They're not; I lifted the whole handlebar assembly (including that hinge) clear of the bike, and there's another (secure) plate which no doubt covers the ball bearings. But these aren't the problem because removing those lower rings uncovered partially stripped threads, as Bruce was first to suggest. This of course explains why the lockring loosened despite being wedged so it couldn't rotate; vibration transmitted up the stem was popping it up over the damaged grooves. To me, the obvious solution would be to add ring(s) so that the cup tightens around the higher undamaged section, but I don't have any the right size. Can anybody think of something else that could perform this function?

cpg

plumbing washers, A-head spacers?

curbtender

You've gone that far, you need to check the bearings. Riding with a loose headset usually destroys them. At least you'll probably need to lube them.