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Old 05-18-12, 08:48 PM
  #14  
rodar y rodar
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Originally Posted by 5M177Y
Thanks for the replies. The handlebars (with a little force) rock back and forward. The nut that I am now assuming would tighten this appears to be stuck, and slightly rounded. There is another nut at the bottom of the stem, which I would expect to release the whole stem, I haven't tried loosening that one yet. So the thinking is that the plastic knob is for height adjustment? And could be stuck, but maybe freed by hitting it?
It`s tough to say exactly what you have there, or how its designed, but I`m going to take a guess that:
...the plastic knob is supposed to turn a long bolt or threaded rod which tightens the wedge at the bottom of your stem, the nut just above the handlebar clamp threads up and down that same long bolt to tighten the clamp, and the "nut at the bottom of the stem" is just the locknut for your headset bearings. The plastic knob is probably either pressed onto the end of that long bolt or has a threaded insert inside it and yet another lock nut to make it turn the bolt rather than just unscrewing itself. Just my guesses, and I could certainly be wrong.

Assuming that you need to adjust or remove the handlebars to fold or for some other reason, or that the swaying bars make it unsafe or a PITA to ride, I`d say you have little choice but to escalate the battle. If you can live with it as is, you might still be curious enough to operate, but you take the chance of mangling things more.

If you decide to go for it, some penetrating oil (WD40 works well) on the stuck nuts will help to free things up after several hours of soaking, though you still might be in for a fight. Then I`d try ViseGrips or ChannelLock type pliers to get the stuck nuts to move. If you manaage to get it all apart, you`ll be able replace the mangled nuts, but the long bolt might be tricky. If you`re able to get the clamp nut up a little bit so there`s some space between the nut and the clamp, try again to loosen the plastic knob, then smack it down like Jur said. That should hopefully free the wedge so that you can twist and pull the stem out. From there it will be obvious how it all works.

5M177Y, I have no idea how much experience you have at working on bicycles, or on bikes from what era, so forgive me if you already know a lot of this. Do you know how a quill stem works? You can google up a diagram if not- it`s very simple when you see one, but if you have no idea, none of our comments will make much sense. And the nut at the bottom of the stem- is it a large diameter, but very thin nut that the stem goes all the way through? If that`s the case, it almost certainly WOULD be the locknut for your headset bearings. Loosening that without being able to get the stem out won`t help you any- it just gives the little BBs in the bearings a chance to fall out and get lost. If you find diagrams of a threaded headset and a quill stem, you`ll be in a good position to try it yourself. If you can`t find those, or you just don`t feel like messing with it yourself, you could always take it to a shop and have the mechanics there give it a shot.

Last edited by rodar y rodar; 05-18-12 at 08:51 PM.
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