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Miyata ninetwelve problem.

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Miyata ninetwelve problem.

Old 09-23-08, 02:41 PM
  #1  
badmother
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Miyata ninetwelve problem.

I am cleaning up a great looking (dupster find) Miyata ninetwelve. The thing is in great shape, apart from a lot of oil, I supect engine oil cowering the whole thing.

Seatpost was no problem, just opened the bolt a little and it slided to the bottom position on its own.

BUT the stem did not.

I`we done both seatposts and stems on other bikes, but cheaper ones, this one I am afraid to destroy.

I put it upside down and put "rust killer" down the steerer tube three days in a row. Tryed to hit it from the top, but I am afraid of destroying the bolt. Also afraid of bending the fork legs.

I`we been thinking maybe I could find a slim candle, light it and stick it up the tube but I guess it is going to die out from lack of oxygen. Maybe a slim gasburner?

This is a great bike, so I want to try to ride it before I decide if I am going to keep it or sell it. It is too big for me (60), I am 5,8"- I am thinking of putting swept back (north road type) bars on it to be able to ride it without being too stretched out.

I am not happy to just leave the stem like this, I want to be able to adjust it, and I guess it is only getting worse if I leave it for now.

What would you do?

Last edited by badmother; 09-23-08 at 02:43 PM. Reason: 2PelliNg
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Old 09-23-08, 02:53 PM
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If your're worried about the bolt, hit it with a rawhide or plastic hammer or put a piece of soft wood like pine over the bolt before hammering on it.
For the fork legs, take the wheel out and "jack" the bike up with a two by four under the fork crown. When the legs are above the ground, you can't hurt those, and the crown is pretty rugged.

Give us an idea of what the stem is so we can see if you need to be worried.
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Old 09-23-08, 07:59 PM
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NICE FIND! ! ! !

Try putting the stem bolt in from the bottom and wiggle the wedge with it. I'd also suggest penetrating oil intstead of rust killer. Hopefully you haven't messed it up already. Rust killer works by converting the rust to a compound that seals and hardens. If it's the same stuff as I used on one of my old trucks you may have just glued the stem in place for all time. But it may be that it didn't penetrate all the way or perhaps YOUR rust killer is a rust remover. They are highly different things.

Anyhow try some penetrating oil and see if that helps. And work the wedge loose from the bottom by using the stem bolt to wiggle it and pry it as best you can.
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Old 09-23-08, 08:54 PM
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Ummm, just checking, you know you have to undo the stem bolt a few turns before hitting it? yes? Sorry if this seems obvious, I've seen too many cases where people have somehow been given only part of the instructions.
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Old 09-24-08, 03:55 AM
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Thanks so far, I am going to try this things and then get back.

This is the bike, original stem I think, a gold coloured thing.

Both the stem and the small cast iron thing seems to be stuck, but I`ll try the thing about

wiggeling from under, and I `ll use a different bolt so I do not destroy the present one.

Only got a carpenters hammer at present, but I put wood ontop of the (unscrewed) bolt and hit it, the wood cracked but nothing else.

My main problem is finding something solid enough to put the bike on when hitting it. My floor mightbe solid, but I do not want to destroy. There is a strong table in the garden I use alot, but I am not sure it is strong enough for this.

Piece of wood under the crown sounds smart, I`we been worried about the Shimano 600 headset also, but I guess I just need to try.

The "rust killer" is penetrating oil, just did not remember what you call it. I guess the brand I am using is not known in your part of the world.

unscrewing the bolt: Yes I did, it is ok that you ask, what is obvius to you might not be for me.

Last edited by badmother; 09-24-08 at 03:56 AM. Reason: 2PelliNg
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Old 09-24-08, 04:22 AM
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You may find this thread of use:

http://www.bikeforums.net/showthread...866&highlight=
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Old 09-24-08, 03:43 PM
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Yes, remember reading this one. I`we been thinking of putting a 2x4 in between the fork legs and bend (straight bar trough the stem), but I am afraid of bending the fork leg.

Also this hairdryer thing is what reminded me about using heat. This is why I was thinking of the candle and gasburner. Again I am worryed about detroying the paint and the gold coloured shimano stem. I am going to try some more tomorrow. Must put more oil and put it upside down tonight.
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Old 09-24-08, 04:43 PM
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I don't think that a candle is a good plan, because aluminium expands more than steel when heated. If penetrating oil doesn't work, try using ammonia- it sometimes removes the result of the galvanic corrosion.

You don't need to worry about the headset, because as long as your hammering force is going through the fork, and not the frame of the bike, no force is put through the bearings. And those shimano threaded headsets are pretty tough.

That's a beautiful find.
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