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How to cinch '82 Miyata Seatpost Bolt

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How to cinch '82 Miyata Seatpost Bolt

Old 02-17-19, 09:30 PM
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How to cinch '82 Miyata Seatpost Bolt

The nut isn't keyed and turns with the bolt. I filed the bolt down in length so I could get a coin on the nut side, but that doesn't work to my satisfaction. And that requires a third hand to hold up the seatpost in the process.

JB Weld?



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Old 02-17-19, 11:00 PM
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Easy, just tape the seatpost in the right position to the seat lug, and you will have two hands to work the bolt with....
Tighten, remove tape, and you are done!
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Old 02-17-19, 11:04 PM
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That sure looks like a chain ring nut. Perhaps a nut holder for chain rings would work.
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Old 02-17-19, 11:25 PM
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Two good ideas: tape and a better tool on the nut side. It would be nice to acquire an allen keyed nut, so I could just use two 5mm wrenches.
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Old 02-18-19, 12:22 AM
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I have a big-ass flat blade screw driver that would be perfect for that application. Chain ring tool would be my second thought/
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Old 02-18-19, 06:02 AM
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I've made several such tools by a) creating a bin of odd steel bits "too small to throw away". As in this case pick one that's his third carbon spring steel or an old tool or piece of banding then b) cut to width and grind a notch in each edge, leaving a nub in the center to key into the nut. Sort of a DIY chain ring nut tool.

But ifn it were me, I'd try to find or fit a classic dual ended pinch bolt there. I have found that there is no better design than the dual ended (hex key socket on each end) steel pinch bolt assembly. And regardless of the condition of the key on the NDS end or the notch in the frame, I always use two hex keys. I've seen too many of those notches stripped out by folks only using a hex key on the DS bolt head. I never understood the need for the wee bit of confidence that key/notch idea delivered. Doomed to failure.
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Old 02-18-19, 11:55 AM
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^ Thanks for the ideas, guys.
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Old 02-18-19, 12:35 PM
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A longer bolt, stacked spacers and a standard 8 or 10 mm nut will fix that. Done it a few times on those old Miyatas. Beautiful frames.
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Old 02-18-19, 01:14 PM
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Originally Posted by Prowler View Post
I've made several such tools by a) creating a bin of odd steel bits "too small to throw away". As in this case pick one that's his third carbon spring steel or an old tool or piece of banding then b) cut to width and grind a notch in each edge, leaving a nub in the center to key into the nut. Sort of a DIY chain ring nut tool.

But ifn it were me, I'd try to find or fit a classic dual ended pinch bolt there. I have found that there is no better design than the dual ended (hex key socket on each end) steel pinch bolt assembly. And regardless of the condition of the key on the NDS end or the notch in the frame, I always use two hex keys. I've seen too many of those notches stripped out by folks only using a hex key on the DS bolt head. I never understood the need for the wee bit of confidence that key/notch idea delivered. Doomed to failure.
Theoretically, as long as you don't grease the keyed side at all, friction will keep it from turning while you tighten the other side...just like chainring bolts are supposed to work (note the "supposed", there). The key won't stop over-torque-ing from moving it, but for normal use it should be okay.
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Old 02-18-19, 01:26 PM
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Some seatpost nuts have a splined section that is a press fit on the frame.
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Old 02-18-19, 02:54 PM
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^ Ooh, that would be perfecto.

I like that this bolt all fits inside the lug, so I'm trying to keep that bit of the sleek originality.

In the pic, the nut does look like one used on a chainring. It's not, though, and is far thicker and without a lip.
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Old 02-18-19, 05:12 PM
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Had a Univega Super Strada set up the same way. I would tighten it just enough to hold the seatpost in place (it's a fine line) with my left thumb on the bolt and fingers keeping the post more or less in position while the right hand used the hex wrench. Once things were where I needed them to be I switched to a wide screwdriver as mentioned above and was able to tighten appropriately.

It never failed to irritate.
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Old 02-18-19, 07:37 PM
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Originally Posted by Fahrenheit531 View Post
Had a Univega Super Strada set up the same way... It never failed to irritate.


Thanks. Glad I'm not alone. I was sorta scared I was missing something obvious. I mean, how was this acceptable in the first place?
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Old 02-18-19, 08:49 PM
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Originally Posted by SurferRosa View Post
The nut isn't keyed...




Wrong nut? Is the seat lug inset hex stripped? I have an '83 professional with the same seatlug.
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Old 02-18-19, 11:30 PM
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Originally Posted by Mr. 66 View Post
I have an '83 professional with the same seatlug.
Sounds like you have a different nut that stays in place somehow?
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Old 02-19-19, 10:39 AM
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Originally Posted by SurferRosa View Post
Sounds like you have a different nut that stays in place somehow?
Here's what I have. It looks normal but is deeper than a reagular nut with the added depth barreled.

Last edited by Mr. 66; 02-19-19 at 10:43 AM.
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Old 02-19-19, 12:22 PM
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Originally Posted by Mr. 66 View Post
Here's what I have.
Ok, thanks for sharing that. Yours is flatted on the nds. That keeps the flatted nut in place.
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Old 02-19-19, 04:23 PM
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I used a tiny, tiny bit of JB Weld on the nut, just like i was greasing it. Then waited ten hours. I didn't think it would hold, but it works great. I'm pretty sure I could hammer it out if needed, but I hope it's there for the dur.
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Old 09-29-19, 07:46 AM
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I'm encountering the same thing on an '83 Miyata 1200 I recently purchased. How could the factory have been so blind to this? I figured a wide flat tip screwdriver would do the trick also, but the bolt protrudes just enough that that doesn't work.

I'll try spacers, and possibly a lock nut washer if I can find one to fit and see if that works.
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Old 09-29-19, 08:07 AM
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Maybe you coul sneak a small star washer in there...
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Old 09-29-19, 08:12 AM
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On the Univega I bought last spring I used a 6mm Allen recessed brake nut.
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Old 09-29-19, 08:39 AM
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UNREAL! You can't make this up.

For whatever reason, in my standard tool box, I kept a new 10'' long piece of rubber vaccuum hose from a 1986 Trans Am I had a looong time ago. After determining it was a bit to wide, I cut off a piece about 1/16'' long. I then cut off about a 1/8'' piece off the circumference and wedged it in so it made a nice tight fit on the nut side.
I then put the bolt through pushing it past the rubber "washer" I made and threaded on the nut. I used a screwdriver in the groves of the nut to hold it in place, and voila!! I nice, tight fit!!! Seatpost is a solid as can be!

Moral of the story...don't throw anything out, lol!!

Fred
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