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FYI: DIY seatpost binder nut for 80s Japanese frames

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FYI: DIY seatpost binder nut for 80s Japanese frames

Old 12-16-20, 11:53 AM
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seypat
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FYI: DIY seatpost binder nut for 80s Japanese frames

I got in a mid 80's frame that uses the rounded nut that sits inside the seatpost clamp. I have 2 frames but only 1 nut/bolt. It's a M6 x 1.0 bolt. 10mm dia/8mm long nut. It has notches cut on one end for a slotted screwdriver. I found some stainless steel coupling nuts the same size, etc on the Zon. They just need the slots cut on one end. They come in a 25 pack. Anyway, if you need one you can order some. Or you can contact me and I will send you out some. I have more than I need.


Last edited by seypat; 12-25-20 at 07:35 PM.
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Old 12-16-20, 11:56 AM
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That's Awesome.
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Old 12-16-20, 02:34 PM
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wasnt this the seatpost bolt arrangement preferred by Miyata? I have kluged around this problem before, using a "tall" allen-headed nut from MTB brake pads to match the bolt. It worked, but I needed to use two allen wrenches to adjust the post -- your solution here is far 'correcter'
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Old 12-16-20, 03:13 PM
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Originally Posted by niliraga View Post
wasnt this the seatpost bolt arrangement preferred by Miyata? I have kluged around this problem before, using a "tall" allen-headed nut from MTB brake pads to match the bolt. It worked, but I needed to use two allen wrenches to adjust the post -- your solution here is far 'correcter'
My Miyata has an Allen head on both sides. My son's Club Fuji has the round nut with a slot.
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Old 12-16-20, 03:40 PM
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This was an unfortunate design that was left off subsequent bikes. When the ear of the lug got bent, it put a stress on the bolt, causing the bolt to break.
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Old 12-16-20, 05:06 PM
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Originally Posted by niliraga View Post
wasnt this the seatpost bolt arrangement preferred by Miyata? I have kluged around this problem before, using a "tall" allen-headed nut from MTB brake pads to match the bolt. It worked, but I needed to use two allen wrenches to adjust the post -- your solution here is far 'correcter'
I have an 85 912 and a 90/91 Team. Both use a hexagon nut.
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Old 12-17-20, 08:05 AM
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Originally Posted by niliraga View Post
wasnt this the seatpost bolt arrangement preferred by Miyata? I have kluged around this problem before, using a "tall" allen-headed nut from MTB brake pads to match the bolt. It worked, but I needed to use two allen wrenches to adjust the post -- your solution here is far 'correcter'
There are pictures of the brake-nut method here:

https://www.bikeforums.net/classic-v...ta-1000-a.html

I agree that the OP's method is a great one--it matches the Miyata original. I wish I'd thought of it. But it's still kind of a pain--the slotted nut doesn't give a very good grip when you want to tighten the bolt. Of course, it's also a pain to have to carry a second allen wrench when using the brake-nut method, but it's arguably even more inconvenient to have to carry a slotted screwdriver.

As wonderful as the old Miyatas were and are, whoever was in charge of the company's binder-bolt division had some strange ideas. The worst setup of all was the one requiring a non-standard hex nut to fit the recess in the lug--break or lose that nut and you're really screwed. I'm eagerly waiting someone to come up with a good solution for that one. I have tried to do that and failed.
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Old 12-17-20, 04:15 PM
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Originally Posted by jonwvara View Post
There are pictures of the brake-nut method here:

https://www.bikeforums.net/classic-v...ta-1000-a.html

I agree that the OP's method is a great one--it matches the Miyata original. I wish I'd thought of it. But it's still kind of a pain--the slotted nut doesn't give a very good grip when you want to tighten the bolt. Of course, it's also a pain to have to carry a second allen wrench when using the brake-nut method, but it's arguably even more inconvenient to have to carry a slotted screwdriver.

As wonderful as the old Miyatas were and are, whoever was in charge of the company's binder-bolt division had some strange ideas. The worst setup of all was the one requiring a non-standard hex nut to fit the recess in the lug--break or lose that nut and you're really screwed. I'm eagerly waiting someone to come up with a good solution for that one. I have tried to do that and failed.
I've collected M6 nuts in a range of hex sizes ranging from 8mm up to I believe 13mm, taken from various bike over the years. It's a proper Collection!

One can file 10mm flats down to fit in the (9mm?) socket of the Miyata frames like my 912.

On many other frames, I've used loctite to secure the round nut inserts, allowing consistent one-wrench adjustment from the drive side.
On my 1984 Stumpjumper Sport, removed the 6mm quick-release skewer from the clamp, drilled and tapped the left ear to M8x1.25, then drilled the right ear 8mm through for a beefy 8mm socket-head screw,

Lots of ways to skin this cat.
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