replacement seatpost binder bolt Miyata 1000?
 

The binder bolt for my '82 Miyata 1000's seatpost kept coming loose and it was never easy to tighten. Here's some pictures of the bolt and the seat tube. You need something like a flathead on the nut end and allen on the bolt. But the bolt pushes into the flathead as you try to hold the nut in place.
I replaced it with a new bolt but it's ugly and external. I really would like something closer to the original that fits neatly into the seat tube similar to the way it's cleanly designed. Not sure where/what to look for.

http://i24.photobucket.com/albums/c1.../seattube1.jpg
http://i24.photobucket.com/albums/c1.../seattube2.jpg
http://i24.photobucket.com/albums/c1...inderbolt2.jpg
http://i24.photobucket.com/albums/c1...inderbolt1.jpg

Didn't know if this was a question best for CV folks or the mech forum. Let me know, don't want to cross-post.

thanks,
-Michael

I'm not positive but it looks like the ridges on the frame were made to hold the nut in place while you adjust the bolt. Usually, one side of the binder bolt is held in place by some feature on the frame so you shouldn't need to hold it while you adjust the other side. I think you need a special nut with mating ridges that fits the hole. I don't think it's a common design as I haven't seen one like that before but maybe someone here has a nut that would work. There are other readily available bolt designs around but you'd have to modify the 'fixed' side of hole in the frame to make them work.

I had the same issue when restoring my 1981 One Thousand. I just came up with a small washer that fit the "Allen" side that was of the same diameter ....... this kept the bolt from screwing in as deep, allowing a screwdriver to stay in place on the opposite side. Worked perfect.

http://www2.snapfish.com/snapfish/sl...360_161597360/

Also, my 1981 model does NOT have the knurled edges on either side like yours, and I'm not quite sure why there would be a difference in manufacturing being we each have the same bolt design. Where you have the knurling, my bike has nicely rounded and painted edges. Could be the 1982 version used a different style bolt.

I had a feeling that would become confusing. The knurled ridges are from the aftermarket bolt I picked up at an LBS. It grabs the seat post housing for the binderbolt from the outside and created those impressions in the paint.

I'll try your idea with the washer. And probably use some blue loctight. Gorgeous restoration, BTW

My '84 Miyata 210M has a notch that aligns with the nut inside the housing and holds it in place while tightening. It's really the only feature on what's otherwise a fairly low-end Miyata design.

Thanks guys,
-Michael

I'm rousing this thread from a five-year coma because I recently came up with what seems to me like a fairly neat solution to the Miyata 1000 seatpost binder-bolt problem, since the fitting on the seat lug is such that standard binder bolts don't fit.

http://bikeforums.net/attachment.php...hmentid=457617http://bikeforums.net/attachment.php...hmentid=457618http://bikeforums.net/attachment.php...hmentid=457619http://bikeforums.net/attachment.php...hmentid=457620http://bikeforums.net/attachment.php...hmentid=457621http://bikeforums.net/attachment.php...hmentid=457622

The pictures pretty much tell the story. A standard M6 stainless-steel socket-head bolt from the hardware store just fits the lug. A 20 mm bolt is a couple of mm too long, so I used a 16 instead. It would have gotten a little more thread engagement by filing or grinding the 20 mm bolt down to about 18 mm, but the 16 seems fine. The original cylindrical Miyata nut was slotted for a screwdriver blade. That never worked very well (see previous posts in this thread), so in its place I used a mounting nut pilfered from a set of Jaguar brake pads. It's a perfect slip fit in the recess on the seat lug.

The result is a functional improvement on the original, since now you can use an allen wrench on both the nut and bolt. It also looks good, at least to me to me--more like something that could have come from the factory than the kludgy appearance you get from using a longer bolt, washers, and a conventional nut.

Also included is a gratuitous shot of the bike itself, which I just finished building up but have not yet ridden. You can also see the woodpile to my sauna, part of the sauna itself, and--in the first picture--some of my laundry hanging on the clothesline.

Thanks for reviving this thread, because I just hit the same issue! I've now ordered that exact set of brake pads just ​for the allen nut :)

You're welcome. I found it to be a really satisfying solution--an improvement on the original in some ways.

JV

I also did this for my Panasonic DX5000. It's a great solution.
--John

Good looking sauna; the bike's not bad looking either, ;).