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Seatpost clamp bolt for Ron Cooper

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Seatpost clamp bolt for Ron Cooper

Old 07-13-20, 10:42 AM
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Glengarry
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Seatpost clamp bolt for Ron Cooper

Hi all, I have a Ron Cooper frame, I think 80s though can't be sure.
It has a threaded seatpost clamp which I'm trying to find a bolt for. It's close to M8 but doesn't fit various M8 bolts I've tried, so I'm guess it's an imperial thread. Could anyone help me narrow it down so I can order the right thing?
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Old 07-13-20, 11:09 AM
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5/16" is just slightly under 8 mm, and the usual UNF thread is 5/16-24. You might be able to determine the thread pitch of the frame by using a bent wire and a dial caliper. Or just buy a 5/16-24 and 5/16-18 screw each, and see if either fits.
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Old 07-13-20, 11:14 AM
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The treading used on binder bolts on British frames of the classic era is 5/16" X 22 BSF (British Standard Fine). These have threads that are a little finer (more teeth per inch) than British standard Whitworth. I don't know of an American supplier for these bolts. I got my tap from England. The socket wrench size you need to use on the socket head bolt that fits into the binder is 7/32". Even though American and metric socket wrenches kind of work, I wouldn't use them because their smaller size will round the socket a bit if any pressure is applied.
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Old 07-13-20, 11:21 AM
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Originally Posted by Glengarry View Post
Hi all, I have a Ron Cooper frame, I think 80s though can't be sure.
It has a threaded seatpost clamp which I'm trying to find a bolt for. It's close to M8 but doesn't fit various M8 bolts I've tried, so I'm guess it's an imperial thread. Could anyone help me narrow it down so I can order the right thing?

I'm sorry I should not do this to a new member... first, WELCOME!
Now...Sorry, Impossible bolt to find. Please send useless frame to: E Smith, Box 1000, Northvale Post Office, Northvale NJ, 07647

Back to regular scheduled programming. I don't know the answer. When you have 10 posts, post a picture of the seat cluster. That will help if not already answered. I have a Witcomb with a threaded bolt, which i can get measured, if they are similar. Please post pics (many) of your Cooper, BTW, there is a RC appreciation thread in C&C. Lots of fans here.... Edit: Trust Doug's answer...
p
1974 Witcomb Track Bike
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Old 07-13-20, 11:31 AM
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This may be blasphemy to some but...

You could always drill out the threads and tap in a helicoil of a more common size.
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Old 07-13-20, 11:38 AM
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Originally Posted by Narhay View Post
This may be blasphemy to some but...

You could always drill out the threads and tap in a helicoil of a more common size.
Please don't....
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Old 07-13-20, 11:42 AM
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Originally Posted by Charles Wahl View Post
5/16" is just slightly under 8 mm, and the usual UNF thread is 5/16-24. You might be able to determine the thread pitch of the frame by using a bent wire and a dial caliper. Or just buy a 5/16-24 and 5/16-18 screw each, and see if either fits.
Thanks, I'll try this!
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Old 07-13-20, 11:43 AM
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Originally Posted by Narhay View Post
This may be blasphemy to some but...

You could always drill out the threads and tap in a helicoil of a more common size.
The brake mounts have already been drilled out for modern recessed fittings, so it wouldn't be the first blasphemy, but I'm hoping this will be easy to solve with some of the advice on here. Thanks.
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Old 07-13-20, 11:44 AM
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Shipping takes so little time. Ron Cooper built that frame. By himself. Alone. I did mine over because 2 tubes were smashed.
What size is it, and where are you located? I'll trade some pretty great frames for it if you're interested. I'm kinda a fan of his work.
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Old 07-13-20, 11:51 AM
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Glad to see your post. Yep, 7/32 Allen key, I'd be willing to bet Doug is correct with the rest too.

1974 Witcomb seatpost bolt w/ 7/32 Allen wrench.
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Old 07-13-20, 12:20 PM
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Originally Posted by Glengarry View Post
Thanks, I'll try this!
While it will be fairly cheap to find a 5/16-24 screw and try the thread, my guess is that Doug Fattic knows better. FWIW, Fastenal sells 5/16-22 socket head cap screws in black oxide finish (not particularly corrosion-resistant) by the piece:
https://www.fastenal.com/product/fas...FamilyId=30892
They appear to have 1" and 1-1/2" length. Pricey at over $10, but maybe an answer.
So does a joint called RC Fasteners in AZ, though they don't list prices:
https://www.rcfastener.com/516-22x11...oyblack/813238
Also Empire Bolt & Screw, though they don't provide sufficient information, IMO.

Last edited by Charles Wahl; 07-13-20 at 12:28 PM.
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Old 07-13-20, 12:43 PM
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Glengarry, just for reference on who I am, I am an American that learned how to build bicycle frames in England in 1975. Before that time I had ordered several British frames from well known builders like Bill Hurlow and Hetchins. They all used 5/16" X 22 teeth per inch bolts. In my case they were 1" long. I'm very familiar with what bolt you need. Sometimes if the binder stands alone (without the seat stays coming into it - like the picture of the frame from Last ride 76) the bolt might be shorter. In any case if you get a 1" socket head cap screw (that is the term you use when doing a google search), it can be cut a little shorter or stick out a bit.

You do NOT want to try using a metric or American bolt! There are suppliers of British thread bolts in the US. Here is one in Lyons NY: https://britishfasteners.com/socket-...x-1-2260z.html. They cost 80 apiece. They have them in stock. You are asking for a 5/16" X 22 BSF socket head cap screw that is 1" long (that length does not include the length of the head, only the length of the treads).
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Old 07-13-20, 01:26 PM
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Originally Posted by Glengarry View Post
Thanks, I'll try this!
Strongly encourage you to heed Mr. Fattic's advise, he has fixed, repaired and sorted out more of these than most will ever see.

Patience is key here, do no harm.
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Old 07-14-20, 11:44 AM
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Originally Posted by Doug Fattic View Post
Glengarry, just for reference on who I am, I am an American that learned how to build bicycle frames in England in 1975. Before that time I had ordered several British frames from well known builders like Bill Hurlow and Hetchins. They all used 5/16" X 22 teeth per inch bolts. In my case they were 1" long. I'm very familiar with what bolt you need. Sometimes if the binder stands alone (without the seat stays coming into it - like the picture of the frame from Last ride 76) the bolt might be shorter. In any case if you get a 1" socket head cap screw (that is the term you use when doing a google search), it can be cut a little shorter or stick out a bit.

You do NOT want to try using a metric or American bolt! There are suppliers of British thread bolts in the US. Here is one in Lyons NY: [link] They cost 80 apiece. They have them in stock. You are asking for a 5/16" X 22 BSF socket head cap screw that is 1" long (that length does not include the length of the head, only the length of the treads).

Thanks, I really appreciate you taking the time to respond. I've ordered myself a bolt per your suggestion and I'll let you know how I get on.
(Sorry for delayed response btw, I was only allowed five posts in the first 24 hours)
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Old 07-14-20, 11:46 AM
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Originally Posted by Last ride 76 View Post
Shipping takes so little time. Ron Cooper built that frame. By himself. Alone. I did mine over because 2 tubes were smashed.
What size is it, and where are you located? I'll trade some pretty great frames for it if you're interested. I'm kinda a fan of his work.

(delayed response as I wasn't allowed to post more than five times in the first 24hrs)
Thanks for your interest and advice! It's 21.5" but I'm pretty attached to it I'm afraid. I'll make sure to post some pics when I can. It's good to know people around the world appreciate his work.
As a fan, you've probably found this already, but just in case you haven't, Ron was interviewed for The Bike Show radio program/podcast back in 2010. I can't post a link as a newbie, but if you google 'the bike show ron cooper' you'll find it

Last edited by Glengarry; 07-14-20 at 02:42 PM.
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Old 07-14-20, 12:05 PM
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Originally Posted by Glengarry View Post
(delayed response as I wasn't allowed to post more than five times in the first 24hrs)
Thanks for your interest and advice! It's 21.5" but I'm pretty attached to it I'm afraid. I'll make sure to post some pics when I can. It's good to know people around the world appreciate his work.
As a fan, you've probably found this already, but just in case you haven't, Ron was interviewed for The Bike Show radio program/podcast back in 2010. I can't post a link as a newbie, but if you good 'the bike show ron cooper' you'll find it
THX, been there. Wish I'd had him rebuild mine, but could not afford shipping in 76...
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Old 07-14-20, 12:39 PM
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Aye, Ron Coopers are pretty special!

When I'm doing framebuilding, I try to think about his words in that interview.
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Old 07-14-20, 01:18 PM
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A Picture Is Worth A Thousand Words, Especially If It's Of The Seat Stay Array?

Originally Posted by Glengarry View Post
Thanks, I really appreciate you taking the time to respond. I've ordered myself a bolt per your suggestion and I'll let you know how I get on.
(Sorry for delayed response btw, I was only allowed five posts in the first 24 hours)
If you post photos to the Gallery section of this site, in an album, one of us will promptly post them here for you!

A pic or two of your seat stay binding ears, and of the drive side of your Ron Cooper, would be absolutely fabulous.
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Old 07-14-20, 02:41 PM
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Originally Posted by machinist42 View Post
If you post photos to the Gallery section of this site, in an album, one of us will promptly post them here for you!

A pic or two of your seat stay binding ears, and of the drive side of your Ron Cooper, would be absolutely fabulous.
I've put up an album - if anyone can work out what the tubing is based on a (very) partial decal, have a look!
Can't post a link as a newbie, but it's at --bikeforums.net/g/album/18502000
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Old 07-14-20, 02:59 PM
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Pic Assist









(Remnants of a Columbus sticker?)
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Old 07-14-20, 03:04 PM
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It's all modern Shimano components, I know not to everyone's taste... but it rides good!
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Old 07-14-20, 03:07 PM
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Continuing Picture Assistance



Would you please post some photos of the underside of the bottom bracket, and the underside of the chainstay, and the dropouts?
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Old 07-14-20, 04:03 PM
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Originally Posted by machinist42 View Post

Would you please post some photos of the underside of the bottom bracket, and the underside of the chainstay, and the dropouts?
Added them to the gallery - are they what you had in mind? Occurs to me I have no idea what the serial number means - I've tried some googling without much success.
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Old 07-14-20, 05:14 PM
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Hmmmm.









(I am not familiar with that serial number format in connection with Ron Cooper.)

May I suggest taking photographs outside on a sunny day, but in the shade, and removing the wheels? I'd like to see the way the stays were finished.
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Old 07-16-20, 09:50 AM
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Originally Posted by Doug Fattic View Post
The treading used on binder bolts on British frames of the classic era is 5/16" X 22 BSF (British Standard Fine). These have threads that are a little finer (more teeth per inch) than British standard Whitworth. I don't know of an American supplier for these bolts. I got my tap from England. The socket wrench size you need to use on the socket head bolt that fits into the binder is 7/32". Even though American and metric socket wrenches kind of work, I wouldn't use them because their smaller size will round the socket a bit if any pressure is applied.
Very happy with my new bolt and 7/32 wrench - thanks so much for your advice. Photos added to gallery.
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