I was riding my Raleigh Twenty folding bicycle the three blocks from church to a local commuter rail station when the frame collapsed. The handlebars came closer, the saddle tilted forward and the pedals were scraping the ground. I hadn't noticed anything unusual before the sudden failure. I had plans to attend a concert in a town a couple of stops down the line, and I got onto the train with the Twenty anyway.

The train ride gave me time to examine the problem. The nut at the underside of the hinge in the frame had unscrewed or stripped its threads and fallen off in the street. The hinge key held, though I couldn't turn it because it bumped into the frame.

I locked the bike, walked the mile from the train station to the concert. and walked back afterward. I took an Uber ride home. With the walk, I got as much exercise as I would have if I'd ridden home from the train station. Count blessings.

This bicycle is my daily around-town rider, and it's special to me too. It was a project bike which Sheldon mentions that he never finished. Harriet gave it to me after Sheldon died. I took up where Sheldon left off, customizing it with better components.

So, after the frame collapsed I decided to try a repair, and maybe a nut would turn up somewhere.

I looked for the missing nut in the street, but I did not find it. I went to a hardware store and bought a standard 3/8 x 24 TPI nut. It looked right, but it screwed on a few turns and then bound up. I got out a thread pitch gauge and micrometer caliper and measured the stud -- 3/8 inch and 26 threads per inch. Raleigh used 26 TPI where other British bicycle makers used 24 -- headsets, bottom brackets etc., so you'd have to buy genuine Raleigh replacement parts. It's called "brand lock" and we see it with other brands too, especially with chainwheels, but don't get me started about that. Inquiries on Raleigh Twenty fan pages turned up nobody who would sell me the nonstandard nut.

Here is the bike set up to straighten the frame. My son Jacob helped me. We used the jack from a Toyota, a piece of 2 x 3 inch lumber sawed to length, and a couple random objects to prop up the frame on top of our picnic table.

Jacob stabilized the setup while I turned the jack handle. As you can see, we managed to get the hinge completely straight -- while the jack was in place.

Steel is resilient, and once the jack was removed, the hinge opened up partway. Now the hinge key could pass above the frame tube. From this point onward, I might disassemble the frame and finish straightening with the top hinge plate clamped between two strips of wood in a bench vise. There was an easier way. Loosening the hinge key by one turn let us insert a small Allen wrench as a fulcrum to take the hinge past straight using the auto jack. It was just about straight when we released the jack.

Actually it was slightly past straight.

Note that the threaded stud has disappeared. It got pushed up inside the frame tube when we straightened the hinge plate, and was tumbling around loose in there. The stud was not rigidly attached. Actually that is good, because we didn't damage it with the brute force from the jack.

Fishing it out with the threaded end outward isn't too hard. You might work a bit more carefully and avoid this issue.

I sat lightly on the bicycle to remove the reverse bend, but then there was still a slight upward bend at the very rear, which got bent only when being pressed upwards as the frame collapsed. I removed the hinge key and then Jacob and I used an 18 inch adjustable wrench which I had bought to work on bottom brackets to take out the last little bit of bend.

Jacob suggested using a paperclip to hold the threaded stud, so it wouldn't fall back inside the frame. Good idea! But the paperclip would get in the way of reassembly. Cyanoacrylate glue ("Crazy glue") came to the rescue. As it comes out of the tube, it is a thin liquid. It seeped down into the space between the stud and hinge plate. But it didn't accumulate on top and get in the way. It quickly hardens. and makes a strong bond.

In the photo, the stud is pulled out all the way so the unthreaded part sticks up just a bit more than the thickness of the lower hinge plate. This makes it possible to screw a nut down tight and still open and close the hinge. You may need to rotate the stud so it comes all the way out. There is a stop inside which prevents it from turning when rotated correctly.

Where would I find a nut that would fit? Sturmey-Archer used 3/8 x 26 TPI on old Dynohubs, but I don't have one. Maybe on new Sturmey-Archer rotary-shifting hubs? Wait a minute, though, isn't 3/8 x 26 TPI common on many hub axles? A look into the hubs section of Sutherland's Handbook, 6th edition, gave the answer: Indeed, yes. Rummaging around in my parts stash, I found a nut that fit perfectly. I think that it is a nut from a Shimano Nexus rear hub with Rollerbrake. I found an axle washer that would fit fairly snugly around the stud, to press against the top of the stud's flange and keep the hinge free to rotate.

I loosened the hinge key partway so I could carefully lever the hinge down onto the stud without pushing it back into the frame tube. I installed the washer and nut, and there you are. The entire repair was accomplished without even disconnecting the cables to the rear brake and hub. As soon as I had installed the nut and washer, I was able to ride away. This repair proved to be much easier than I had expected, once I figured out what to do.

The hinge plate will have been somewhat embrittled by bending, but it bent back easily and showed no sign of cracking. Its rear is mostly in compression anyway when supported by the stud at the front end. I'll live with it. The threads of the stud appear undamaged. I have some concern that the new nut might unscrew or strip out, and I may use threadlock compound or have it welded in place. While I might possibly disassemble the frame to ship the bicycle in a suitcase or to have the frame refinished. I don't expect to be doing that. At the very least, I'll be checking the nut from time to time.