Those forks sold as replacements often had a ridiculous number of threads, trying to fit all frame sizes with one fork. Those sellers should be hung up by their thumbs!

True, they make a perfectly fine replacement for a small enough frame where the bottom of the threads happens to end up in the right place. But on the biggest frame they fit, the quill is definitely going to be tightening on the threaded part. (And the bigger rider on that bigger frame is probably heavier, stresses bike parts more.).

Imagine you're JRA when the whole stem/bars are suddenly no longer attached by anything but the brake cables. It breaks free with the top of the steerer, headset screwed race and top nut still attached. It'll probably happen when you're hitting the brakes hard on a downhill, so your weight is shifted forward, and there ain't no recovering from that. you're goin' down. If it snaps from hitting a big pot hole then at least you have some chance of riding it to a stop. Luckily the brakes still work, but the bike won't steer great with no upper headset anymore, broken end of the steerer rubbing on the inside of the head tube and flopping around <shiver>.

George Hincapie crashed when his steerer broke near the top, and he was a very experienced pro at the time. Most amateurs will be toast.
"OK we get it Mark, it's bad — enough already!" :deadhorse2: OK, I will drop it now!

Mark B

Too bad you are in the states, I could give you a strong(er) period correct Gitane fork (although in peacock blue) from a tandem with intact filing where only the steerer is not like a spaghetti. Must have been hit by a CAT mining machine.

What Causes This Type Of Damage?
 

The immortal words of the BF resident Gitane expert, one Wolfram Verktyg, instantly came to mind as I saw the graphic details - Ham-fisted Hammersmith.

There were a bunch of decades before the CPSC minimum insertion line.
the extra threads below what the headset could use is not helping, but might well have made one fork fit multiple frame sizes.

way back it was a mechanic's judgement to prevent this or a stem failure. 55mm was the amount I typically made sure was min insertion.

on this fork 55 mm would just be beyond the threads.

assigned risk

That's not beating a dead horse, it's a public service announcement. You've brought up some good points for people - especially Bigfoot's descendants - who may be running an at-risk fork.

Thankfully, I've had the opportunity to put eyeballs on the fork steerer tubes of every bike I own and operate. They all look good, so I've peace of mind in that regard. Overcompensating, yee-hawin' man-boys in lifted trucks, on the other hand, will likely be the death of me if I stay in AZ much longer!

Seriously, I hate those guys.

DD

I was a seller then, or a rep for one, and this was the sole French fork we had, Tange with about 1/3 of the steerer threaded. Cheap generic replacements were much worse in this respect, but with French you don't have many choices.
https://cimg4.ibsrv.net/gimg/bikefor...e1009bff07.jpg

https://cimg9.ibsrv.net/gimg/bikefor...40c30043c9.jpg

Those are very high quality forks, would be awesome for whatever frame size results in all but about 20 mm of threads cut off!

At the max size, with all those threads intact, well let's just say you don't need to worry about your Death Stem, the steerer will kill you before the stem can.

OK I'm deliberately over-stating the likelihood of it breaking. Not all do, but the stakes are very high when one does.

As others have pointed out, the split is from the stem being installed with too little insertion. French steerers are thinner than BSC or Italian by 0.1 mm which doesn't sound like much, but it's already a thin, threaded part. Most of the French forks I have seen only have the flat near the top, but they seemed to have gotten carried away at the Gitane factory that day. Still, it would not have been a problem if the stem had been correctly installed. Practically speaking, this is not a highly stressed area under normal use, as the stem provides significant reinforcement. I would not do this for a customer, but if it were mine I would insert a French stem, tap the bulge out with a hammer, put it together with the stem inserted properly, and ride it without any fear. Even in the unlikely event that a crack would propagate around the thread, which I believe is highly unlikely, a failure would not cause the loss of control one would get should the steerer separate below the stem. Replacing a steerer takes a lot of heat, or a mill and some expensive time. It is not a trivial task.

A steerer crying for one of my stems, ridden as I used to ride them - slammed with a dent in the throat. Puts the nut so far down the bending force is very low and little torque on the bolt is needed. I raced in the '70s. It wasn't 'till the mid '90s I realized how much I could benefit from stems far longer than stock. Still have a few 130s with the scars from the strangler.

Mark, I wish this could be shouted at every aftermarket bike parts importer on this earth.

https://cimg9.ibsrv.net/gimg/bikefor...e708856977.jpg


Those overthreaded "replacement" forks are worthy of being on the top five list for irresponsible parts sold on the bike aftermarket today.

At this point, if I have to replace a fork with a long enough steerer tube, I'll just get the threadless equivalent, slice it to length, and cut the appropriate amount of threads into it.

-Kurt

Classic! I saved that to my Hall of Shame folder of broken bikes'n'parts, it's a keeper.

I believe I sliced off the damaged bit and abused a tap straight into the chrome to make a shorter, but still usable fork out of it. Wasn't a total loss, just a dose of reality about something that, at the time, I hadn't thought about before it happened. ("That, kids, is the value of experience. And mistakes.")

-Kurt

This had me concerned as I'm replacing a fork with one very similar to this with about as much threading. Prior to reading this thread it's not something I had given any thought to as the steerer is not slotted and I was under the misguided thinking that positioning the wedge in the slotted portion was the only issue. I'll be trimming some off the OAL but not that much. Then I remembered the threadless stem adapter I was using goes half way down the steerer tube where I have it set so even with the excessive threading the wedge will be well below the threads. It's one of those extra long ones that was on another bike I took in trade and they were using it to raise the handlebars.

Yes that's a good solution. A bit of extra weight but better than a cracked steerer.

If weight was a concern then I'd have some skinny guy ride it for me. :D :thumb:

If they're going to cut that much thread, do us all a favor and forgo the keyway/flat for the anti-rotation washer. It's not strictly necessary if you use two wrenches when adjusting the headset, and would eliminate the weak spot where these splits occur.

Provided the washer is neither keyed or expecting French-style flatted threads, both of which will split anyway.

Not so sure I trust a wedge on threads either.

-Kurt

Maybe the split stuck out, rubbing inside the head tube. So sombody filed down the bulge and sprayed on a bit of paint.