# Threaded Fork converted to Threadless headset



## Agent319 (Jul 12, 2012)

So why can't I use a threadless headset on a threaded fork? I couldn't answer that question. So I tried it before intalling. I put the threadless headset over the threaded fork and put the threadless stem on and all looked good. So I cut the threaded fork to length put my start nut in and commensed to installing the items. It worked well for me. Test ride was perfect. I can't believe I'm the only one who has thought of this??


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## Bremerradkurier (May 25, 2012)

As long as your stem isn't clamped on the threaded portion, you should be fine; otherwise, hello stress riser!


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## Agent319 (Jul 12, 2012)

Bremerradkurier said:


> As long as your stem isn't clamped on the threaded portion, you should be fine; otherwise, hello stress riser!


Actually the stem is clamped on the threaded portion. I don't foresee any problems there. I may be wrong but a threaded pipe vs a threadless pipe with the same wall diameter will handle same amount of clamped stress as the other.


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## tlg (May 11, 2011)

Is your threaded fork 1" or 1-1/8"?

Why do you think you're the only one who has thought of this?
http://forums.roadbikereview.com/co...-threaded-fork-1-1-8-non-threaded-154586.html


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## tlg (May 11, 2011)

Agent319 said:


> Actually the stem is clamped on the threaded portion. I don't foresee any problems there.


Does the thread extend below the stem? Or is the threaded portion entirely within the clamping area of the stem?

If any of the thread is below the stem, or even close to the bottom, you've got a potential problem. 



> I may be wrong but a threaded pipe vs a threadless pipe with the same wall diameter will handle same amount of clamped stress as the other.


You're kinda wrong. If both ID and OD are the same, and you cut a thread into it, you have less wall thickness.

This would only be true if the wall thickness from the root(bottom) of the thread to the ID was the same. The threaded pipe would need a larger OD or smaller ID. But even then, the threaded pipe would be weaker because as Bremerradkurier mentioned, you have a stress point at the root of the thread.


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## Agent319 (Jul 12, 2012)

tlg said:


> Is your threaded fork 1" or 1-1/8"?
> 
> Why do you think you're the only one who has thought of this?
> http://forums.roadbikereview.com/co...-threaded-fork-1-1-8-non-threaded-154586.html


It is a 1" threaded fork

I checked the forum you listed but all it talks about is changing from Threaded fork to Threadless fork. I'm using my Threaded fork with a Threadless stem.


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## grandsalmon (Jan 18, 2009)

I think you have to judge the steer, case by case (even though they should all be standard). I did a partial same to a tourer years ago. I could only find a fork, fully threaded, so I ran an old WTB by CK headset on it and clamp stem above. Round the world, huge stress, lots off-road, but the STEEL steer tube was too damn stout w the threads. Most will recommend against it theoretically, and I wouldn't let anyone else at it. Personal decision.


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## flattire (Jan 29, 2004)

The type of stress that a threadless stem puts on a steerer tube is way different than the threaded type. Look at it this way, with a threaded system, the tube is cut at the top of the headset. There is no leverage on the steerer tube. With the threaded, you have the force of the stem both clamping on the tube and there is leverage on the section. An unthreaded tube can take that stress, but when you cut threads in it, you significantly compromise the strength. There is a very real risk this steerer tube will crack just below the stem, if you're lucky it won't break clean off when you are flying down a steep hill and hit a bump. Hello stress riser, indeed.


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## CleavesF (Dec 31, 2007)

You can always fill the threads with epoxy puddy, sand it out to make it smooth... 

Steel forks will not give out catastrophically like alumninum will. (or carbon). You will know when your fork is about to fail with steel.


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## tlg (May 11, 2011)

Agent319 said:


> It is a 1" threaded fork


So you got a 1" threadless headset?


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## tlg (May 11, 2011)

CleavesF said:


> You can always fill the threads with epoxy puddy, sand it out to make it smooth...


 That will do nothing to add strength.


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## Agent319 (Jul 12, 2012)

tlg said:


> So you got a 1" threadless headset?


Yes I have a 1" threadless headset with a threadless stem attached to a threaded fork.


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## Agent319 (Jul 12, 2012)

tlg said:


> Does the thread extend below the stem? Or is the threaded portion entirely within the clamping area of the stem?
> 
> If any of the thread is below the stem, or even close to the bottom, you've got a potential problem.
> 
> ...


The threads extend below the stem.


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## Agent319 (Jul 12, 2012)

grandsalmon said:


> I think you have to judge the steer, case by case (even though they should all be standard). I did a partial same to a tourer years ago. I could only find a fork, fully threaded, so I ran an old WTB by CK headset on it and clamp stem above. Round the world, huge stress, lots off-road, but the STEEL steer tube was too damn stout w the threads. Most will recommend against it theoretically, and I wouldn't let anyone else at it. Personal decision.


If this fork handled it and this guy is still alive then I think Myth Busters would call this myth busted that a threaded fork can't handle a threadless stem


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## Agent319 (Jul 12, 2012)

tlg said:


> Does the thread extend below the stem? Or is the threaded portion entirely within the clamping area of the stem?
> 
> If any of the thread is below the stem, or even close to the bottom, you've got a potential problem.
> 
> ...


Yes I agree that a threaded tube is weaker than a non-threaded tube but what amount of stress in Flbs will this have on it during bike riding. I can't believe the sheer stress will be that much.


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## tlg (May 11, 2011)

Agent319 said:


> Yes I have a 1" threadless headset with a threadless stem attached to a threaded fork.


Nothing wrong with that then.



Agent319 said:


> The threads extend below the stem.


As mentioned by several people... not a great idea. 



> If this fork handled it and this guy is still alive then I think Myth Busters would call this myth busted that a threaded fork can't handle a threadless stem


That proves ABSOLUTELY nothing. You've come to a "scientific" conclusion based on a single anecdotal story on the internet? Adam and Jamie would be ashamed.

Do you have the same fork? Do you ride the same conditions? Are you the same weight?


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## tlg (May 11, 2011)

Agent319 said:


> Yes I agree that a threaded tube is weaker than a non-threaded tube but what amount of stress in Flbs will this have on it during bike riding. I can't believe the sheer stress will be that much.


You're welcome to believe there isn't much stress on a steerer tube.


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## Bremerradkurier (May 25, 2012)

Agent319 said:


> Yes I agree that a threaded tube is weaker than a non-threaded tube but what amount of stress in Flbs will this have on it during bike riding. I can't believe the sheer stress will be that much.


Think of all the fatigue cycles working on the very small area of the thread valley right at the bottom of your stem during a ride of just ten miles, remembering that the inputted force is at least your upper body weight working with a minimum lever length of 4" (bar tops, 100mm stem) to as much as 9" (brake hoods, 120mm stem).


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## tlg (May 11, 2011)

Bremerradkurier said:


> Think of all the fatigue cycles working on the very small area of the thread valley right at the bottom of your stem during a ride of just ten miles, remembering that the inputted force is at least your upper body weight working with a minimum lever length of 4" (bar tops, 100mm stem) to as much as 9" (brake hoods, 120mm stem).


Then throw in the impact force from hitting a pothole. It will easily spike the forces up 5x-10x.
There's no suspension on a road bike and the tires are at a high PSI. All those forces drive right up through the fork and stem.

I use to work in the railroad industry. We had to design for massive G forces. The bearings on a train car can see up to 20 G's just from a little bump in the tracks. It's amazing what happens when you don't have a suspension.


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## foto (Feb 7, 2005)

lol, this is such a bad idea...

I am pretty sure the wall thickness on threaded steer tubes are different than threadless, btw...

Love how people will risk their lives to save the $40 or whatever...


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## Bremerradkurier (May 25, 2012)

foto said:


> lol, this is such a bad idea...
> 
> I am pretty sure the wall thickness on threaded steer tubes are different than threadless, btw...
> 
> Love how people will risk their lives to save the $40 or whatever...


The idea isn't all that bad, and plenty of shops out there probably have old stock threaded forks for circus freak sized 63cm + frames preserved under an inch of dust that could easily be cut below the threads and used in threadless headsets.

Remember, a lot of the change to threadless steer tubes in the bike industry was due to how easy it made fork inventory-one size for all size frames vs. having to match the threaded length to each range of frame sizes.


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## foto (Feb 7, 2005)

Bremerradkurier said:


> The idea isn't all that bad, and plenty of shops out there probably have old stock threaded forks for circus freak sized 63cm + frames preserved under an inch of dust that could easily be cut below the threads and used in threadless headsets.
> 
> Remember, a lot of the change to threadless steer tubes in the bike industry was due to how easy it made fork inventory-one size for all size frames vs. having to match the threaded length to each range of frame sizes.


good point, but not really what the discussion was about. The OP is clamping a threadless stem to the threads of a threaded fork.

This is a bad idea. Would make more sense to me to get a shop to cut some more threads in the steerer, cut off the top, and use a quill stem. But that's me. I don't like worrying about whether my handlebars are going to come flying off when I am riding. Personal opinion here...

It would look a lot better, too.


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## foto (Feb 7, 2005)

CleavesF said:


> You can always fill the threads with epoxy puddy, sand it out to make it smooth...
> 
> Steel forks will not give out catastrophically like alumninum will. (or carbon). You will know when your fork is about to fail with steel.


Haha! Steel will not fail catastrophically? Are you suuuuuure?


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## Agent319 (Jul 12, 2012)

foto said:


> lol, this is such a bad idea...
> 
> I am pretty sure the wall thickness on threaded steer tubes are different than threadless, btw...
> 
> Love how people will risk their lives to save the $40 or whatever...




In this "throw away society" I'm just doing my best to recycle. 



I risk my life everyday just getting out of bed and driving to work.


Heck, now that you mention risk I'm going to throw a quote out there from the movie "Diliverance"... "I've never been insured in my life. I don't believe in insurance... there is no risk."


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## tlg (May 11, 2011)

CleavesF said:


> Steel forks will not give out catastrophically like alumninum will. (or carbon). You will know when your fork is about to fail with steel.


That is officially the worst thing I've ever read on this site.

If the stress exerted on the steel exceeds the strength of the steel, while you are riding, you will achieve catastrophic failure.


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## tlg (May 11, 2011)

foto said:


> good point, but not really what the discussion was about. The OP is clamping a threadless stem to the threads of a threaded fork.


The act of clamping on the threads isn't a problem. The forces of the clamp on the threads isn't a big deal. And sufficient to hold the stem onto the steerer, which is all it does.
The problem is the thread outside (below) of the clamping area. All the moment forces, which will be the greatest forces, will be right at a nice sharp stress point. Which will also be at the thinnest point of the steerer tube.


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## JCavilia (Sep 12, 2005)

I'm all for recycling, but I agree with all those who say this is a very dumb idea. I hope you are lucky and don't get hurt. There are a lot of things on a bike where a catastrophic failure creates only moderate danger. Stem/steerer interface is not one of those.

Why did you want to do this anyway? What advantage of threadless stems did you think you were gaining? Good old threaded headsets and quill stems work just fine.

Best of luck.


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## Agent319 (Jul 12, 2012)

JCavilia said:


> I'm all for recycling, but I agree with all those who say this is a very dumb idea. I hope you are lucky and don't get hurt. There are a lot of things on a bike where a catastrophic failure creates only moderate danger. Stem/steerer interface is not one of those.
> 
> Why did you want to do this anyway? What advantage of threadless stems did you think you were gaining? Good old threaded headsets and quill stems work just fine.
> 
> Best of luck.


Here is why I'm doing it. I have a 1993 R700 Cannondale frame I picked up for $36 dollars and I want to rebuild this bike for less than $400. I have a carbon/steel threaded fork but like the looks of the threadless steem. So if I can use this fork safely then all the better to help me keep this under budget. 

I agree that this may be a little to dangerous and that's why I put this thread out there and if I decide it's to dangerous I still have the quill stem. Just wanted some opinions


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## foto (Feb 7, 2005)

tlg said:


> The act of clamping on the threads isn't a problem. The forces of the clamp on the threads isn't a big deal. And sufficient to hold the stem onto the steerer, which is all it does.
> The problem is the thread outside (below) of the clamping area. All the moment forces, which will be the greatest forces, will be right at a nice sharp stress point. Which will also be at the thinnest point of the steerer tube.


um, I get it. And I would add if there are threads under the stem, like in between the top and bottom of the stem, they will be experiencing a moment also.

All it could take would be a nice pothole to crack the top off. That would be really not hilarious.


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## foto (Feb 7, 2005)

Agent319 said:


> Here is why I'm doing it. I have a 1993 R700 Cannondale frame I picked up for $36 dollars and I want to rebuild this bike for less than $400. I have a carbon/steel threaded fork but like the looks of the threadless steem. So if I can use this fork safely then all the better to help me keep this under budget.
> 
> I agree that this may be a little to dangerous and that's why I put this thread out there and if I decide it's to dangerous I still have the quill stem. Just wanted some opinions


To be safe, fou can use a threaded headset with a spacer under the top nut and then a quill adapter for your threadless stem if you must use a threadless stem.


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## Agent319 (Jul 12, 2012)

foto said:


> To be safe, fou can use a threaded headset with a spacer under the top nut and then a quill adapter for your threadless stem if you must use a threadless stem.



I didn't know there was such a think. I'll check that out.


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## foto (Feb 7, 2005)

this is what you want.

https://www.google.com/search?q=qui...r_cp.r_qf.&fp=a475d8eefb2f6f&biw=1366&bih=677


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## T K (Feb 11, 2009)

Tuesday I had to call 911 for myself as I lay face down in some gravel. I thought I was going to die there and never see my kids again. I was up on a hill by myself with nobody around. Thank goodness I was able to grab my cell phone. I have been lying around the house since then thinking about what might have happened. Scary thoughts.
Please do not risk your life to save a few bucks.
It may be all jokes now, but smashing your face into the ground, busting teeth and getting stitches in your lip is no fun. I've done that, don't want to do it again.


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## jneilt (Aug 11, 2012)

quill adapters work wonderfully, so do 1" non-threaded forks.

let me know how that threadless HS works long term with a threaded fork. You could learn the ultimate in recycling.


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## Agent319 (Jul 12, 2012)

foto said:


> this is what you want.
> 
> https://www.google.com/search?q=qui...r_cp.r_qf.&fp=a475d8eefb2f6f&biw=1366&bih=677


After reading some horor stories I believe I'll be getting one of these.


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## Jslip (Jul 25, 2012)

I've done it without problems twice, but not by just clamping onto the threads - For all the reasons listed above. I took a few precautions.

1. I used a wire wheel to clean all the threads, then washed away any gunk with acetone. Let it dry.

2. Whipped up a batch of JB Weld, and filled in all the valleys of the threads with it. Let it dry.

3. Filed/sanded the JB weld so it was flush with the threads.

4. Repeated steps 2-3 for any gaps that appeared when drying.

5. When reassembling, I inserted a compression plug instead of a star-fangled nut. This helps to balance out the forces on the steerer tube from the stem (inward vs. outward)

6. Rode bike like normal.

I first did this in 2001, and it has worked fine. Have repacked and reassembled without issue (or noise). But no manufacturer would okay this, I'm sure. Do it at your own risk (which I consider to be minimal). Enjoy the $100 you saved on a fork.


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## T K (Feb 11, 2009)

the Jb weld works great as bondo but I doubt it helps out with making it much stronger.


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## Jslip (Jul 25, 2012)

Well, the advantage to JB is that with the steel fragments in it, it has lower compressibility than most other epoxies. I wouldn't try to build a whole steerer out of it, but I'm pretty sure it lessens the flex at narrow points in the threads by preventing the threads from pushing together on the compressing side as they pull apart on the opposite (tension) side.

For sure it won't be as strong as a fully forged threadless steerer, and I wouldn't do it if the stem clamped only on the JB/threads, but for 1/2 the clamp area, it seems to be okay.


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## gordy748 (Feb 11, 2007)

I read something like this on one of Leonard Zinn's columns recently. He basically said it was a bad, bad idea. To help with the consequences of what you're doing, try to find the Paris-Roubaix footage where George Hincapie broke his steerer tube on one of the cobbled sections.


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## T K (Feb 11, 2009)

I just don't understand why to save 100 bucks someone would do this. I've had twice a steerer tube break and landed on my face. It is not fun.


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## CleavesF (Dec 31, 2007)

tlg said:


> That will do nothing to add strength.


The suggestion wasn't to add strength, it was to make it "even"



tlg said:


> That is officially the worst thing I've ever read on this site.
> 
> If the stress exerted on the steel exceeds the strength of the steel, while you are riding, you will achieve catastrophic failure.


I like how you bust out words from material science in the wrong ways, like strength and stress. 

Anyways, call me whatever names, you obviously don't know anything about the properties of steel.

and old supporting evidence: http://forums.roadbikereview.com/bikes-frames-forks/any-advantages-steel-bikes-12382.html


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## Cinelli 82220 (Dec 2, 2010)

Agent319 said:


> I can't believe I'm the only one who has thought of this??


I've had a steel threaded fork/threadless headset on my commuter mountain bike for about 15 years.
Brodie Gatorblade fork, steel steerer.
Race Face Aheadset.
Syncros Cattlehead stem.


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