Shorten a steer tube

Jun 20, 2020
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I have a number of front forks lying around here. These are aperfect fit for my 60's frames, but when I sized one of these up for my 40's Huffman it was too long. I am no fabricator. Is there a way to remove the steer tube from the fork, saw off to the desired length, and reattatch?
 
Jun 20, 2020
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Sounds like a plan! I'd be going from 6 3/4" to 6 3/8". Looks like removing 3/8" leaves plenty of thread.
Thanks!
... of course I plan to measure a few more times before cutting.
Seems like this could be done with spacers as well?
 
Aug 3, 2020
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Sounds like a plan! I'd be going from 6 3/4" to 6 3/8". Looks like removing 3/8" leaves plenty of thread.
Thanks!
... of course I plan to measure a few more times before cutting.
Seems like this could be done with spacers as well?
Yeah, probably. I’ve seen people thread a couple crown nuts (or whatever they call them) on and use them as a guide. Also, you’ll ‘fix’ the threads when you screw the nut off.


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Starnger

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If you have no threading tool on your hand but a welder, i always just cut out the segment of the tube and weld it back together. It helps to put the short piece of a tube that fits inside the steerer to reinforce the connection and make sure it is straight.
 
May 5, 2016
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Yeah, probably. I’ve seen people thread a couple crown nuts (or whatever they call them) on and use them as a guide. Also, you’ll ‘fix’ the threads when you screw the nut off.
Yeah for sure, thread something (the bearing cone)past where you are going to cut, cut (with a grinder), and then back that thready thing off- should be good to go!
 
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If you have no threading tool on your hand but a welder, i always just cut out the segment of the tube and weld it back together. It helps to put the short piece of a tube that fits inside the steerer to reinforce the connection and make sure it is straight.
I’ve done this twice. The problem is the weld and reinforcing pipe have to be down far enough so that the stem can be fully inserted. Another issue is that the fork race can’t be removed unless you grind and file the bead down. The bead has to be low profile anyway to fit into the head tube. What I used to do in the 1970s if I needed to extend the threads on the fork tube was to take old top headset races from my junk, thread cutting oil and use a vice and breaker bar or pipe wrench to force the race beyond the existing threads. After some turns the thread grooves get less and less deep and it gets harder and harder to force it on. Just back off and throw it out and use another and another top race until you have the desired thread length. The races are harder than the fork tube steel so they press into the tube, but don’t actually cut threads. To install it into the frame a pipe wrench is required to tighten the race down. No lock ring is required and it won’t work loose. However, you have to use a pipe wrench to get it apart for cleaning or re packing. Works though. I used to do this a lot before I got one and one and a half inch fork thread cutters.
 

Starnger

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I’ve done this twice. The problem is the weld and reinforcing pipe have to be down far enough so that the stem can be fully inserted. Another issue is that the fork race can’t be removed unless you grind and file the bead down. The bead has to be low profile anyway to fit into the head tube. What I used to do in the 1970s if I needed to extend the threads on the fork tube was to take old top headset races from my junk, thread cutting oil and use a vice and breaker bar or pipe wrench to force the race beyond the existing threads. After some turns the thread grooves get less and less deep and it gets harder and harder to force it on. Just back off and throw it out and use another and another top race until you have the desired thread length. The races are harder than the fork tube steel so they press into the tube, but don’t actually cut threads. To install it into the frame a pipe wrench is required to tighten the race down. No lock ring is required and it won’t work loose. However, you have to use a pipe wrench to get it apart for cleaning or re packing. Works though. I used to do this a lot before I got one and one and a half inch fork thread cutters.
Yes, i do my cuts low enough to install the stem and clean the welds :) May still be not a good method for smaller head tubes like on bmx bikes.
 
Jul 25, 2016
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I finally bought a die to extend threads.

If your fork has threads far enough, use a hose clamp or 2 spare headset nuts locked together as a guide.

If the threads arent long enough, bike shop can thread deeper and probably do the cut for you.

I ve converted a fork from 1" threaded to 11/8 threadless, its hit and miss. But some of the thin wall 1 1/8 headtubes will slide over a 1" threaded. Rosette weld them on. Need to have a plan for fork race. I included a piece of the 1 1/8 fork to contain the race, also as a riser to put an old school fork on a mtn bk frame that had suspension.
 
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Jun 28, 2020
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I just used a chop saw to trim down my 26" springer steer tube, cut it like butter perfectly square. All I had to do was burnish the edges slightly at an angle with a file and that was very minimal. I should add the tube comes with extra thread, so I didnt have to mess with adding threads.
Before:
spring bracket 1.jpg

After:
assembled spring.jpg

This was the cut side of the section I removed. I'll never do this with a grinder again, even cut my sissy bar down this way.
cut stem leftover.jpg
 
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Sounds like a plan! I'd be going from 6 3/4" to 6 3/8". Looks like removing 3/8" leaves plenty of thread.
Thanks!
... of course I plan to measure a few more times before cutting.
Seems like this could be done with spacers as well?
If it's a half inch different, a spacer, or using extra threaded nuts could fill the gap and the forks could be used on the original bike again if needed. I've used extra washers and bearing caps to make up the difference so I wouldn't have to cut. The spacers are only on the top, never on the bottom of the tube. On the common springers they sell, they seldom fit just right, the bracket for the spring has to line up just right. Here I used a heavy piece of plastic tubing for the spacer. On top of the bearing nut there isn't nearly as much stress on the fork. Later I could use that springer on another frame if I wanted becasue it hadn't been cut down.

a3 - Copy.jpg
 
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