Doc_Wui

I bought a 1" threaded fork to upgrade to disk brake mounts and suspension for my old Trek 800 Antelope. The steerer tube needs another two inches of threads cut before it will fit. OK, I can do that, maybe.

So I got a 24 tpi 1" die and spun it on the end of the tube. It's very tight on the threads, so I realize this could be a long struggle with a lot of curse words that might not end well.

Then I thought, can I convert this to a threadless headset? They sell 1" threadless units. I hope the bearings will fit in the existing races on my Trek, or I guess I can replace the cups? And I know I need some added pieces for spacers nad to mount the handlebars.

It's not a matter of cost. I'd pay an LBS to cut the thread but the first two shops wouldn't do it.

fietsbob

the other part you may not have is a bicycle specific tool handle .. [another approach is a Machine shop the die is turning in the head]

there is an abundant flow of cutting oil ideally you take an 1/8th~1/4 turn, cutting, back off and clear the chips,

then take another partial rotation cut..

there needs to be No Chrome plating..


realistically (not able to supervise the job in person) do the threadless conversion ..

you can mix it up, threadless upper headset race + spacers

and a locknut and the top nut jammed against each other.. to not come loose..


I have a fork that the Frame Builder & I did cut more threads .. in retrospect the threadless-threaded mix would be stronger.

FWIW, the outer frame insert cups in a CK threadless and 2 nut are the same ..

It's the center part pressing on the sealed bearing inner race that differs.

CrippledKonaBoy

Keep it simple -- the same threadless spacers will work under the top nut of a threaded steerer. Been there, done that.

Doc_Wui

It's not chrome as I know it, but the upper part of the tube did look shiny/polished. I thought of putting a torch on it til it got red and letting it cool to kill the hardness.

Doc_Wui

I got it now. I'll get a 20mm and a 5mm spacer if needed, a 1.125"-1.00" shim, and a 1 1/8" stem with an adjustable arm. Use the threaded nut/lock washer on top.

It will look kind if chunky. but that's OK.

I did run the die down to try cutting. That surface is way too hard. I tried a torch to see if I could burn off any coating. Nope.

wschruba

Like @fietsbob said, you need a die handle. It's not clear that you have one. You could theoretically thread it without one, but it's incredibly difficult. It's rough going, even with a foot-long handle and the proper tool (the bicycle die is split and requires a set-screw to make sure it is perfectly sized for the steer tube).

How much of the threaded portion is sticking out? Is there any reason you can't just put a whole bunch of spacers on the steer tube (ie, it will be too high for your stem)?

frankenmike 

I would get a 1" threadless headset and threadless stem, were it me.

skye

Ugh, been there, tried to do that. I'll join the crowd and say go threadless.

Doc_Wui

LOL. Would have been better off buying a welder and learning how to make it sing, or talk, go bzzzt, or whatever a clean weld sounds like. Then I could put tabs on that existing fork.
.
Well, I will have parts for several option available to me. Use a threaded headset with spacers, and the old quill. Use a threaded headset with spacers and a new stem. Use a threadless headset with spacers and a new stem.

I've seen the bike dies in use on youtube. Not at all like my cheap one.

FBinNY 

You need an unthreaded length roughly 2" more than the threaded fork you're replacing. That allows that all the thread will be cut off. If it meets that test, keep it simple and go threadless. If it's border line, there's a bit of fudge room as long as most of the fork inside the stem is unthreaded.

For example, if you set it up with all unthreaded in the stem except for the top 1/8" plus a bit extending into a spacer above the stem, that would be OK, since there's no effect on the structure.

OTOH if the thread area extends through the stem, and there's threads cut between the stem and headset, you have an almost 100% assurance of premature and catastrophic failure at that threaded area.

Doc_Wui

Well it's 9 months later. Last week, I said "time to do it," and I mounted the threaded steerer tube with a threadless headset. I do want to thank the people that told me to go threadless. I was able to cut it well short of the threaded section, so no strength issues. I'm using a 1 1/8" stem with a shim. Fits tight.