I just bought a "modern" bike with a threadless steerer tube, headset and stem... and I'd like to convert to a conventional (old school) threaded set up. Is it safely possible to thread the steerer tube and make the conversion?

no

+1

Can't be done safely. Don't even try.
Replace the fork with an already threaded one if it's that important to you.

toecho the other thoughts, don't do it.

OK, thanks.

If you don't mind, why? What are you hoping to gain? I'm not trying to start a debate; I'm curious.

Threadless headsets are highly overrated. You just can't get the stem as high as you can on a quill.

Plus the fact that threadless headsets and stems just look ugly.

I really prefer the threaded headsets and the option to adjust the height of your handlebars. I don't know what the advantage of threadless could be.

Stronger, lighter, allows for the use of fork steerer materials other than steel, and easier to service. The only non-aesthetic drawback is a lack of quick and easy bar height adjustment - which isn't really much of an issue for the vast majority.

if you really want to go threaded, it should be pretty easy to find a threaded steel fork somewhere and have it painted.

https://www.rivbike.com/products/show...ms-fork/50-718

Certainly, you can thread the steerer if if it meets certain conditions, and you have the tools and skill.

The first is that it needs to be made of steel, and not be too hard for threading. You can test for this with a file. The second requirement is that it must have a 1/16" wall thickness, as in 1" OD, with 7/8".

Assuming the conditions are met, I suggest letting a skilled shop do the job, since the cost of decent tools for this is significant.

If you decide to have it threaded and the LBS refuses or wants too much, PM me & I'll give you a referral.

sure you can... just don't cut the steerer tube too short.

Utter load of horse crap. I know he's trying to market his product, but dude should be more honest and less hysterical in his salesmanship.

These days there are a bigger variety of threadless stems to put your bars where you want them to be than there are quill. Or can you show me a 1" quill stem with 130mm extension, 26.0 barclamp and +15 angle? Easy enough to find in threadless, but I've been looking for a quill with those specs for months. (yes, I could use a Technomic and extend the quill another 60mm but I hate them; soooo flexy, and the 130mm seems to be gone.)

However, it should be a crime for a bike shop to sell bikes off the floor with a cut steertube and no spacers above where they put the stem.

Threadless setups are lighter and stronger, therefore look infinitely better to me.

Some even have tidy clamp bolts.

The OP asked a simple technical question which was whether he could thread a fork, if he wanted to (as he apparently does). Unfortunately it's become a debate about the superiority of one headset design vs. another, which is beside the point.

I have bikes with headsets of both designs, and functionally it's impossible to discern a qualitative difference. The ease of adjustment of the threadless system is nice, except that I've never had to readjust a threaded headset once setup in 40 years of riding. For my road bike I like the ease of adjusting the height of a quill stem, but there again once I've dialed in my position that doesn't ever change. I also used to prefer the classic look of the quill stem road machine but I've gotten used to the look of modern bikes and they don't look wrong any more.

In short, I can't think of any strong reason to discourage anyone from setting up his own bike the way he wants, so it's back to the simple technical issue and personal preference. If the OP wants to change his headset system, he shouldn't have to justify his reasons for doing so.

I thought that with a few exceptions (Surly, Salsa?) most bikes come to the LBS with the steerer already cut. I agree it's a crime and makes fitting a bike VERY hard for me, but the crime was commited at the factory, I believe. I'd LOVE to hear I'm wrong, though!