It's more a personal choice

I prefer threatless

I like threadless. The rest of you suck!

which pretty much coincides with the time that carbon forks became the norm. Threadless lets you build a much lighter front end. Moving to carbon forks pushed it over the edge because now you could have Al and SF steerer tubes which make things even lighter.

I've built and ridden all threaded bikes so far, but can definetely see how threadless has an upper hand on threaded on everything but aesthetics; I'm making my new IRO threadless since it'll be a beater...should be a fun experiment.

You can always get the 1" IRO and get a threadless 1" headset.

Who wants to have to rewrap their bars if they want a new stem? The only reason to bother with quill stems is if you have an older bike. Outfitting a new bike with a quill stem is idiotic. Take that, Grant Peterson.

Finding 1" threadless forks is kind of a pain

Thats why you just use 1 1/8" with a shim.

You can't negative shim.

The selection of 1" threadless forks is more limited. They are nice for upgrading older bikes that take 1" forks, but if you are buying a frame new make sure you get 11/8".

oh forks. yeah it's possible but there aren't as many choices and definitely not as many deals.

I also enjoy lack of threat.

i say threaded looks the best when coupled with matching track drops, and or is a drop stem.

but threadless by far is the most practical and stiffest/strongest/cheapest/bestest option out there.

i wanted to go threaded, because i have so many quill stems with bars in them laying around, but im going to bite the bullet and embrace progress. i cant wait to be able to switch bars without rewrapping or messing with grips.

one of us one of us one of us

I tried the torsion test on my 10cm quilled bars today and damn, they are really quite flexy. Dutret, when all of the bunk is debunked, what will you do then?

Quantum singularity.

How would a steel quill stem compare in flexiness to alloy quills or alloy threadless stems? It seems that a steel threadless would be stiffer than a steel threaded.
I ordered an iro with threads and have been thinking about changing it, but then I wouldn't be able to run a really awesome front rack I found.

I'm going threadless, clipless, brakes. There, I said it.

1 1/8" threadless headsets have taken over the market, evil little things, and are coming to attack your lugged track bikes!!!

I'm pretty sure that even the bestest keirinest steel quill stems (edit: talking about traditional 1" skinny ones here) are flexier than the crappiest threadless stems. You can't **** physics. I don't think there is a steel threadless stem, at least not widely used. There's no need for one.

Steel isn't all that stiff: https://www.pbs.org/wgbh/nova/bridge/images/tacoma3.avi

That's from wind.

not opening on my work comp but i'm pretty sure i know this vid.

that's actually from sympathetic vibration induced by wind, iirc. every object has a frequency that, if it vibrates at that frequency, the vibration waves magnify - instead of ever canceling each other out, they build and build and build until, well, you have a seriously ****in' broken bridge. [can somebody check my physics explanation? i'm just tryin to remember from high school physics here] edit:: vocab word: RESONANT FREQUENCY.

that doesn't mean that steel isn't stiff or strong or any other adjective or characteristic.

cool video though.

I love that video. Quite possibly the coolest thing that has ever happened in the history of the world.

salsa still makes steel stems......i think they even do a custom option,i know they used to threaded/threadless....any lenght/rise you want

Don't worry, I took enough physics & engineering classes to know the real cause was resonance. Just wanted to point out that even "stiff" metals like steel can flex surprising amounts.

Edit: Here's the wiki on resonance for anyone curious https://en.wikipedia.org/wiki/Mechanical_resonance

Forget steel, we all know it can bend like crazy. What really amazes me is how the actual ****ing concrete waved all over the place on the Tacoma bridge without cracking. Yeah, that's a classic vid.
Incidentally, the bridge offered a wide (tall) target and a not very aero shape for the wind to attack and it was ridiculously narrow for its length AFAIK. So it was poor design + really bad luck.