When I left the cycling world back in the early 80s we pretty much had threaded head sets and quill stems. Now that I have returned, and am trying to catch on the years that I missed and the new trends and such.... I find that I am curious about threadless headsets. What exactly, for the everyday cyclist, is the advantage of threadless over threaded? Or is their one? Admittedly, they do look pretty cool in some respects. But is one better than the other?

Threadless:
+ Lighter weight
+ Stiffer
- Difficult to achieve good aesthetics on bikes with skinny tubing

Threaded:
+ Vertical adjustment is silly easy
- Easier to damage your steerer (i.e. if you overtighten the quill's expander)
- Most quill stems don't have removable faceplates, so changing stems i.e. for reach adjustment tends to be a lot of work

More pros for threadless:

+ no more stuck stems
+ easier to swap stems without having to unwrap bars and undo brake levers

Really, even though all of my bikes have threaded steerers, I think threadless is the way to go for new projects.

they also make nifty cap options for threadless stems

Threaded headsets served very well on road and street bikes for just about a century. But they ran into their design limitations with mtb, where headsets coming loose was a common problem.

Threadless headsets aren't better on that score, but they are more easily re-adjusted, needing only a 5mm hex key. The design alos paved the way for lighter and eventually aluminum and CF steerer tubes, so even at the same weight for the headset, the design made lighter bikes possible.

I rend to be retro and still prefer threaded headsets for trouble free road bikes, but use threadless for everything else.

In any case, unless you already own some high end retro parts, you don't have a choice, since all modern stuff is threadless except for the low end.

I have a threaded frame in the queue, unless I change my mind. Threadless has a lot of small advantages. The one disadvantage is vertical adjustment. For fear of jinxing myself, I've never had a quill stem get stuck, but I have seen it happen. But it takes a lot more care to prepare a threaded fork in the first place. I've recently seen someone searching for a headset with less stack height because all of the easily available ones didn't fit his threaded steerer.

Vertical adj. for threadless? Just don't cut the steerer tube?

It's easy to overstate the vertical adjustment benefit provided with threaded headsets. Most stems only allow about an inch or so of adjustment.

Works fine as long as (1) you get it right the first time, and (2) you don't need the height to change. If you keep the same bike for 15 years and get to the point that you need the bars 3/4" higher in March than in September, threadless "adjustability" sucks.

From an aesthetics perspective, IMO the threaded have threadless beat hands down. But as has been said, it is so much easier to swap bars on a threadless set, but harder to change the height.

Another benefit of threaded headsets is that thet stay adjusted when the bars are removed for travel, though threadless is better if you also need to drop the fork.

Other than aesthetics, my preference for threaded on road bikes, is that they allow me to tighten the stem race tight so the bars will twist in a crash, possibly saving the fork or front whee. Threadless stems set race tight tend to cause loose headset, though there is a workaround if you fit a clamp collar to preserve headset adjustment when the stem isn't tight enough to do the job.

Pretty much every bike out there has at least an inch of spacers. My race ready roadie has 3cm. Usually it's a good idea to leave a bit more than 3cm even if the steerer looks silly with the stem slammed. You also get an inch difference by flipping a 7 degree 120mm stem. That's 2 inches with even the more racy models. And that's not even considering larger angle stems such as 17 degree.

The minus in this is that you need to have a selection of stems for maximum adjustability. Then again it's never a bad idea to have a few extra. And having different lengths means you can keep the reach constant with height adjustments. With a quill this is more difficult if they arent faceplate removable.
Not to mention quills usually cost more

There have been threaded 1" longest , threaded 1.125" common less , but still used .
I have 2 'folding' bikes with threaded 9/8" steerers..

In 1" the tube was thicker at the Bottom, as stiffness increases with diameter
the steerer became a straight tube.. which lowers MFG cost a bit.

now threadless is most new bike production..




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Aside from aesthetics, the main knock on threadless stems is height adjustability.

Aesthetics? I think quills look better on a bike with classic steel or titanium tubes. I think threadless look better on more modern, larger aluminum or carbon fiber tubes.

For height, it really is a non-issue. You can get as much height adjustment pretty darn easily with a threadless stem -let's say, 1-2 inches - which is all one would generally be looking for with a quill stem anyway.

Don't cut the steer tube, leave it at the maximum length allowed by the manufacturer (usually ~70-80 mm from top of bearing to top of stem = 30-40 mm spacers + 30-40mm stem). Use stem angle and spacer placement to get the bars where you want them.

Higher bars: put all the spacers below the stem (if not there already) and/or flip the stem to angle the stem upwards and/or swap to a more upward angled stem to get the bars up.

Lower bars: flip the stem downwards, or change to a less angled stem flipped up or down ... and/or put a spacer or two above the stem - limited to compression plug guidelines. Heck, get a different compression plug that requires spacers above the stem if needed - they're cheap and easy too.

Difference between a steep angled stem downwards vs. upwards - probably more than an inch. You also have two intermediate steps if you're willing to invest $35 in a second stem.

Add another 1/2 inch for a 10mm stem above vs. below the stem.

So there's no reason you couldn't have good incremental adjustability - easily equaling a quill stem - without a lot of hassle.

My guess is that those of us who bike enough, and know enough about fit to be concerned with this are maybe the type who use maximum spacers, and they're all normally below the stem anyway. So the height adjustment would be a simple flip of the stem or a quick swap to the "spring" or "summer" stem.

Is this as easy as just raising or lowering a quill stem? Maybe not, unless your quill stem is seized, but certainly not more than 10 minutes of easy DIY effort with normal tools, a couple of times a year. And you won't end up scratching your beautiful, possibly vintage, cold forged quill stem. I won't even get into situations where you want to change bars.

The only limitation might be one's sense of aesthetics. For some reason, among the aesthetics police of road bikes, spacers are a no-no, as are steeply angled stems. That's just dumb. The threadless system is designed specifically for that sort of adjustability.

Yup, spacers above the stem work well, if the bars feel too High,

as you get older you may want the bars higher, then, you can always shuffle the top spacers back under the stem.

But, the cut steerer tube won't grow back.






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If you're actually changing handlebars, single-bolt isn't really any worse than removable faceplates, since you'll be removing everything anyway. Changing the stem is where removable faceplate shines.

Hey, thanks for all the comments! It's an interesting subject. I currently have a quill step with a removable face plate and adjustable angle. Works well enough for now. I put some anti-seize on it, so I don't think I'll have a problem with it get stuck any time too soon. Still, sometime down the road I may convert my bike to threadless, if for no other reason than the experience of doing so. But that's way down the road for now.

This is the main benefit for me.


-Tim-

Umm, don't cut the stem, ever. At 6'4", I usually need all the steerer tube I can get on an xl frame. Just put the stem spacers above or below the stem as needed. Clear? One could also use a stem or bar with more rise. Theadless have been on mt bikes for along time now, no issues for me.

I built my One Off, last tour frame, with an extended threaded steerer tube ,
all the extra thread became its own headset press.

And, to be fair, there's no reason why a quill stem couldn't have a removable faceplate as well. Or why you couldn't use a threadless adapter to mount a modern stem on a threaded fork.