It is absolutely clear from the pictures that the entire bike is being tilted as pressure is being applied to the handle bars. Just look at the angle of the head tube as the bars are being twisted. That being said, if you think threadless stems are better, great! If you're a thread & quill person, amen! I have both. I ride both. I've installed and adjusted both. There are a few ridiculously and objectively wrong statements being made in this thread about both systems. Why do we find comfort in conversion of others?

Could you be more specific about what statements you find "ridiculous"? I have seen nothing that seems that out of true.

Here is a link to an article on threadless headsets from Sheldon Brown's web page by Jobst Brandt. I believe he is a mechanical engineer at Stanford.

https://www.sheldonbrown.com/brandt/t...s-headset.html

Even if they bike was absolutely straight in the photographs, if you can't see the bending in the bars....

You can loosen the whole assembly and turn it or, in the case of most threadless stems, you can remove the four bolts on the faceplate and take the bars off. Even if you do loosen the stem and top cap to turn the bars, the adjustment is trivial and can be done in seconds.

DannoXYZ,

You're just so hostile - or is it just Macho? Anyway, given your superior engineering knowledge, why don't you show us the calculations and specification of your 2" twist. Without that, all your engineering talk is just spew.

Nothing about the picture shows where the flex is occuring. Look closely at the top tube, its moved. That the ends of the bars are in different positions proves nothing. It is true that a larger diameter stem will be stiffer, all else being equal. Rarely is all else equal, but that ignores the question of how much stiffness is necessary.

You question the discussion of why? Why is what its all about. All the differences that you note for people to chose between, are all about why. Why should someone chose one over the other?

Lots of stem breakage at your shop, eh? Guess I'll avoid it. That's not common with well maintained bikes. Yes, some racers, on the edge, break parts of all kinds. They are generally exploring the engineering limits of the parts they use. Usually, its unncessary - like Hincapie's broken steerer. That is, a couple of extra ounces on a bike to make sure it doesn't break is not only good insurance, it won't hurt performance. No one that I have read has been able to extract, from real world performance, the benefits of having one of the lightest bikes in an given contest. Forget the theoretical calculations of energy to raise a gram a meter in elevation. Real world results don't mesh with the calculation.

One other point, the ease of changing bars is another red herring. To change bars, one has to remove the brake levers/shifters, bar tape/pads/grips, & accessories regardless of the stem type. If the need to thread the denuded bar through a clamping stem slows down the change operation by any significant amount, then the mechanic isn't very good. IMHO

So, we get back to nits. The issue isn't whether the stem is designed for a threadless or threaded stem, its whether the rider gets out and uses it. People blowing theories about whats best or right scare too many people away from good experiences on a bike. Which was my point all along.

Back in the old days of mountain biking, loose headsets were very common. Threaded headsets were just awful about loosening up. There were all kinds of stuff used to keep the headset tight - shaft collars, locking headsets, pinch bolts, etc. Cooltool (the first and best multitool ) even made wenches that would fit their tool so that you could adjust the headset in the field. I use to carry a set of small channel locks everywhere I went so that I could adjust either my own headset or someone elses on rides.

Threadless can, and does, loosen occasionally. Often I have a problems with them within a few hours ride time of installation but the adjustment is simply to loosen the stem bolts (typically 2 5mm allens), tweek the top cap to take out the play and tighten the stem bolts back up. It usually takes more time to get the allen wrench out then to do the adjustment. Complete installation of a fork takes just about as long.

The stiffness issue isn't just about marketing. Look at the physics and materials. A quill stem is a narrow tube that has to fit inside the steer tube of the fork. Being of a narrower diameter, it is made stiffer by using thicker walls but it still can't match the stiffness of the steer itself. A threadless stem is mounted outside the fork steer and is composed of tubing itself so it now has about the same wall thickness as the quill but it has a much larger diameter. That in itself makes the stem stiffer than any quill can be.

Because most threadless stems also use the same diameter tubing to connect the bars to the steer tube, they are stiffer in terms of twisting force also.

Threadless headsets may be cheaper to use during manufacturing but that doesn't mean that they are not a superior product. I have much experience with both and I can tell you that to make adjustments in the field is trivial with threadless. Making adjustments and installation at home is also trivial. Installation from bare fork to test ride typically take less than 30 minutes including cutting the steer tube. Installation from bare fork to test ride using threaded headsets typically take 2 to 3 times as long.

A couple of points:

First, looking at the picture, it looks like the quill stem is indeed twisting, at least a little. I can see the bike tilting a little bit, but the bars are tilting a lot more.

Second, your point regarding changing the bars is only partially true. To change all the components from one bar to another you are correct, threadless doesn't save much time. If you are changing the stem and not the bars, threadless is a HUGE time savings. To change the stem on a normal quill, you have to unwrap one side of the bars and remove one of the brake levers, so you can unthread it from the stem. To change the stem on a normal threadless stem you simply remove 5-7 bolts (usually all take a 5 mm allen wrench) and remove the bars and stem. Installation is equally difficult. Threadless does give you the option of 'flipping' the stem to allow some adjustment, and if you plan ahead, spacers give you a lot more room for adjustment.

God bless!
Wayne J.

Yes, that's about the only time it needs adjustment, after it's been apart, just like any adjustable bearing.

Oh, I'd agree it's quick, but how precise is it? With a traditional (threaded) headset you can adjust the stem up and down and side to side if the bars have turned and the steering head adjustment does not have to be disturbed.

How would that be? Not actually having had one apart, I'd assume you just push the stem clamp thingie down until it stops and tighten the allen screws, making sure the bars are straight. How precise is that? When I adjust my hubs after repacking, I turn the cone a fraction of a turn at a time to get the clearance exactly right. Same with the adjustable cup of my bottom bracket. It's a micrometer-like adjustment. A threadless headset seems agricultural in comparison.
Now, roller bearings are something that make sense. They started using them in some motorcycle steering heads 40 years ago.

Well, if you are like the moving company that I used from New Zealand to the US. You just put the front tire between your knees and snatch the handlebars to the side. This was on my MTB, so it was threadless. The front shocks broke before the handlebars moved. But, what the hell, I was 9000 miles away, so they just kept quiet and shipped it. There is no way a quill stem would hold like that.

Sorry, I only get defensive when I report the facts and other people operate out of rationalizations and jumping to conclusions. I'll see that a bear killed a squirrel and ate it and I'll report just "what happened" . Other people will try to say why that's "bad", "good", "silly" or that it didn't happen at all; we're talking about two different things completely. I say that bar-end flexes 2" and that's indisputable (see picture below), yet you not having experienced it doesn't make it either "good" or "bad" or "silly" or "untrue".

Debating "why" is like arguing why your preference of chocolate ice-cream is better than someone else's choice of rocky-road. Each person will have their own rational and subjective judgement, and they're all different. That's fine. Doesn't change the facts. Based upon each person's needs and requirements, they just select the attributes that work best for them. For some, styling and height-adjustibility is important, so quill-stems may best fit their needs. For others, stiffness and weight might be a factor and they can put up with some industrial-looking ugliness; that's fine too. Both choices are equally "good". There's no one "right" answer. Just because someone else chooses a different result than what you want (vanilla vs. strawberry ice-cream), doesn't make their choice any more or less superior or inferior to yours.

It's already been shown that Hindcapie's failure was due to the stem-cap being cinched up INSIDE the stem itself rather than resting on top. This yielded insufficient clamping on the steerer which required additional tension from the pinch-bolt. This squeezed the parallel sides of the stem into a trapezoid with the tight spot on the bottom pinching the steerer, resulting in a concentrated pressure point and notch-failure. It had nothing to do with the design of threadless itself.

And designs are always improving. New techniques are tested and tried in the field, racers being probalby the most punishing on their equipment. Our shop was the biggest in town and supported all the local clubs, so yes, we'll see a lot of equipment failures from racers. The large data group from our shop also points out the differences in the designs with not a single threadless stem failing. A major contrast to the quill-stem failure rates. Rationalize "why" as you will, the data and facts don't change.

Eventually we'll cease to see quill-stems being produced at all, except as vintage and collectors items. It's like debating drum vs. disc brakes, many people were resistant to the advance and progress of technology. Porsche and Ferrari were one of the last ones to adopt them with all sorts of rationalizations on "why" they're not desirable. But the facts and data on disc-brake's superiority is beyond judgement and eventually they too, must accept the new advanced designs. Look at Edison vs. Westinghouse...

Sorry, I should've said "changing stems", which is required much more often than changing bars. Reach and height measurements will change as a rider progresses. Higher fitness and flexibility after the first couple of years will usually require a longer and lower stem.

Yeah, I tried to keep the front-end as vertical as possible, but you can rotate the picture to make the headtube & steerer prefectly vertical if you want. The bar's angle relative to the steerer/headtube is still not 90-degrees, showing twist in the stem. Just measuring the distance between the left and right bar-ends to the fork-crown will take care of eliminating the small rocking of the entire bike or flexing of the wheels & fork:



The different distances only show movement between the bars and fork-crown. This is flex in the bars, stem and steerer-tube, anything further away is irrelevant in contributing to this distance. This difference in rigidity of the front-end doesn't make any difference in efficiency or speed, but it does give you better feel and control in sprints. I'm also a little leary of snapping stems and bars in sprints and the further you stay away from the material's yield and ultimate-strength limits, the better.

Well, normal threaded steerer is 1x24tpi thread giving you 0.00012" vertical movement per degree of rotation. Threads on star-nut/stem-caps are usually M6x1mm giving you 0.00011" vertical movement per degree, slightly finer. In either case, you can adjust bearing-clearance as precisely as needed.

The vertical bearing-clearance adjustment on the threadless is also independent of the rotation angle. You adjust the bearing clearance so it's smooth without binding using the stem-cap screw. Then you adjust the stem's rotation by spinning the stem around the steerer (or the other way around, doesn't matter). Then lock it all down by tightening the pinch-bolt on the stem. This locks in the bearing-clearance as well as the rotation adustment. You can also adjust the stem's rotation to center the bars later if you need to without disturbing the bearinng clearance as well.

Here's a site showing the adjustment procedures for both threaded and threadless headsets: ehow.com - How to Adjust a Bike's Headset.

Again, I'm not saying that one design is better or worse than the other, just that they have different characteristics and attributes. Depending upon your own personal desires, you can choose one or the other, doesn't matter to me. Notice that I use a quill stem on my bike...

The load on the bearing is set by the torque on the top cap. The top cap forces the stem and spacers down on a wedge around the steer (in most cases) so the load is adjustable in fractions of a screw turn at the top cap. Pretty fine adjustment and certainly finer than the old jam nut system of threaded headsets.

+1 for this. A skilled mechanic could jam the nuts just right on a threaded set to get perfect tension every time. Average joes often left too much slack or brindled the headset bearings. The top-cap torque system on threadless is easier to adjust accurately and more dummy-proof for the non-professional mechanic.

DannoXYZ

You can't win an argument if you don't understand what its about. Consider this clipped from my response: "So, we get back to nits. The issue isn't whether the stem is designed for a threadless or threaded stem, its whether the rider gets out and uses it. People blowing theories about whats best or right scare too many people away from good experiences on a bike. Which was my point all along."

Take a chill pill. Your arrogence is what hurts the sport. I suppose that you believe that its possible to build a frame that stiffer yet has a better ride too? That's marketing BS too.

You seem to think this is a battle of what's better, quill or ahead stems. I don't. If the bike works, ride it.

While its possible to make a stiffer stem by increasing its diameter, so what? Before explaining how important it is to transmit all your energy to the rear wheel, consider this. Generally, with aluminum, if it can flex appreciably, it will fail. Aluminum has low fatigue resistance. So, manufacturers engineer its application to minimize flex. Perhaps someone can flex it, but this is outside the normal range of use. Otherwise, they're facing warranty claims and lawsuits.

Dano, there are lots of opinions around the cracker barrel about why Hincapies steerer failed, contrary to your assertions. My point wasn't that a treadless stem was at fault. It was twofold (which you might have considered if not so emotional in your repsonse):1) racers live on the edge; 2) you can't win if your equipment fails. Taking that a step farther, if you're a racing, but aren't on the pro tour, you don't need to live on the edge. An extra few ounces won't hurt anything. So, as I said, weight and stiffness are red herrings.

One theory has it that in George's first crash he twisted his handlebars, that this put a score in aluminum steerer (bad materials choice for PR) creating a stress riser. He uses a King headset without a top split-ring washer. This allows a certain amount of motion, and in the context of the vibrations caused by the cobbles, lead to a fatigue failure at the stress riser. Pictures that I've seen of the failure tend to support this opinion.

But so what, you're still missing the point. Encourage people to ride, not to worry about what stem they're using.

I agree quill stems are on the way out. Not because they don't serve well, but because the audience for them has diminished to the point that they aren't generally profitable.

Cheers

That wasn't what I was addressing, so we're still talking about two different things. I suspect the OP had some real considerations and wanted some enlightenment on his issue.

Well, let's get back to the OP's question: "What is the advantage of a threadless headset vs a threaded?". That's all I listed in straight facts and that was my only intent with my original reply. Somewhere along the line, people debated why some attributes are better or worse than others, which is one step away from the actual facts themselves because it involves personal subjective judgement. For example, I doubt a stem ever thinks it is or isn't "silly".

You have some quick conclusions and assume it's hard concrete reality when it really isn't. I've talked with several manufacturers in the design stages of their stem development, I can assure you that there's at least 15 factors involved, many of them conflicting with each other. It's not as simple as narrowing it down to a single factor in why they go with a certain design.

No I don't, if you read my posts, I have never said anywhere where one's "better" than the other, just that they have different characteristics. I'm offended more by your assertion that my data of stems flexing is "silly" when you haven't done any testing yourself to confirm the actual imperical data. And after having worked in a shop for 10-years, I've come to realize that there's no such thing as all-or-nothing, black&white, yes/no qualitative solutions, it's all shades of grey. There's a wide range of attributes to all components and there's no one "right" answer for everyone. That's why I only listed characteristics of threaded vs. threadless and made no comment on why one should or shouldn't use one or the other; it's up to each person to decide for themselves based upon what they want out of their bike.

Really, some people want garage-queens that they never ride, that's fine. Some people want an 8lb bike to hang on their wall as art, that's OK too. I'm not going to make any assumptions on what the intended usage is and the OP never asked for recommendations.

To some people that's important. For control-purposes, especially when getting smashed on both sides in a sprint, I think it's important. For not snapping a stem in a sprint, that's important. The differences in failure rates are significant. If these events never occur in your riding, then it's no big deal to you. For others, height-adjustability and clean styling is important.

You can review all of my posts I've ever made here, I'll typically only talk about bikes and parts and methodology, and we can debate that endlessly which is kinda fun, but I make it a rule to never judge another person's post, or critique their writing or pass judgement on their character. But for you to judge other people's choices and consider their real-world experiences as "silly", that's beyond arrogant and is downright rude and insulting. It's fine to be a certain way but to say that others can't be the way they are, that's stepping over the line.

Danno...for what it's worth I agree that your posts have been objective, to the point and very informative. It seems to me that our friend has an issue with you personally which is a pity on such an interesting thread.
That photograph of the late and great Reg Harris taken from the front with the frame bending at a horrific angle would be appropriate here.

Danno...for what it's worth I agree that your posts have been objective, to the point and very informative. It seems to me that our friend has an issue with you personally which is a pity on such an interesting thread.
That photograph of the late and great Reg Harris taken from the front with the frame bending at a horrific angle would be appropriate here.

+1.

Moreoever, as I read through this thread, all of the doubting Danno's pictures is pathetic. So the bike is tilted each direction between the two pictures, but only very slightly. It's also obvious that the bars are twisted much more than the bike, in both pictures, and that this twisting occurs at the stem. As Danno addressed with arrows in the picture later.

These are the kinds of situations that make people who know what they're talking about less likely to contribute.

Both have their pluses and minuses, for my BMX I wouldn't dream of using threaded, aheadsets are stronger, easier to adjust as you don't have the lock ring working against the top cap. Provided that the tpi is the same on an aheadset preload bolt as it is on the fork threading they should offer the same level of adjustability.

A lightweight version of the motorcycle system would be the ideal imo.

My 2 cents: Thanks to DannoXYZ for clearing things up for those who were in the dark about this stuff. The flex photos are great. I knew threadles stems were flexy (only a fool will doubt that...), but this massive flex is new to me. Great info.

To me, the whole question is moot. Threadless is superior in every practical sense except for the ease of height adjustment. Lighter, simpler, stiffer, stronger, easier to set up and to take apart with no special tool, holds on to the steerer more firmly without getting stuck in it. Really, the threaded HS+stem is a pitifully weak engineering product compared to threadless. Just take setting bearing preload. TL: juggling with two nuts, trying to guess how much it will tighten up when you tighten the locknut, torquing down on it hard as you can... then loosen it again to correct the setting, a couple of times. Of course it's simpler if you have two wrenches, but who buys two? T'd: Tighten the clamp screws halfway, slowly tighten the top screw. When it's just right, tighten the clamp and you're done. The setting doesn't change, and it won't loosen up later, either. It's just more intuitive. You can do it on the roadside, with a multitool. If you don't have on on you, then the next biker who comes along will lend you one. Try asking for a headset wrench...

To me, the threadless system is more beautiful as well, but that's personal taste (Who likes the look of two 32mm nuts, though???)

As to those who can't see an inch of flex in two photos and keep arguing to try and save face... *shrug*

Hi LóFarkas!

+1 for thanking DannoXYZ on his excellent info.

I agree with you on your assessment of relative merits as well but your exception is a HUGE one! Height adjustment is a MAJOR factor in fit, and threadless (unfortunately) is woefully lacking. This sole shortcoming could be easily remedied if manufacturers would begin making stems (and ONLY for those who need them) that allowed both vertical and reach adjustments (beyond the "swinging neck" design offered by all adjustable stem makers). Such stems would, undoubtedly, be less rigid than "standard" threadless stems, but for those who really need height adjustments, they'd be a Godsend.

I don't diss riders who use older quill stems despite the flex. Some riders just like the looks and some need that height adjustment!

I will agree that many current bikes with threadless headsets have very little room for vertical adjustment of the bars. Blame the bike manufactureres. Manufacturers could just leave the steerer tube a bit long and put in some spacers to make this whole thing a non-issue. You can flip a stem back and forth and move spacers up and down in the stack.

Specialized makes a stem with an eccentric shim inside that can be set to +16, +8, -8, and -16 degrees. Couple that with a stack of spacers 20mm high or so and you have a stem that can be adjusted vertically by 2 inches (assuming a 110mm stem). If you leave more spacers in the stack originally, that range can be even greater.

In short, the problem isn't that threadless can't be adjusted vertically. The problem is manufacturers who don't leave any room for vertical adjustment. I think it is comparable to using a quill stem where the minimum insertion point is set so high that it only allows 15mm of vertical adjustment.

God bless!
Wayne J.