Quill stem design question
 

Hi folks, I've tried searching this but haven't had luck specifically on the advantages of these two clamp designs. Is one superior to the other in terms of durability? I'm looking to get a shorter reach stem, and while I don't ride aggressively I just thought I'd learn something here. Thanks!

http://i.imgur.com/mbbaYEf.jpg

Good question, never thought about the superiority of one over the other. As far as I can tell it's just style, although some of our more experienced members might charge in with better knowledge.

To my eye between the two pictured the difference is a mix of aesthetics, a sliver of weight, and stiffness and connection strength. Note that the stem on the left has the bar clamp bolt rooted into the body of the stem while the stem on the right has an extra ear that the bar clamp bolt travels through. Extra material = extra weight all else being equal (granted that's not enough weight to matter to most of us except for want of 'correctness'). The stem on the left also looks to offer a slightly more positive connection between stem and bars as there appears to be more contact area between the two - less of a gap in the clamping area. The gap of the stem on the right is also in roughly the same plane as forces exerted on the bars during a strong out-of-the-saddle effort (pushing/pulling on the bars or hoods while sprinting, climbing), and may be less resistant to flexing than the stem on the left which appears to offer more 'vertical support' at the stem/bar interface.

These are all decimal points which may or may not matter depending on the application. Both designs should be fine without need to worry about strength/failure. If I were deciding between the two pictured and wasn't concerned with which would be correct for the bike, I'd choose the stem on the left.

Correct me if I'm wrong, but it appears that the "conventional" stem on the right has a sizable cutout in the front above where the bolt threads in. If so, that much material removed from the clamp area would probably weaken it more than I'd like, and I seldom yank on the bars. If this photo effect is just a trick of the light, then disregard.

^Very good point.

Can't disagree with the assessments but can add additional perspective. The total length for circumferential deformation is greater for the stem on the left. The cross section of material is greater as well, taking into account the point from [MENTION=399166]thumpism[/MENTION] observation.

In terms of "better," I would need to know the mechanical properties of materials between the two. If they were the same, I would lean to the one on the left. Why? Because if you really tighten the clamp on the right one, I would be concerned about the stress concentration leading to failure, taking the cutout into consideration.

The one on the left is a little more "aero", and I find it a little more aesthetically pleasing as it hides the bolt.

Some stems, e.g. the Sakae Ringyo "Royal" were milled at the factory in this manner. I've been using one for years with no problems.

http://www.os2.dhs.org/~john/fixed-frame/bars.jpg

Rethinking this. The gap being perpendicular to the plane of pushing/pulling on the bars (left stem) may actually be a little less stiff...it does keep stress risers (edges of the gap in the stem) away from the maximum stresses/deformations in the bar, which is nice (roughly a few degrees off the top/bottom of bar). If not riding aggressively as you state this is all a moot point anyways.

Again, decimal points that likely don't matter in most real world conditions.

Without disagreeing with any of the above, I see mainly a chronological difference. The stem on the right is an earlier design.

Note also the stem on the right has a steel bolt with a steel nut, while the other has a steel bolt that threads into a threads tapped into a blind hole in the stem. That hole is a potential weak spot. It is alsopossible to strip the threads.

I've had a couple of these, as well. Never an issue.

The stem on the left requires a blind threaded insert for the clamp while the right stem needs just a press-in insert.

Wow! Thank you all for your insight. I did not expect to receive so many comments.

My current stem is the style on the left, but I am very curious to try the right side. I want to get first hand experience to compare. I'll provide some feedback once I can get my hands on one!

Given the amount of material, I would be surprised if the stem on the left had a threaded insert. The threads could run deep. More thread engagement than the one on the right. If the one on the left had 3x the thread engagement, it would be a wash in terms of stripping force required, if the thread pitch were the same. Oh I said thread engagement! Doh!

I'd think you'd have to go well over a reasonable tightening torque to strip those threads.

I much prefer the clean look of the left stem with he bolt screwing into the stem proper. But I've never seen anything like the stem with the milled opening in front. I'd probably chose it just because it's interesting. Maybe try putting a piece of matching handlebar tape behind the slit. Might look good or like crap, but I'd try it.

Or one can put a nice picture of their girlfriend, wife or even mom in that slot so thy are always with you when you ride....:rolleyes::D
Dang!, it must be getting to be "Miller Time" now. I'm starting to think kinda weird already.....

some designs like that on the left removed too much material and were prone to failure. Not the pictured design but the modolo stem with the hole all the way through and a steel nut inserted from the top is one of note.

Its pretty easy to strip alloy threading, especially considering the bolts are usually steel. I've done it. Which is absurd considering I have a dial-type torque wrench and should have been using it.

In fact at Veloswap if you could sell all the stripped out alloy stems for five bucks you could easily buy a nice Columubus SL bike. I don't know what the sellers think, they always expect someone to use a helicoil or something, or they think they can be retapped with a bigger bolt maybe? Very easy to ruin alloy threads.

I don't like the bolt on the bottom of horizontal, or negative drop stems. It makes me think of a really old bike from the 60s/70s, and looks clunky like a Schwinn component. Then again I think negative drop stems and that aesthetic is a design flaw in the first place. The negative drop stem uses more material and weighs more than a stem that just moves up from the quill column to the bar clamp, its much more flexy, and it creates a dangerous place where you can hit your knees or bits in an accident. However, the horizontal or -17 degree drop stem is considered classic looking aesthetically. There is a reason that geometry and inefficient approach to stems went out when mountain bikes hit the scene and on road bikes with the Aheadset. Quill headsets, and quill stems really were just boat anchors and a bad design.

I think every bike I own other than the 29er uses Quill stems. My favorites are the Cinelli Grammo, Control Tech, Ringle, and the Answer ATAC. I have Nitto stems, but they are too flexy now that I've switched to mustache bars. A 56cm bar really puts some leverage on and stresses out a quill stem. I remember having a Nitto Technomic on our first tandem. I thought I was going to break it just holding on to the bars. I couldn't get that thing off the bike fast enough. We put a Salsa rise stem on that moved at an upward angle to the bars instead of the negative drop style. Totally different in terms of the stiffness and the confidence you get on the bars. With modern bikes on Aheadset style steerers and stems that kind of flexyness is a thing of the past, so some won't even understand.

I was always fascinated with the hidden bolt stems that came out. I think Cinelli made some, and one was even an Ultegra stem, if I remember.

I'm also sad I'll never get to use my Cinelli Grammo. Since switching to mustache bars on every bike it doesn't give me proper fit, and I'll never get to use it. I might have to actually leave one of the bikes with road bars just to get on it, or trade it for something I really want.

I think the one on the left has a clamp design that would be better for very short extensions, since there is only one interface to the bolt, and it is vertical.

At the end of the day, as it is here, the designs and materials that we try to evaluate are only vaguely suggestive of a frame or component's reliability and flexural performance.

It really does come down to product testing under varied conditions and extended intervals, as well as the quality control inspection/testing that follows.
It is in the end a matter of the manufacturer's reputation that counts, above all else, though I myself remember flex-testing a PX10's handlebar and rejecting it's stem's worthiness from the get-go.

for the funky and confused retro type

[IMG]https://farm2.staticflickr.com/1635/...11de7c82_b.jpgPhoto0501 by carrera247, on Flickr[/IMG]

[MENTION=350383]crank_addict[/MENTION] - Is that adjustable?

If like the Cinelli 1A on the right (often copied), the piece on the front is a chrome plated Steel Nut, in effect.

Nitto is still making one in that type , but 'Nut' is towards the back.
ttt uses a front bolt & steel insert They started at a 6cm extension.
I have been using a 1A 8cm.

the one on the left the bolt screws into where the Aluminum is threaded for the purpose..