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PostPosted: Mon Oct 07, 2013 7:38 am 
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Stephen, isn't stiffness to weight ratio in a crank a bit of a really silly number. Sure its valid when comparing one generation of cranks to the next (i.e we made the crank lighter and stiffer, or we made the crank a lot lighter but lost very little stiffness.), but comparing one superlight crank to another mid-weight one, stiffness to weight ratio seems to me like a wierd term, when the mid-weight one is actually much stiffer in terms of absolute stiffness. And that's the difference the user can tell.

Granted, a stiffer crank may not improve actual performance or drive train efficiency, but it does alter the feeling of being 'connected'.

Sorry for a lot of OT, but on that note, the OP talks of stiffness in this stem and I really wonder, stiff compared to what? Next to the actually stiff stems (Zipp SL145, PRO Cavendish Carbon, etc, the 'sprinter' stems), isn't this ~80g/130mm stem just a noodle? You've convinced me that it may be stiffer than Extralite, Syntace, etc. But that's stiffness to weight ratio comparisons, right? What about actual (absolute) stiffness if that is ones priority?

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Last edited by DMF on Mon Oct 07, 2013 8:27 am, edited 1 time in total.

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Posted: Mon Oct 07, 2013 7:38 am 


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PostPosted: Mon Oct 07, 2013 8:06 am 
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Good luck with your products. As a 6'5"/85kg rider I feel the Calnago feeling about super light parts, in particular stems. The lightest stem I used is the new Superlegerra, claimed at 100g, weighted at 120g for a 120mm...


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PostPosted: Mon Oct 07, 2013 8:17 am 
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^ me, too, but I've been told before I don't belong here. :-)
I also replace ti bolts with steel ones.
The stem on one of my race bikes is at old-ish Tuned, which is easily over 200g (110mm)! Oh no! :-)
For all I know, it could be a MTB stem, but it's oversized, so I dunno


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PostPosted: Mon Oct 07, 2013 9:08 am 
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DMF wrote:
stiff compared to what? Next to the actually stiff stems (Zipp SL145, PRO Cavendish Carbon, etc, the 'sprinter' stems), isn't this ~80g/130mm stem just a noodle?

To me, statements like these just miss the mark.

Just because something looks/is heavy, it isn't automatically stiff or strong. Without comparable testing these claims are almost pointless - feel is simply not a good enough gauge for the most part.


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PostPosted: Mon Oct 07, 2013 10:00 am 
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jooo, you should really try something like a Zipp SL145, by feel alone - the stiffness compared to say a Thomson is just mind blowing. The difference is not something minuscule that you just barely sense, it's a whole different bike alltogether.

I'm not saying heavier is better, but it's hard to believe claims of something that is just extremely light also being super stiff. Sure in a stiffness to weight ratio comparison, but as I said. That really doesn't say much about actual stiffness... Something 1/4 of the weight at twice the stiffness (to weight) is still only half as stiff.

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PostPosted: Mon Oct 07, 2013 12:20 pm 
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DMF wrote:
Stephen, isn't stiffness to weight ratio in a crank a bit of a really silly number. Sure its valid when comparing one generation of cranks to the next (i.e we made the crank lighter and stiffer, or we made the crank a lot lighter but lost very little stiffness.), but comparing one superlight crank to another mid-weight one, stiffness to weight ratio seems to me like a wierd term, when the mid-weight one is actually much stiffer in terms of absolute stiffness. And that's the difference the user can tell.


I take your point and when you want the stiffest crank possible then yes, it is a bit of a silly number as the heaviest cranks will undoubtedly have the potential to be the stiffest. However, this is weight weenies and everyone is aiming for the lightest components possible whilst still trying to keep the functionality. Inevitably, the lighter a component gets, then compromises will be made. In terms of absolute stiffness, I would imagine that Dura Ace 9000 is the benchmark, but that's not a typical weight weenies crankset (although I have been told by a time triallist that Tiagra cranksets are stiffer still but also far heavier). If you want light weight, then you want to know what compromise will have to be made in achieving that light weight. So comparing stiffness vs weight can be a a guideline for what you are getting from your crankset. I would also compare absolute stiffness as well if you have concerns about the overall stiffness of the crankset.


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PostPosted: Mon Oct 07, 2013 12:43 pm 
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Stephen, I agree completely with everything you just said. So in one meaning of the word DA/RED might be considered benchmarks for stiffness.

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PostPosted: Mon Oct 07, 2013 1:28 pm 
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If you're considering stiffness exclusively, then yes, absolutely.


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PostPosted: Mon Oct 07, 2013 4:09 pm 
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stephen@fibre-lyte wrote:
I always imagine the benchmark to be the one that all others aspire to be like?
My definition of a benchmark is simply something against which others are evaluated. It doesn't need to subject to bias. And the resources for the crankset development were neither my own nor from an investor. I'm just a poor guy who loves riding and found myself in a unique position to design some cool stuff. Let's not go off topic and stick to stems and stiffness.

DMF wrote:
What about actual (absolute) stiffness if that is ones priority?
Good point. Being so light, this stem probably won't have stiffness levels such as those purposely built for it, nor was it intended to. Thankfully, my stem design isn't a wet noodle, as light as it is. If it was, I'd be ashamed to showcase it.

It's hard to quantify what constitutes ‘feeling stiff’ though. To some, a certain stem is stiff enough, and to others it's not, depending entirely on the perception of the individual. My benchmarks were Thomson for stiffness, Syntace for durability and Extralite for weight. All make excellent products. Though "feel" may be a good indicator to some, sensitivity differs from person to person and can be unreliable.

For example, although I calculated the absolute values of my own stem design under certain load cases, and only know the approximate stiffness of certain stems compared to another. Fortunately, I've ridden/worked with various stem brands/models with the same bars and in similar lengths. From Pro to Ritchey, 3T, Syntace, Deda, Ringlé, Specialized, USE, Zipp to no-name el-cheapo, also in various materials.

My ideal method of comparison would be a standardized test to measure deflection, isolating a stem from fork and handlebar. Hopefully, it won't be long before I'm able to generate some numbers, though in my view such a test is best done by a 3rd party to prevent favoritism. I'm seeking a party with whom to do this without getting charged excessively.

DMF wrote:
The difference is not something minuscule that you just barely sense, it's a whole different bike alltogether.

I'm not saying heavier is better, but it's hard to believe claims of something that is just extremely light also being super stiff. Sure in a stiffness to weight ratio comparison, but as I said. That really doesn't say much about actual stiffness... Something 1/4 of the weight at twice the stiffness (to weight) is still only half as stiff.
Indeed, notwithstanding the hypothetical nature of this argumentation.

I find STW values somewhat misleading, since a difference in mass isn't something particularly noticeable. I prefer to avoid relative terms like strength of stiffness-to-weight, however exciting they may sound to some. Most ‘scale-weenies’ don't realize that strength doesn't necessarily correlate to either weight or stiffness and STW is merely the outcome of a division of mass by a given force or deflection coefficient. It needlessly complicates.

Conclusion: how stiff a design ends up at is all in the combination of a given material, processing and fabrication, design (engineering) and finish. That's what makes industrial design and mechanical engineering so exciting, and there are so many variables that, as you indicated, no two bikes will feel the same, even when they look identical.

User Name wrote:
but I've been told before I don't belong here.
I also replace ti bolts with steel ones.
You're welcome here. I don't see why you wouldn't belong in this discussion. I found many titanium bolts to be inadequate for stems. I've had some stems that had 'em and experienced no issues with them, but I've become more careful when it comes to putting a product onto the market. I wanna rule everything out that can go wrong as much as possible. For production stems, I contemplated going with steel, since I've had some issues with prototype bolts. These weren't due to a faulty design, might I add, but rather the handiwork of poor craftsmanship from machinists.

I found a solution in a novel process that forms/forges the Wert 6Al/4V titanium bolts in a single operation, thread, head and everything. These bolts have been tested significantly stronger than steel or other titanium equivalents. When you make stems this light available to the public, you don't want to leave things to chance.

LionelB wrote:
Good luck with your products. As a 6'5"/85kg rider I feel the Calnago feeling about super light parts, in particular stems. The lightest stem I used is the new Superlegerra, claimed at 100g, weighted at 120g for a 120mm...
Thanks, I appreciate your well-wishes. Though I'm only 6'0"/1m83 and around 70kg/155lbs, I can empathize with bigger and heavier riders.

For many years, I swore by my trusted Syntace Megaforce 260, a hefty and outdated model. I've worked with Deda stems and once tried a Newton 31.7 myself, but it didn't inspire the confidence I hoped for. Given my experience, a Superleggero simply wouldn't be my choice.

My view on this Deda model is that they made a lighter stem by omitting material but not actually improving overall ride characteristics. For what I expect a stem to do, I find the Superleggero rather lacking. I'm not saying it's a bad stem, since I think Deda made a decent effort that will please plenty of riders, plus there are lesser stems out there. Having worked with and on stems gave me the experience reflected in my design. I wouldn't mind to see the Superleggero included in a comparison test though.


Here are some of my personal views on stem stiffness. I differentiate between 2 types:
1) Torsional deflection, noticed when as pulling on one side of the bars and pushing on the other, and
2) Vertical movement, when pushing down on both sides, for example when riding over a bump or a hole

The biggest contributor to stem strength and stiffness I found to be the cross-section of the area between bars and fork. Both wall thickness and profile are important contributing factors. Strength comes from how a load is transferred through a structure and can be calculated through a load path. Smooth transitions between shapes allow surface stresses to diffuse as forces are exerted onto a structure.

The clamp areas around bars and fork are where many brands put more material in comparison to my design, so my stem has relatively more material in its barrel than the clamp areas. On my stem, due to a larger barrel, less material is needed for the clamp areas. Therefore, much weight is eliminated simply by changing one parameter, which simultaneously positively contributes to its rigidity. Part of the weight save equation is due to my proprietary bolt design. Lastly, stem length has a significant influence on stiffness.

When riding on cobbles or over rough terrain, you don't want your hands to be shaken off the bars or hoods. Though this is more the area of transmitted vibration/resonation. With my stem design, I chose a certain stiffness range as an absolute value at a reasonable weight of what 'feels' acceptable on a bike, while taking aesthetics into account.

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PostPosted: Mon Oct 07, 2013 5:05 pm 
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I think, as you are a small independent business this might be doable, that it would be neat if you could compare the stem stiffness wise to some equal competitors and showcase the numbers. Not to say your product is better, but so a potential customer might know what to expect.

I imagine you won't get a single customer who hasn't owned one or several of the big brand stems before, i.e Thomson 4X, 3T Arx, Deda Zero, Syntace F99/109, Extralite Ultra Stem, etc.

That would just be very informative, to know what if feels like. And ofcourse for various reasons big brand manufacturers can't really do this in an advertisement...

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PostPosted: Mon Oct 07, 2013 5:43 pm 
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mythical wrote:
My definition of a benchmark is simply something against which others are evaluated. It doesn't need to subject to bias.


Definition of benchmark: Benchmarking is the process of comparing one's business processes and performance metrics to industry bests or best practices from other industries

mythical wrote:
And the resources for the crankset development were neither my own nor from an investor. I'm just a poor guy who loves riding and found myself in a unique position to design some cool stuff. Let's not go off topic and stick to stems and stiffness.


Really?.....curious......ok, fair enough, back to the stem :D


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PostPosted: Mon Oct 07, 2013 6:48 pm 
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DMF wrote:
it would be neat if you could compare the stem stiffness wise to some equal competitors and showcase the numbers. Not to say your product is better, but so a potential customer might know what to expect.

And ofcourse for various reasons big brand manufacturers can't really do this in an advertisement...
Interesting standpoint. Out of curiosity, could you mention some of these reasons? Because I think it's done with frames and wheels, for example. Not that Wert Cycling has an advertising budget to begin with.

stephen@fibre-lyte wrote:
Definition of benchmark: Benchmarking is the process of comparing one's business processes and performance metrics to industry bests or best practices from other industries
Since we're on the subject of semantics, here's what my dictionary said:
benchmark |ˈbenCHˌmärk|
noun
1 a standard or point of reference against which things may be compared or assessed: [ as modifier ] : a benchmark case.
• a problem designed to evaluate the performance of a computer system: Xstones is a graphics benchmark.
2 a surveyor's mark cut in a wall, pillar, or building and used as a reference point in measuring altitudes.

verb [ with obj. ]
evaluate or check (something) by comparison with a standard: we are benchmarking our performance against external criteria | [ no obj. ] : we continue to benchmark against the competition.
• [ no obj. ] show particular results during a benchmark test: the device should benchmark at between 100 and 150 MHz.


Needless to say, none of us will deliberately put stems (or cranks) into walls. :wink:

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PostPosted: Mon Oct 07, 2013 7:30 pm 
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I meant in the form that I never see for example Trek claim "stiffer than a Cervélo, but not as stiff as a Felt". It's more along the lines of "15% stiffer than last years model", which isn't saying much if you haven't ridden last years model.

And I think that comes down to the poor taste in doing so with mainstream products. But I wouldn't really consider it in poor taste with such a niche product that targets an extremely niche group of customers, but that's just IMO ofcourse.

The direct comparisons I've seen all come from independent tests like Tour which the manufacturers seem to have very little to do with. Or atleast as far as I've seen it... But you never see magazine ad say "stiffer than that other similar brand". :)

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PostPosted: Tue Oct 08, 2013 8:26 pm 
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Actually, I'd like for Wert Cycling to become more mainstream than niche, possibly a few years down the road. If only people wouldn't regard weight so much, it might be easier, though it's out of place to ask that here, this being WW and all!

Stacking various stems up against each other surely would be interesting, and fun too. A methodology needs to be devised that eliminates deviations as much as possible. Things like dial gauges and weights I can easily obtain. Aside from measurements, a number of criteria need to be defined for final conclusions to be fair across the board. I've got some ideas of how to do this.

Stem samples, preferably in the same length and CEN-EN14781 or EN14766 approved, would need to be procured though usual distribution channels, since probably not many manufacturers, if any, are willing to contribute freely.

Madcow, if you're reading this, would you be up for it? :wink:

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PostPosted: Wed Oct 09, 2013 1:27 pm 
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As for a deflection test, I don't know if there is a difference but most (all?) tests tend to mount a bar or bar-like device in the stem bar clamp, fix the stem at a typical 73 degree angle as if on a bike, and hang weights vertically off the bar.

There may not be an actual difference so this is a valid method, but it seems to me that you never pull on a bar in this direction, in a sprint or a climb the pulling angle is rather facing backwards/upwards in a near 45 degree angle.

Might stems get different results for twisting/deflection if measurements were taken in this angle instead? Seems atleast it would be closer to real life. Ofcourse one could use the vertical weights method, just angle the stem to simulate this.

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Posted: Wed Oct 09, 2013 1:27 pm 


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