eeWings, Craig and Cane Creek's revived Sweetwings
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Sort of.
400g
Sram direct chaining mount
Hirth joint
3al2.5v arms, 6al4v spindle and bosses
https://m.pinkbike.com/news/cane-creek- ... -look.html
Should be easier to get a set than Propellers, as my local Cane Creek distro has listed it on their b2b already and apparently the first production run is sold out nearly entirely to distributors.
My opinion:
They're nearly the exact crank I would build if I were in a position to do so.
400g
Sram direct chaining mount
Hirth joint
3al2.5v arms, 6al4v spindle and bosses
https://m.pinkbike.com/news/cane-creek- ... -look.html
Should be easier to get a set than Propellers, as my local Cane Creek distro has listed it on their b2b already and apparently the first production run is sold out nearly entirely to distributors.
My opinion:
They're nearly the exact crank I would build if I were in a position to do so.
Last edited by FreaK on Wed Apr 18, 2018 11:52 pm, edited 1 time in total.
it's actually possible to come to the conclusion even before realising it makes no sense at all
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tymon_tm
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tymon_tm
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Hoping for a *steel* road BSA version!
Appreciate the originality but it can't be competitive in terms of stiffness to weight ratio. In flexion and torsion Titanium Young modulus and density are clear on this matter And don't see any design change that would compensate this.
Anticipating comments:
- Ti aloys have little stiffness variation then it can't compensate material limitations.
- stiffness do matter, flex at one point of the pedal stroke is not usable to "spin" the cranks at the end of the stroke.
Now I can't deny it is a beautiful product.
Edit: reacted as road cyclist, just realised it is the MTB forum... the impact resistance claimed could be a plus but the welds represent a weaker point so...
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Anticipating comments:
- Ti aloys have little stiffness variation then it can't compensate material limitations.
- stiffness do matter, flex at one point of the pedal stroke is not usable to "spin" the cranks at the end of the stroke.
Now I can't deny it is a beautiful product.
Edit: reacted as road cyclist, just realised it is the MTB forum... the impact resistance claimed could be a plus but the welds represent a weaker point so...
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I suspect the reason it's taken so goddamn long for a 'mainstream' version has been because there's a known issue around welded ti cranks.
I suspect the crossection of the arms is plenty to compensate for material choice. They are very very chunky. In steel they would obviously be far stiffer.
I suspect the crossection of the arms is plenty to compensate for material choice. They are very very chunky. In steel they would obviously be far stiffer.
Last edited by FreaK on Wed Apr 18, 2018 11:46 pm, edited 1 time in total.
it's actually possible to come to the conclusion even before realising it makes no sense at all
-
tymon_tm
-
tymon_tm
The shape can bring stiffness but the stw ratio would remain lower than the same shape in aluminium. Just that Ti has lower specific stiffness in torsion and flexion. That's putting a lot of efforts to design something with a material with lower performance index for this application.FreaK wrote:I suspect te reason it's taken so goddamn long for a 'mainstream' version has been because there's a known issue around welded ti cranks.
I suspect the crossection of the arms is plenty to compensate for material choice. They are very very chunky. In steel they would obviously be far stiffer.
Now they look cool
The whole EE cranks saga, so to speak, has relied on aluminium designs, and has not led to a commercially available product. There are clearly a few reasons for that.
Comparing materials used in a crank by mass is essentially useless as crank design is a exercise in volume management. Mass is secondary. It's like saying a Ti frame "cannot" be stiff. That's fairly absurd.
Comparing materials used in a crank by mass is essentially useless as crank design is a exercise in volume management. Mass is secondary. It's like saying a Ti frame "cannot" be stiff. That's fairly absurd.
it's actually possible to come to the conclusion even before realising it makes no sense at all
-
tymon_tm
-
tymon_tm
Not sure if that was for me but i never mentioned mass but stiffness to weight ratio, material stiffness (young modulus) and density. For example there is not a single chance on earth to have a competitive stw ratio on a Ti frame (but could be competitive on other aspect, confort, durability...). I would say it is the same here. Even if result end up acceptable, ohter materials would have been more performant.FreaK wrote:The whole EE cranks saga, so to speak, has relied on aluminium designs, and has not led to a commercially available product. There are clearly a few reasons for that.
Comparing materials used in a crank by mass is essentially useless as crank design is a exercise in volume management. Mass is secondary. It's like saying a Ti frame "cannot" be stiff. That's fairly absurd.
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I'm not sure what you're trying to say here, C36. You say a Ti frame can't possibly have a competitive stiffness-to-weight ratio. But compared to what?C36 wrote: ↑Thu Apr 19, 2018 12:18 amNot sure if that was for me but i never mentioned mass but stiffness to weight ratio, material stiffness (young modulus) and density. For example there is not a single chance on earth to have a competitive stw ratio on a Ti frame (but could be competitive on other aspect, confort, durability...).FreaK wrote:Comparing materials used in a crank by mass is essentially useless as crank design is a exercise in volume management. Mass is secondary. It's like saying a Ti frame "cannot" be stiff. That's fairly absurd.
Besides, most metals used for bicycles have essentially the same stiffness (modulus) to weight (density) ratio. In units of gigaPascals / grams per cm^3, those ratios break down like this:
4130 steel: 26.12
Ti 6Al/4V: 25.73
7075 aluminum: 25.52
Magnesium: 25.29
You can see that each of these is within 1.5% of the values above or below, and most of them are within 1%. A material's stiffness-to-density ratio is not really something that matters so much when trying to make something light and/or stiff.
There's a reason most frames are CF nowadays
My main ride is still titanium though for various reasons.
Hell yes it matters! The ratio you listed is valid in traction (E/density). Flexion performance index is (SquareRoot E / density) then your perf index is:youngs_modulus wrote:I'm not sure what you're trying to say here, C36. You say a Ti frame can't possibly have a competitive stiffness-to-weight ratio. But compared to what?C36 wrote: ↑Thu Apr 19, 2018 12:18 amNot sure if that was for me but i never mentioned mass but stiffness to weight ratio, material stiffness (young modulus) and density. For example there is not a single chance on earth to have a competitive stw ratio on a Ti frame (but could be competitive on other aspect, confort, durability...).FreaK wrote:Comparing materials used in a crank by mass is essentially useless as crank design is a exercise in volume management. Mass is secondary. It's like saying a Ti frame "cannot" be stiff. That's fairly absurd.
Besides, most metals used for bicycles have essentially the same stiffness (modulus) to weight (density) ratio. In units of gigaPascals / grams per cm^3, those ratios break down like this:
4130 steel: 26.12
Ti 6Al/4V: 25.73
7075 aluminum: 25.52
Magnesium: 25.29
You can see that each of these is within 1.5% of the values above or below, and most of them are within 1%. A material's stiffness-to-density ratio is not really something that matters so much when trying to make something light and/or stiff.
- Steel 1.9
- Aluminium 3.1
- Ti: 2.4
In torsion the differences are even larger. Now in all cases you need to factor other parameters like manufacturing (wall thickness limits) or strength (not a problem for Al, Ti or steel but could be the case for magnesium for example), will stop there or could talk about it four hours .
For the Ti frames, "compared to what?" Well compared to other materials, aluminium for example (carbon being anisotropic you can't generalise).
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the cane creek are a bargain then? http://www.bike-magazin.de/mtb_news/tei ... 34351.html
Not really sure what 3D printing would bring for a component that has a "fairly" simple shape and no real volume constraint, the performance index of Ti would remain lower in terms of stw. That's just not an application where you need titanium...Ravnsnaes wrote:They can definitely make titanium cranks to rival carbon and aluminium cranks in terms of stiffness and weight. The answer is ofcourse: 3D printing. (But the price would be in the thousands of $).
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