# billet bicycle wheel



## draganM (Nov 27, 2001)

Does anyone here know if a billet machined bicycle wheel has ever been attempted? The closest thing on the market today would be a Carbon disc or something like the old Spinergy's, the ones with full Carbon spokes, but without the associated failures and bankruptcy sales.
Spinergy Accidents - spinergy wheels

I know that re-inventing the wheel is a a potentially stupid and risky endeavor, I have been around for 20 years and have seen no end of new bicycle "wonder gear" come and go. however every wheel I've seen in my time has always been a compromise. 

1) traditional Spoked wheels/box section rim = heavy, aerodynamic nightmare, flexing and stretching of metal spokes and various junctions : cracking of J-ends, eyelets, etc. 

2)Carbon rimmed wheels w/spokes. Expensive to lay-up. Max rider limits of 225/250 imply a "fringe of durability" aspect . Braking problems/heat build up at rim edge. Race day only wheels.

3) Solid Carbon disc. similar to spoked / Carbon hooped wheels but heavier, cross wind problems.

I know these are crude generalizations but so many things would be solved with a billet Aluminum construction.
No steel spokes, nipples, or spoke junctions anywahere. No Carbon lay-up at all. Rim and Spokes would be one continuous piece of high grade Alloy. Extremely light weight. no breaking issues as the rim-spokes would have excellent thermal conductivity with spokes acting as a giant heat-sink. Has this been explored at all?

If you have no idea what i'm talking about, here';s the same approach with a motorcycle wheel. This was machined out of a single block . Notice how fragile this wheel "appears " to be, yet it's strong enough to support a motorcycle.

Mastercam Machines Motorcycle Wheels - YouTube


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## AndrwSwitch (May 28, 2009)

Weren't there some BMX wheels like that?

One of the keys, as I understand it, to the durability of the traditional bicycle wheel is that it's a pretensioned structure.

Another is that extrusion and forging are better ways to make stronger parts out of metal than cutting from a billet.

Have you seen how Mad Fiber wheels are made? I wonder if you could come up with a process in which the wheel was forged from aluminum, spokes and all, but planar. Cutting the forged hub apart and then widening it with a spacer would tension the spokes and bring it to the right OLD to go into a stock bike.

As a process, it would have plenty of problems. I think it would still be a race day wheel because it couldn't be trued. But hey, if you made it competitive enough in price and it looked cool...


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## JCavilia (Sep 12, 2005)

Seems like it would be heavy if it were strong enough, but I'm no engineer. I think you mis-state some of the disadvantages of spoked wheels. Aerodynamics is certainly an issue, as is the weak points of the many junctions. But my impression is that they are very light for their strength. And all that "flexing and stretching," if engineered right, is a good thing. Elasticity allows even lighter weight with great strength.


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## wim (Feb 28, 2005)

JCavilia said:


> Seems like it would be heavy if it were strong enough, but I'm no engineer.


I'm having the same thought. It would be interesting to have you cut two wheels out of a solid chunk of metal and see (1) if you can bring them in at around 1,600 gram for the pair and (2) if those 1,600-gram wheels cut out of a chunk of metal with the grain all going in the same direction will be strong enough to hold up under use.

Keep in mind that compared to a motorcycle or even a moped, power generation on a bicycle is frighteningly puny (even a strong sprinter can only produce about 1.5 hp for a brief time), so light weight is paramount both from a performance- and, ultimately, marketing perspective. 


/w


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## Urb (Jul 19, 2010)

So many reasons this isn't done. For one a motorcycle makes so much more HP than human legs could. The added strength is totally wasted, and your butt would be so sore as there would be zero vertical compliance. Added wieght as well. Gotta be some reason CF is the material of choice.


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## danl1 (Jul 23, 2005)

You are onto a million dollar idea.

Go spend a million on it, and report back on how many of those heavy, weak, anti-aerodynamic, un-repairable wheels you sell. 

You are correct that the bicycle wheel is a compromise. Every fine-edge high-performance thing is. Bicycle wheels - even the old-school stuff - are impressively strong, durable, repairable structures for their weight. 

But if you are interested in them in the spot on the bicycling continuum where they might have some market traction, it's been done.


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## wim (Feb 28, 2005)

danl1 said:


> But if you are interested in them in the spot on the bicycling continuum where they might have some market traction, it's been done.


Judging from where he posted his query, I think he's more interested in wheels for road ("race-type") bikes than clown bikes.


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## draganM (Nov 27, 2001)

danl1 said:


> You are onto a million dollar idea.
> Go spend a million on it, and report back on how many of those heavy, weak, anti-aerodynamic, un-repairable wheels you sell.


 a million dollars? LOL. I'm guessing you don't have a manufacturing/design background. Try $20K for all the equipment on the used market (which is currently bloated following the death of American industry).
That pic you posted is the same general idea, but more bicycle and less motorcycle. AFA heavy and un-aero, your basing that on that what? Do you have any idea how aero a 32 spoke wheel is?


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## DrSmile (Jul 22, 2006)

Bicycle wheels are made to be elastic. Billet wheels are about as opposite from that as you can get. I would expect a very harsh ride with a billet wheel, and I would expect the thin billet spokes to crack from the compression and tension stress cycling. A car and a motorcycle have a suspension system. On a road bike, that job is done by the spokes.

I'd still love to see a billet or forged road wheel with maybe 10 thin spokes. It would look pretty bling! If you have a CNC machine why not give it a shot? Only question is, do they make blocks big enough to make a 700cc wheel?


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## danl1 (Jul 23, 2005)

draganM said:


> a million dollars? LOL. I'm guessing you don't have a manufacturing/design background. Try $20K for all the equipment on the used market (which is currently bloated following the death of American industry).
> That pic you posted is the same general idea, but more bicycle and less motorcycle. AFA heavy and un-aero, your basing that on that what? Do you have any idea how aero a 32 spoke wheel is?


You are confusing machining with design. Sure, a CNC machine doesn't cost all that much - but one of the spec needed to hit the sort of tolerances you'd need to get to a competitive wheel (in all of it's shape-and-form glory) is going to be higher than you estimate - by a lot. One of the things you are likely forgetting is that along this route, the structure will begin to become considerably more flexible than a heavy motorcycle or clown-bike fashion wheel. That adds to the complexity and efforts required to keep it in tolerance. And the moment you take a serious look at the extruded rim structure you'd have to beat to compensate for the strength issues you will face in the spoke / disc portion of the program, you'll begin to understand. Maybe.

Where you'll spend millions - and fail - is in paying for the engineering (which you quite obviously don't have the vaguest idea about), trying to get your billet wheel to be even remotely competitive in any single performance parameter, let alone all of them - as compared to any reasonably modern deep-section, carbon-rimmed, traditionally-spoked wheel. 

A normal bicycle rim gains much of its strength by being held in uniform tension. To create a compressive structure of equal strength and stability, your rim will need to be much thicker and heavier than one on a traditional wheel. And because you'll be relying on compression rather than tension to hold the rim perpendicular to the axle, you'll need considerably more aluminum than a tension structure does. That's both heavy, and adds to the un-aerodynamic-ness of the design. if you seek to make them in a flat-spoke style similar to moto wheels, giving up on the tensioned structure's triangulation, you need to make the disc/spoke component quite thick - adding again to the weight, and killing crosswind performance (and BTW, most aero problems come because of off-axis wind.)

If there was a hope of making a wheel out of 'solid' aluminum (and it wouldn't be billet) it would be by using thin aluminum to create conical discs out of thin aluminum, weld them to more-or-less conventional rims, and getting clever at the hubs to put them into tension - similar to the Mad Fiber suggestion someone else made. But they'd be heavier and / or less strong (or in compromise, a bit of both) than a similar CF disc - and couldn't be given the finer sort of shaping that makes those discs so efficient.

If you try to make a true billet wheel, you'll lose on weight - not by percentages, but by multiples. You'll lose on aerodynamics by a significant margin, unless you like the upper parameter of that weight difference. You'll easily lose on strength, if you try to get within 2-3x on weight. 

But I really don't care if you choose to believe me. In fact, please don't. Please prove me wrong. To make it easy on you, let's assume you could have the rim be at the same weight as a conventional bike rim. (You can't for a couple of reasons, but let's keep this simple.) Calculate the weight of 28 steel spokes (use fewer if you'd like) and calculate how much aluminum that gives you to work with. Do a little simple geometry, and calculate how thick you could make two discs of that material. 

When you realize you are trying to make bicycle wheels out of something somewhere between beer cans and roof flashing, you'll hopefully realize the futility of this fantasy. It's not impossible to build a wheel in that manner, but it won't be aero, or light - and it will be impossible to machine. 

Perhaps you think I'm just talking out of my butt, and maybe I am. You shouldn't trust anything you read on the internet - just as I shouldn't believe that anyone is considering this notion in any sort of serious intellectual way. And I don't - I strongly suspect this is just senseless trolling. But sometimes it's fun to feed the trolls. Thanks for the entertainment.


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## draganM (Nov 27, 2001)

DrSmile said:


> I'd still love to see a billet or forged road wheel with maybe 10 thin spokes. It would look pretty bling! If you have a CNC machine why not give it a shot? Only question is, do they make blocks big enough to make a 700cc wheel?


 easily. Vendor in town specializing in large blocks. I feel like trying it, the front wheel at least would be an easy start and a good prototype. Not worried about it's shock absorbing ability, a Carbon disc can't be doing this very well either.


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## Lotophage (Feb 19, 2011)

It's a bad idea. 

AFAIK, there's no way you could make it lighter than a 32 spoke open pro. 

And, there'd be no way to true it. 

Without a doubt, it'd look cool as hell, but I can't see how you could machine a solid piece of aluminum into something lighter and stronger than a 32 spoke open pro.

Figure first, an open pro (and I'm just going with the OP because it's my go-to indestructible rim) is hollow in ways you can't cut billet aluminum and leave a brake track. 

then, figure spokes- the bigger they are, the more they're gonna weigh. I used to have a pair of spinergy carbon fiber wheels- 4 paired spokes, deep dish rim. They were pretty heavy. they looked cool, but they were heavy.

I think what you'd end up with would be pretty expensive due to the machine time and the sheer size of the chunk of aluminum it'd take. It would most likely be heavier than a standard wheel and it would be impossible to true, and probably even easier to damage than a regular wheel.

So if you really want to give it a shot, go for it, but there's gonna be a whole lot of testing before you'll convince anyone interested in performance alone to switch. 

That said, people have lined up to pay ridiculous prices for stuff that's heavier, impossible to fix and more expensive than it needs to be- just check out DI2.


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## Kuma601 (Jan 22, 2004)

Very easy to spend $250K+ on these VMC, HMC type CNC machining centers. You could buy aluminum plate than rough water jet cut them. Bolt them in and turn the machine on to run the program for the next 10-18 hours of machining time. 

Let's just throw some rough numbers: (I'm no longer in the biz and I didn't write up job estimates. This would be rough numbers gathered from different projects the shop had been involved, conservatively speaking.) 

A metal supplier randomly picked online:
MetalsDepot® - 3003 & 6061 Aluminum Plate

A 4'x4'x1.25" plate of 6061-T6 is x2 $4,656. 
Machine time billed at let's say $95/hour
Programming $100/hour and it say it takes 4 hours to compile the program. Not to mention the testing where there will be wastage until it is all dialed in. BTW you will pay for the materials. 
Machine time at 15 hours.
Manual labor for pre-finishing $65/hour
Any applied coatings-heat treat etc.

For 1 prototype set and one-off in a full run capability with no errors, you will hit $12K easily. If you want to make a profit, tack on as necessary. Of course after all this RD, to make it efficient you will need to make a run of X sets.


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## draganM (Nov 27, 2001)

well first off thanks for posting a thoughtful response without the insults, I don't mind criticism or questions, just the snarky attitudes which I guess you'll find on any forum.


Kontact said:


> As someone who's been around a lot of different types of machines using a variety of processes, why in the world would you select billet machining for something like a wheel? Especially if you expect it to be aerodynamic. Billet is a terrible start if you want a structure that is light and strong, and most of the billet parts I've seen are rarely as strong as their forged or otherwise formed counterparts, like stamping or extrusions.


 Good question. Forging followed by machining would be ideal, but this I believe would require and enormous investment. Same holds for true for stamping, the stamping dye would cost a fortune. Billet machining is so easy to manipulate and correct, even on the fly, with a CAD software model. There's no other approach that allows to stop, modify the design, and reload the G-codes while the part is clamped in the milling machine



Kontact said:


> If you wanted to make a tri-spoke out of metal, why wouldn't you make it like an metal bicycle frame out of tubular structures with welded, bonded, riveted or brazed joints? We know those structures are reasonably light and ductile, which a solid machined chunk is not going to be, aside from being an aerodynamic nightmare.


 I don't see how something this large could possibly be welded and kept even reasonably true, to the point where it could be fully trued by secondary machining operation. I also don't understand why this "aerodynamic nightmare" keeps coming up? You can mill the spokes, rim and hub to any shape you wanted. you could do something like this in 6 spoke design. Where the Carbon get it's strength from the large and hollow structure, with metal both the rim and spokes could be much smaller











Kontact said:


> The answer, BTW, is that even the lightest tubular metal wheel would still be noticeably heavier than a composite wheel and ride even worse. .


 sure, I realize that's likely. I know the aircraft industry is moving away from Metal towards composite for a reason. The Corima 3-soke pictured above is 770 grams.Still, I have the CAD/CAM software and feel like creating a file. IT won't tell me the weight but I bet I can get and engineer here to model that based on the CAD file.


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## draganM (Nov 27, 2001)

Kuma601 said:


> A metal supplier randomly picked online:
> MetalsDepot® - 3003 & 6061 Aluminum PlateA 4'x4'x1.25" plate of 6061-T6 is x2 $4,656. Machine time billed at let's say $95/hour Programming $100/hour and it say it takes 4 hours to compile the program. Not to mention the testing where there will be wastage until it is all dialed in. BTW you will pay for the materials..


 I rough measure a 700C wheel as 25" inch diameter , certainly don't need a 4 foot slug. I would machine this myself on weekends. Probably on a fixture I could load/unload quickly to keep the machine free for Monday morning.



Kuma601 said:


> Very easy to spend $250K+ on these VMC, HMC type CNC machining centers. You could buy aluminum plate than rough water jet cut them. Bolt them in and turn the machine on to run the program for the next 10-18 hours of machining time. .


 A used HAAS TM1 with a rotary table 4th axis used for $20K. Even with only 12 inches of travel in Y-axis you could machine the wheel in 3 parts by indexing it. I drew and machined this, did not take 18 hours. Even at only 4,000 rpm metal removal with AL is very rapid. Not to mention the big open areas between the spokes would come out very quickly as large slugs using a 3 flute hogging end mill, no water jet needed. You don't need a .003" step-over on the profiling either .01 or .02" would be fine both aesthetically and aerodynamically.
I realize the wheel would take longer, I'm guessing 8 hours per side including a form tool (key-way cutter) for the "clincher" portion of the rim.
Look guys I know this is a long shot, a VERY long shot. Still, I'm intrigued by it and feel like following through. Still, don't plan to stumble in completely blind.I have plenty of engineering here to draw on and get a second opinion based on a rough draft.


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## Urb (Jul 19, 2010)

Haven't done so myself but a cad program should be able to calculate the wieght of your model. For sure autocad does.

No idea why aero dynamics come into play. Welding has no place here when adhesives are far superior for bonding. 3d printing will make cnc milling look like a blacksmith hammering out horseshoes. No offence to blacksmiths, they are artists.

I wish you well in your research endeavor however I believe you will come to the same conclusion as everyone else is eluding too. Your product would be for a market for those who don't care about performance and willing to pay a premium price for the lack of it.


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## draganM (Nov 27, 2001)

like this, all 6 spokes are cupped with the hollow sides alternating. You would mill the 3 positive and the 3 negative profiles all from one side. Then flip the wheel and do the same thing on the other side. The spokes would not be on a flat plane , but slightly angled out towards the hub. Guessing around 2 to 3 millimeter wall thickness generally.


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## draganM (Nov 27, 2001)

Urb said:


> Haven't done so myself but a cad program should be able to calculate the wieght of your model. For sure autocad does.
> Your product would be for a market for those who don't care about performance and willing to pay a premium price for the lack of it.


 my program doesn't, but I could export the file and have someone do a quick calculation. Still, the 3D model will not be easy to draw.
I realize this would very likely be a novelty wheel for someone who wants to look like they're riding a very tricked out road bike and has the $3K or more to drop n wheels.
then again, there's that .005% chance it could turn out to be something that is relatively light, has half the deflection of a molded CF wheel, and is suitable for a track bike? It's too soon to predict with absolute certainty.


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## AndrwSwitch (May 28, 2009)

I don't think it would be too hard to model in Solidworks or something along those lines.

Are you thinking six aluminum compression spokes, or tension spokes? You'll need a lot more material if they're compression spokes, I think, but putting them in tension if you cut this thing out of a block is going to be a challenge.

Maybe start with a tubular rim if you're doing research/proof-of-concept.


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## Urb (Jul 19, 2010)

draganM said:


> then again, there's that .005% chance it could turn out to be something that is relatively light, has half the deflection of a molded CF wheel, and is suitable for a track bike?


The problem has never been making a stiff wheel with CF. This is a very easy thing to do. It's finding the threshold of rotational stiffness with vertical compliance or as you say deflection. Best you take a look at Mad Fibre before you commit to any cuts. Adding insult to injury the Mad Fibre wheels seems to use less material than your drawing with aluminum. You have one seemingly impossible battle ahead of you.

8 hours to machine per side? That's a lot of cost and time occupying your cnc machine. I think $3000 would be a very conservative cost estimation if you plan of turning a profit. Wouldn't it be better if you did what Performace Mmachine does with thier motorcycle wheels? Cut the "spokes" from aluminum sheet and bond them to a cnc'd rim? Hmm come to think of it this is what mad fibre does but with a much light and stronger material.

btw I'm a recreational cnc'r myself. I can appreciate your need to create and I wish you luck on your research.


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## DrSmile (Jul 22, 2006)

Negative nellies be damned, I say try it out and learn from the experience. According to Jack Hitt, it's the foundation of America!

Jack Hitt’s Bunch of Amateurs, reviewed. - Slate Magazine


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## Kontact (Apr 1, 2011)

draganM said:


> well first off thanks for posting a thoughtful response without the insults, I don't mind criticism or questions, just the snarky attitudes which I guess you'll find on any forum. Good question. Forging followed by machining would be ideal, but this I believe would require and enormous investment. Same holds for true for stamping, the stamping dye would cost a fortune. Billet machining is so easy to manipulate and correct, even on the fly, with a CAD software model. There's no other approach that allows to stop, modify the design, and reload the G-codes while the part is clamped in the milling machine
> 
> I don't see how something this large could possibly be welded and kept even reasonably true, to the point where it could be fully trued by secondary machining operation. I also don't understand why this "aerodynamic nightmare" keeps coming up? You can mill the spokes, rim and hub to any shape you wanted. you could do something like this in 6 spoke design. Where the Carbon get it's strength from the large and hollow structure, with metal both the rim and spokes could be much smaller
> 
> ...


Welded structures, like bike frames, can be very accurate. 

Carbon wheels aren't always hollow - some use thin "spokes". Whether you have thin spokes or a fat body has nothing to do with material - you have to provide side to side support for the rim via some sort of bracing angle. So if you want thin metal, they have to be offset and alternating at the hub. Ta-da! You've reinvented the spoked wheel, but your spokes aren't as light, aerodynamic or strong as drawn spokes, and you can't correct the wheel from use deformation.


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## Kuma601 (Jan 22, 2004)

Seems you are intent...go for it.


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## draganM (Nov 27, 2001)

Urb said:


> The problem has never been making a stiff wheel with CF. This is a very easy thing to do. It's finding the threshold of rotational stiffness with vertical compliance or as you say deflection. Best you take a look at Mad Fibre before you commit to any cuts. Adding insult to injury the Mad Fibre wheels seems to use less material than your drawing with aluminum. You have one seemingly impossible battle ahead of you..


 those MF wheels look like something for a 150 pound rider. I know they claim "no rider weight limit" but what happens after they break 2 weeks after warranty expires. They are not easily repairable either if at all.
I *believe* a billet AL wheel would be stronger, no joints, no seems, no material incompatibility's like you have between CF and AL etc. If you machined it true it would stay that way indefinitely short of a severe impact.


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## draganM (Nov 27, 2001)

AndrwSwitch said:


> I think, but putting them in tension if you cut this thing out of a block is going to be a challenge.Maybe start with a tubular rim if you're doing research/proof-of-concept.


It would not be tensioned like a metal spoked wheel built out of a loose hoop. However the bladed spokes would be opposing, both parallel and perpendicular to the axis of rotation. So loading the wheel side to side to side or top to bottom would put alternating spokes, in this case curved metal blades, in both tension and compression at the same time.


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## draganM (Nov 27, 2001)

thanks, the drawing itself is the first hurdle and i need to get the details right like the wheel diameter, bearings,the bladed spokes + how they transition from hub to rim. Whether to use 6 or 8, etc.


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## dave2pvd (Oct 15, 2007)

If I was you, I'd not bother with any more 2D drawing work. 

Get in touch with your SolidWorks buddy soon. Why draw this twice? 

Would you consider welding spokes to a ring? You will have distortion from TIG welding, but you could machine the ring into a rim _after _welding.


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## Urb (Jul 19, 2010)

draganM said:


> those MF wheels look like something for a 150 pound rider. I know they claim "no rider weight limit" but what happens after they break 2 weeks after warranty expires. They are not easily repairable either if at all.
> I *believe* a billet AL wheel would be stronger, no joints, no seems, no material incompatibility's like you have between CF and AL etc. If you machined it true it would stay that way indefinitely short of a severe impact.


Have you heard of cases where MF wheels broke? I haven't either. Perhaps their claim is true?

I think if you are to beat the competition you must understand the competition. In this case it's carbon fiber. 5 times stronger than steel and twice as stiff. As long as you don't exceed it's flex threshold it will last essential forever. Warranty is not a issue whatsoever here.

Lets deal with the intended market. People, as in humans. How much power can a human produce? 1000w? For arguments sake lets say 2000w. so roughly 2.6 hp. That is the power output you should be designing for. Adhesives are easily capable of bonding metal to CF in these tolerances. Easily.

Don't take my word for it. Go research carbon fiber yourself. I believe many of your statements and skepticism will change. Or don't.

I will say this is all very interesting and would be very cool if you should every cut a prototype.


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## AndrwSwitch (May 28, 2009)

draganM said:


> It would not be tensioned like a metal spoked wheel built out of a loose hoop. However the bladed spokes would be opposing, both parallel and perpendicular to the axis of rotation. So loading the wheel side to side to side or top to bottom would put alternating spokes, in this case curved metal blades, in both tension and compression at the same time.


The reason I mention tensioning the spokes is that part of what makes a traditional tension-spoked wheel work, and work so much better than a compression-spoked wheel is that pretensioning everything lowers the amplitude of the change in stress in the spokes. This means that less material can be used without screwing up the fatigue strength of the finished product.

Steel and carbon are both really tough competition because as long as a product is designed conservatively, it can be made to have an infinite lifespan in terms of fatigue. While aluminum can be made to have a very long lifespan, more than a person's lifespan if you like, you have to keep throwing more and more metal at the part to get that. Figure out a way to keep the stress amplitude under control and you don't need so much anymore.

I'm not sure how much formal engineering you have. I freely admit to being in the "a little knowledge is dangerous" stage of my education. But bicycle wheels are a pretty tricky problem, especially when subject to a fatigue load. Carbon composites are clearly changing things, but there's a reason that wire spokes under tension have been the structural element of almost all wheels for so long. The two big things a wheel needs to resist are fatigue, which steel is good, and the occasional really high peak load. But things have to be pretty burly to have the kind of fatigue characteristics that a bicycle wheel must have, so if you can figure out fatigue, you're probably already pretty close to having an acceptable safety factor for a rider on a real road.


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## maxxevv (Jan 18, 2009)

This I really have to see. 

To be frank, from engineering estimates, it will be extremely hard to approach 1kg (for a 700C front wheel) using a machined + welded wheel structure out of high grade aluminium. Assuming that is, its designed as something that can endure the rigors of normal riding as of any off the peg wheelset or rim you can find.


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## Kontact (Apr 1, 2011)

draganM said:


> It would not be tensioned like a metal spoked wheel built out of a loose hoop. However the bladed spokes would be opposing, both parallel and perpendicular to the axis of rotation. So loading the wheel side to side to side or top to bottom would put alternating spokes, in this case curved metal blades, in both tension and compression at the same time.


I was thinking more about this and thought I would try and illustrate the problem better.

An okay front wheel weighs around 700 grams with a 400 gram rim. That rim has the advantages of being an extruded tubular structure supported under tension every few inches.

A machined rim would have to be strong enough to take the load without tension and as a solid structure of slightly more brittle aluminum. I would guess the rim portion alone would need to weigh 700 or more grams because it is going to have to completely support itself.

If you're going to do that, why have multiple spokes at all? If the rim has to be that rigid, make it a two spoke wheel. But the whole thing is still going to weigh as much as a wheelset just for the front wheel.


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## draganM (Nov 27, 2001)

Kontact said:


> I was thinking more about this and thought I would try and illustrate the problem better.
> An okay front wheel weighs around 700 grams with a 400 gram rim. That rim has the advantages of being an extruded tubular structure supported under tension every few inches.
> A machined rim would have to be strong enough to take the load without tension and as a solid structure of slightly more brittle aluminum. *I would guess the rim portion alone would need to weigh 700 or more grams *because it is going to have to completely support itself..


ok, intersting approach. Lets look at it from a rim spoke junction/strength perspective. looking at the various parts separately in a traditional spoked wheel.
1) Hoop 400 grams. This is a double wall construction, in many cases with stainless steel eyelets, to support 32 * point loads* . In other words, there are 32 places where the load is concentrated in a very small area. Each nipple is 6mm diameter, roughly 5mm contacts the rim or .0314 sqaure inches. That's 1 square inch * total spoke/nipple to rim contact *on a 32 spoke wheel. At any given time your loading 5 spokes in the vertical plane while riding as the Hub "hangs, and pulls down on the rim. That's .157 inches of the rim handling the bulk of the load, 80% or more. This is why you need a 400g rim.

Now look at my rough sketch.Six 1" cross sections with full 1 inch radius on both sides of the blade. Lets take worst case scenario and you hit a pot-hole with only 1 spoke vertical, the way I drew it. The 2 adjacent would still take some of the load, maybe 20% guesstimate but lets take just one. with a 3mm blade thickness, each spoke has .24" rim contact. A 65% increase in rim-spoke contact area in this theoretical pot-hole scenario. The amount of material required for the rim itself would be* less*, not more. Without steel eyelets and double wall construction I wouldn't be surprised if the rim weight was cut in half.



Kontact said:


> A machined rim would have to be strong enough to take the load without tension and as a solid structure of slightly more brittle aluminum.


 Everyone keeps bringing up pre-tensioned as if it's a holy grail. Spokes *have* to be pre-tensioned because otherwise it's just a loose piece of wire. In a static mode, the pre-tensioning does nothing more than center the hub. Loads are created while riding, the riders weight and things he hits is why the load is created. Look at the pot hole again with a 32spk wheel. You hit it, the upper 5 spokes take a huge tension load. What are the 5 opposite spokes doing? They're now in compression, and actually working *against *you because they have not only zero ability to absorb the compression load but they're pre-tensioning is working to pull the hub downward. 
Look at my sketch. The 2 opposing spokes work in unison, not against each other. You hit the pot hole and the upper blade goes into tension, all .24 inches of it at the rim junction. The bottom opposing blade is now in compression which it *loves because it's a solid piece of metal*, not a stretched piece of wire.
so taking this tension/compression into play you actually have .48 inches of rim absorbing the load evenly as opposed to a spoked wheel. 
AFA being brittle, 6061 and 7075 Al alloys are *not *brittle, I machine them daily. The extruded rim sections you see in a typical hoop are made of very soft alloy that allows extruding. So soft it's difficult to machine, not unlike pure copper in some ways. 6061 is ductile yet has a much higher yield strength than the extruded stuff.





Kontact said:


> If you're going to do that, why have multiple spokes at all? If the rim has to be that rigid, make it a two spoke wheel. But the whole thing is still going to weigh as much as a wheelset just for the front wheel.


 I'm not interested in a disc. I would like to start with and create a 600 gram front wheel that is stronger than the molded Carbon "race day only" wheels out there now.


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## AndrwSwitch (May 28, 2009)

There was a thread a while ago where someone actually measured the changing tensile loads on a bicycle wheel. Turns out that the biggest change is actually at the bottom, where a few spokes experience reduced tension. Weird, huh?

Solids aren't great for lateral rigidity. The core of a member doesn't do all that much, but it still has mass. You need to either put some angle on some thin members, similar to how spokes angle outward from the rim to the hub or what Mad Fiber is doing, or have something wide and hollow, like a three-spoke carbon wheel.

There's actually a fair amount of literature out there on wheels. I think it's possible to come up with a better design, certainly, but do some research, and maybe read through the old patents. A surprising amount of current bicycle technology is old patents recycled with materials or techniques that weren't available at the time. Some ideas were good, weren't feasible at the time, and are feasible now.


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## draganM (Nov 27, 2001)

dave2pvd said:


> If I was you, I'd not bother with any more 2D drawing work.
> Get in touch with your SolidWorks buddy soon. Why draw this twice? .


 I'm using old mastercam Version 9 2-D with surfacing ability. So i Can apply a surface to a wire-frame and even blend them together. However it's not ideal.
I need to get the Version-13 in my desk drawer going though. It's full 3D and unlike solid works has a CAM version to generate tool-paths. 



dave2pvd said:


> Would you consider welding spokes to a ring? You will have distortion from TIG welding, but you could machine the ring into a rim _after _welding.


 true, I could start with a raw solid- box section AL ring and a rough machined AL chunk with small flanges for the hub. Then Take some large diameter AL tubing and cut it up like barrel stave's into curved bladed spokes. Weld everything together, then finish-machine the hoop and hub concentric. the difficulty would be getting all 6 spokes evenly spaced to avoid an out of balance wheel. You would really need a large fixture with indexing pins to hold everything in place while welding. Even then the balancing would not be perfect unless you were very good with TIG, i'm only OK, I can wled gas tight stainless but it's not the same as a beautiful "bike quality" weld.
Worst of all, Seems like more work for me and less for the machines


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## Kontact (Apr 1, 2011)

draganM said:


> ok, intersting approach. Lets look at it from a rim spoke junction/strength perspective. looking at the various parts separately in a traditional spoked wheel.
> 1) Hoop 400 grams. This is a double wall construction, in many cases with stainless steel eyelets, to support 32 * point loads* . In other words, there are 32 places where the load is concentrated in a very small area. Each nipple is 6mm diameter, roughly 5mm contacts the rim or .0314 sqaure inches. That's 1 square inch * total spoke/nipple to rim contact *on a 32 spoke wheel. At any given time your loading 5 spokes in the vertical plane while riding as the Hub "hangs, and pulls down on the rim. That's .157 inches of the rim handling the bulk of the load, 80% or more. This is why you need a 400g rim.
> 
> Now look at my rough sketch.Six 1" cross sections with full 1 inch radius on both sides of the blade. Lets take worst case scenario and you hit a pot-hole with only 1 spoke vertical, the way I drew it. The 2 adjacent would still take some of the load, maybe 20% guesstimate but lets take just one. with a 3mm blade thickness, each spoke has .24" rim contact. A 65% increase in rim-spoke contact area in this theoretical pot-hole scenario. The amount of material required for the rim itself would be* less*, not more. Without steel eyelets and double wall construction I wouldn't be surprised if the rim weight was cut in half.
> ...


I don't think you really understand how a wheel works, and are completely forgetting about what the alternating braced spokes are doing to support both vertical loads and side loads. The spokes aren't just under tension - the rim is under compression from the spokes.

Additionally, you are missing my point that your "rim" isn't hollow, so it has to derive all it's strength from wall thickness, and you want it to be lighter than a hollow rim and support spans between braced spokes that are much larger. That requires more, not less material.

Basic light rims are so strong that the spokes will break from increased tension before the spoke hole will crack. But they are not strong enough to bear rider weight no tension on the spokes. That's because the finished wheel distributes loads throughout the wheel due to pretenioned spokes running back to the hub, rather than the simple opposing spoke theory you're basing this on.

I don't see how you could possibly make even a solid machined rim at 600 grams that would be as strong as a hollow 400 gram rim, let alone a whole wheel. All those little spoke holes aren't a problem, they're the reason a rim I could crush with my hands will support a 400 pound rider once tensioned. How is a lighter, less rigid solid structure going go support 12" spans between spokes when a hollow rim can't?


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## draganM (Nov 27, 2001)

AndrwSwitch said:


> There was a thread a while ago where someone actually measured the changing tensile loads on a bicycle wheel. Turns out that the biggest change is actually at the bottom, where a few spokes experience reduced tension. Weird, huh?


 exactly, they go into compression mode while riding. huge problem



AndrwSwitch said:


> Solids aren't great for lateral rigidity. The core of a member doesn't do all that much, but it still has mass. You need to either put some angle on some thin members, similar to how spokes angle outward from the rim to the hub or what Mad Fiber is doing, or have something wide and hollow, like a three-spoke carbon wheel.


 vertically the billet wheels is excellent, the lateral is a concern. Instead of fully hollow the plan was to use curved bladed sections and do some angling out towards the hub


AndrwSwitch said:


> There's actually a fair amount of literature out there on wheels. I think it's possible to come up with a better design, certainly, but do some research, and maybe read through the old patents. A surprising amount of current bicycle technology is old patents recycled with materials or techniques that weren't available at the time. Some ideas were good, weren't feasible at the time, and are feasible now.


 very good advice and I don't plan to just start cutting metal blindly


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## AndrwSwitch (May 28, 2009)

draganM said:


> exactly, they go into compression mode while riding. huge problem


I don't think you understood me here. They don't go into compression, they're still in tension. They just experience the biggest change in total force. That's why pre-tensioning is such a big deal - if they were actually in compression, the system wouldn't work.


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## Kontact (Apr 1, 2011)

draganM said:


> exactly, they go into compression mode while riding. huge problem
> 
> vertically the billet wheels is excellent, the lateral is a concern. Instead of fully hollow the plan was to use curved bladed sections and do some angling out towards the hub
> very good advice and I don't plan to just start cutting metal blindly


The spokes never compress, they just reduce tension. A spoked wheel is a round hoop that is trying to turn into an oval under rider weight. The bottom of the wheel is supported by the fact that the rim 90 away can't increase its distance from the hub because of the spoke tension. That's the rim compression I mentioned.

Also, you've mentioned curved spokes. How is curving the spoke going to help? The curve will just increase the ability of the spoke to compress and elongate.


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## draganM (Nov 27, 2001)

maxxevv said:


> This I really have to see.
> 
> To be frank, from engineering estimates, it will be extremely hard to approach 1kg (for a 700C front wheel) using a machined + welded wheel structure out of high grade aluminum. Assuming that is, its designed as something that can endure the rigors of normal riding as of any off the peg wheelset or rim you can find.


 what engineering estimates?
hub, roughly 110 grams. each bladed spoke roughly 60grams. that's 470 not including the rim. You sure as heck aren't going to need a 400 gram rim with stainless steel eyelets.
My guesstimate is more than 600 grams and less than 700.


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## Kontact (Apr 1, 2011)

draganM said:


> what engineering estimates?
> hub, roughly 110 grams. each bladed spoke roughly 60grams. that's 470 not including the rim. You sure as heck aren't going to need a 400 gram rim with stainless steel eyelets.
> My guesstimate is more than 600 grams and less than 700.


How light do you think you can make a solid rim that is able to support long spans with no support?

400 gram rims don't have eyelets, usually. The lightest clincher rims are 380 or so. And as I said earlier, the strength of the spoke hole is not the limiting feature of a rim.


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## draganM (Nov 27, 2001)

Kontact said:


> I don't think you really understand how a wheel works, and are completely forgetting about what the alternating braced spokes are doing to support both vertical loads and side loads. The spokes aren't just under tension - the rim is under compression from the spokes.


 interesting point. Yes, the hoop is under both tension radially as the spokes pull on it, and in compression axially as it tries to "collapse" upon itself. What happens when you hiot something?
the spokes stretch, I don't care how thick they are they will stretch. What happens to your perfect symmetrical wheel now? The bottom spokes become loose for a very short period of time, the tension increases on the upper spokes, and the compression forces on the rim also shift unevenly, then it all comes back. Now you can argue that this "give" is what makes a spoked wheel last a long time but it also makes for a wheel which flexes radially and side to side as well and that flex translates to loss of pedaling energy being transfered to the ground.


Kontact said:


> Basic light rims are so strong that the spokes will break from increased tension before the spoke hole will crack. But they are not strong enough to bear rider weight no tension on the spokes. That's because the finished wheel distributes loads throughout the wheel due to pretenioned spokes running back to the hub, rather than the simple opposing spoke theory you're basing this on.


 well in my experience this is just not true. My last rim cracked all around the spokes, in many places at once and it thankfully since it was metal it happened gradually and not instantly. Mavic open4 rim with double wall eyelets. Many of the eyelets split in half too.



Kontact said:


> I don't see how you could possibly make even a solid machined rim at 600 grams that would be as strong as a hollow 400 gram rim, let alone a whole wheel. All those little spoke holes aren't a problem, they're the reason a rim I could crush with my hands will support a 400 pound rider once tensioned. How is a lighter, less rigid solid structure going go support 12" spans between spokes when a hollow rim can't?


 you cannot crush a rim with your hands, I can't believe you wrote this? have you ever even built a wheel? I can put all of my 200 pound weight down on a 400 gram hoop, just a bare hoop, and it will support me. I can't even flex it. I know this as that's exactly what I did when I replaced the last open 4 hoop. Every rim I've ever owned in 20+ years of riding and racing cracks eventually at the rim-spoke juncture, plain and simple. So much so that my current rim is using the same spokes in the same lacing pattern from the previous wheel. I've replaced the rim twice, sheared off a few nipples, but the spokes themselves have lasted over 10K miles.


Kontact said:


> Additionally, you are missing my point that your "rim" isn't hollow, so it has to derive all it's strength from wall thickness, and you want it to be lighter than a hollow rim and support spans between braced spokes that are much larger. That requires more, not less material.


 good point, a hollow box section adds a lot of strength, even where it's not needed.
The answer is I can machine the strength into the rim exactly where it's needed. Notice the big 1 inch radius's in the quick sketch I made. Once this is drawn in 3D it will show the blades don't just but up to the rim in a flat plane. They are curved and will _ flow _together using a gradual radius in all planes. This will distribute both the tension and compression loads outward over a much greater area.
In other words, unlike a traditional spoked bicycle wheel, the rim on a billet wheel is not under tension or compression while in a static situation. The rim is almost entirely there to keep the 6 spokes from moving and evenly spaced from each other. Even when a load is applied off axis to the spokes, it will be carried by the spokes almost exclusively which unlike a wire spoke, will have considerable strength along their axis. 
the rim here can be very thin the same way an arched bridge made out of thin metal plates can support huge loads and transfer them directly to the Abutments on either end. Here's a simple force vectoring sketch off axis. *I don't need a strong rim*


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## Kontact (Apr 1, 2011)

draganM said:


> interesting point. Yes, the hoop is under both tension radially as the spokes pull on it, and in compression axially as it tries to "collapse" upon itself. What happens when you hiot something?
> the spokes stretch, I don't care how thick they are they will stretch. What happens to your perfect symmetrical wheel now? The bottom spokes become loose for a very short period of time, the tension increases on the upper spokes, and the compression forces on the rim also shift unevenly, then it all comes back. Now you can argue that this "give" is what makes a spoked wheel last a long time but it also makes for a wheel which flexes radially and side to side as well and that flex translates to loss of pedaling energy being transfered to the ground.
> well in my experience this is just not true. My last rim cracked all around the spokes, in many places at once and it thankfully since it was metal it happened gradually and not instantly. Mavic open4 rim with double wall eyelets. Many of the eyelets split in half too.
> 
> ...


I have built so many I can't remember, and I work for the guy who invented and patented the Crono wheel that Cane Creek sold for many years. So part of what I'm telling you about spoke hole strength and rim strength is from the actual design studies that created that wheel system. The Mavic rim you reference has gotten a pretty so-so reputation, but work hardening like your's did is different than pull-through strength, and is partially a function of build tension - lighter tensions increase the work hardening because the tension delta is greater when riding than higher tensions.

My biggest point is that you don't seem to think that rims don't have to be strong for long spans between spokes. My boss and I were talking about this, and his study showed that decreased spoke counts went along with rim height - tall rims can go further between spokes without collapsing.

But you can't do a tall section rim because you don't have the ability to carve a large, hollow section. All you can do is make the equivalent of a super shallow box section rim - the weakest kind of rim for low spoke counts. 

In your diagram, that kind of weak, shallow rim would just dent in where you have the compression arrow. Even with the radius you show off the spoke, you have at least 10" of unsupported rim. Why don't you think you need a strong rim?


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## RHankey (Sep 7, 2007)

draganM said:


> interesting point. Yes, the hoop is under both tension radially as the spokes pull on it, and in compression axially as it tries to "collapse" upon itself. What happens when you hiot something?
> the spokes stretch, I don't care how thick they are they will stretch. What happens to your perfect symmetrical wheel now? The bottom spokes become loose for a very short period of time, the tension increases on the upper spokes, and the compression forces on the rim also shift unevenly, then it all comes back. Now you can argue that this "give" is what makes a spoked wheel last a long time but it also makes for a wheel which flexes radially and side to side as well and that flex translates to loss of pedaling energy being transfered to the ground.


A properly tensioned wheel will never have any spokes go loose at any time, not even when hitting a bump. The strength of a properly tensioned wheel is that all the forces are spread as evenly around the wheel as possible – even the spokes on the bottom side of the wheel contributing. If you want to see what happens if spokes in a wheel can change between tension, unloaded, and compression, perhaps you might want to read up on some of the Mavic R-Sys wheel failures.

If your rims are continuously failing at multiple spoke holes, then they are tensioned too high for that of the rim, or need washers to spread the load out some more.

Most modern clincher rims can probably support an average person’s weight without any spokes, but there used to be a number of older low profile Al box rims for tubulars that wouldn’t take much weight to bend them without spokes. Even with those rims, the notion of doing so bare handed to an uncompromised rim is likely a bit of an exaggeration unless you are bit of a gorilla. Many decades ago, tubular rims used to be made from wooden hoops, that without spokes could likely be easily broken bare handed.

I’ve ridden some pretty stiff and harsh riding composite or disk wheels over the years, but the billet wheels you are contemplating building are likely to give a whole new meaning to harsh if they are to have any longevity. I commend your open mindedness. Give it a try and see what happens.


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## maxxevv (Jan 18, 2009)

draganM said:


> what engineering estimates?
> hub, roughly 110 grams. each bladed spoke roughly 60grams. that's 470 not including the rim. You sure as heck aren't going to need a 400 gram rim with stainless steel eyelets.
> My guesstimate is more than 600 grams and less than 700.


My day job is in mechanical engineering design. Its been my job for more than a decade. I certainly know how much a structure should weigh with an estimated volume and profile weighs approximately. 

Not that I want to diss you, in fact I applaud the courage but I certainly don't wish to lead you down a blind alley if I can prevent it. There are good reasons why certain things are not done, perhaps you should read up a little on how structures are optimized, especially wheels. There is plenty of good reasons why the London Eye and the Singapore Flyer (the 2 biggest wheel structures in the world) are build that way ( though the dynamic loads are a little different)... And there's plenty of literature on the mechanics of a bicycle wheel too. 

Perhaps you would like to do a full-scale CAD model and estimate the weight of the wheel based on your design and then do a FEM analysis ( which is actually very complex for pre-tensioned structure like a modern wheel) , iterate the process a few times to optimise between weight and strength and see how close your weight estimates are ? Material volume and density are inescapable quantities once you have a full, detailed CAD model. 

I would certainly like to see you proven right. :thumbsup:


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## cxwrench (Nov 9, 2004)

draganM said:


> * you cannot crush a rim with your hands*, I can't believe you wrote this? have you ever even built a wheel? I can put all of my 200 pound weight down on a 400 gram hoop, just a bare hoop, and it will support me. I can't even flex it. I know this as that's exactly what I did when I replaced the last open 4 hoop. Every rim I've ever owned in 20+ years of riding and racing cracks eventually at the rim-spoke juncture, plain and simple. So much so that my current rim is using the same spokes in the same lacing pattern from the previous wheel. I've replaced the rim twice, sheared off a few nipples, but the spokes themselves have lasted over 10K miles.


i've build hundreds and hundreds of wheels, and i'll absolutely agree w/ him. you can easily destroy a rim by hand. i've done it dozens of times before throwing out cracked rims. it's surprisingly easy...if you don't think it's possible, you don't have a clue. if every wheel you've ever owned has cracked at the spoke holes at some point, i'd find a new wheel builder. or use different rims. that should not be happening like you say.


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## draganM (Nov 27, 2001)

maxxevv said:


> Perhaps you would like to do a full-scale CAD model and estimate the weight of the wheel based on your design and then do a FEM analysis ( which is actually very complex for pre-tensioned structure like a modern wheel) , iterate the process a few times to optimise between weight and strength and see how close your weight estimates are ? Material volume and density are inescapable quantities once you have a full, detailed CAD model.
> 
> I would certainly like to see you proven right. :thumbsup:


 your right max, at this point a full 3D CAd model is required. It will not be easy but then again no metal needs ot be cut and no tooling made. Using only software, good data will be revealed on whether this is worth pursuing or pure Foobar. I'm an optimist and give it a 30% chance of success


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## draganM (Nov 27, 2001)

AndrwSwitch said:


> I don't think you understood me here. They don't go into compression, they're still in tension. They just experience the biggest change in total force. That's why pre-tensioning is such a big deal - if they were actually in compression, the system wouldn't work.


 they experience a compressive load. Whether or not the spoke actually ever loses all it's pre-tensioning I do not know. I have read articles that claim under a very hard hit they can go slack, do they every get shoved into the rim strip, doubtful but to say they are *always* in tension seems unlikely to me.
Anyway, I don't care about spoked wheels.  They were were a miracle in their day when spoked wheels originally meant wooden spokes in metal hoop drawn by Oxen. The fact that they're still around is a testament to the genius of the original design. However I'm having a hard time accepting that design and carbon wheels as the only possibility for road bikes and plan to explore this further.
It might take me a few months, but I will come back with a full 3D Cad model. Until then, and no offense to your work with Cane creek, there is too much conjecture and opinion.


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## Kontact (Apr 1, 2011)

draganM said:


> they experience a compressive load. Whether or not the spoke actually ever loses all it's pre-tensioning I do not know. I have read articles that claim under a very hard hit they can go slack, do they every get shoved into the rim strip, doubtful but to say they are *always* in tension seems unlikely to me.
> Anyway, I don't care about spoked wheels.  They were were a miracle in their day when spoked wheels originally meant wooden spokes in metal hoop drawn by Oxen. The fact that they're still around is a testament to the genius of the original design. However I'm having a hard time accepting that design and carbon wheels as the only possibility for road bikes and plan to explore this further.
> It might take me a few months, but I will come back with a full 3D Cad model. Until then, and no offense to your work with Cane creek, there is too much conjecture and opinion.


I think it's cool that you're interested in this, but the conjecture is decidedly on your side of the aisle. You've gotten a lot of experienced wheel builders weighing in on this thread, but you have an entirely different set of beliefs, and I can't tell where they come from.


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## draganM (Nov 27, 2001)

Kontact said:


> I think it's cool that you're interested in this, but the conjecture is decidedly on your side of the aisle. You've gotten a lot of experienced wheel builders weighing in on this thread,


 yup, lots of *wheel builders *, not so many wheel designers. Lacing up a wheel doesn't make one an engineer. Granted the Engineers are saying this is unlikely, not impossible, but highly unlikely. Thats OK
At any rate, a 3D CAD model is simply strokes on a keyboard. It's not like I'm going ot lose anything by doing it. On the contrary success, failure, or something in between I will learn something valuable that can only make me better at my day job.


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## Kontact (Apr 1, 2011)

draganM said:


> yup, lots of *wheel builders *, not so many wheel designers. Lacing up a wheel doesn't make one an engineer. Granted the Engineers are saying this is unlikely, not impossible, but highly unlikely. Thats OK
> At any rate, a 3D CAD model is simply strokes on a keyboard. It's not like I'm going ot lose anything by doing it. On the contrary success, failure, or something in between I will learn something valuable that can only make me better at my day job.


And if you're good with CAD software it will go pretty quick.

However, if you start your model with erroneous data - like low profile rims being self supporting - the model you get won't be very meaningful. You'll have to actually build it and go take it down a bumpy road to see what a week rim with a high pressure tire will do when it has huge unsupported spans.


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## draganM (Nov 27, 2001)

Kontact said:


> You'll have to actually build it and go take it down a bumpy road to see what a week rim with a high pressure tire will do when it has huge unsupported spans.


 no you really don't. I have a ME friend who would be glad to run FEA software on the model once it's drawn. That will show exactly where more material is needed and where it isn't.
That span will not be un-supported. Maybe better to wait and see what it looks like before assuming so many things based on a 2-D sketch I did in 10 minutes for the sake of conversation.


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## AndrwSwitch (May 28, 2009)

Hopefully your ME friend won't be too proud to tell you a bit about the limitations of FEA.

Granted, I'd probably just test a FEA model in four spots, especially if it was just a favor for someone. But still.

I bet you end up with a design that looks kind of like a BMX chainwheel with big cutouts. Which would look pretty badass.


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## Kontact (Apr 1, 2011)

draganM said:


> no you really don't. I have a ME friend who would be glad to run FEA software on the model once it's drawn. That will show exactly where more material is needed and where it isn't.
> That span will not be un-supported. Maybe better to wait and see what it looks like before assuming so many things based on a 2-D sketch I did in 10 minutes for the sake of conversation.


Actually, I'm basing this on your assertion that you need even less material than a 400 gram rim, since those would collapse despite having the advantage of being hollow.


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## maxxevv (Jan 18, 2009)

draganM said:


> your right max, at this point a full 3D CAd model is required. It will not be easy but then again no metal needs ot be cut and no tooling made. Using only software, good data will be revealed on whether this is worth pursuing or pure Foobar. I'm an optimist and give it a 30% chance of success


Building it would be tricky even if you can model it.


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## morgan1819 (Nov 22, 2005)

I predict that you will have 100% success building a wheel using the methods you have described.

I also predict that :

A.) the wheel will be heavier than what is acceptable to most riders, and 

B.) be suitable only for smooth surfaces.


I actually think it's cool you are attempting this, and wish you the best of luck.

I also give you credit for acknowledging that this may, in fact, be a stupid and risky endeavor.

You mention strength-to-weight ratio, and aerodynamics as areas in which you hope to improve on. Even if you were to somehow miraculously succeed at one, or both of those ... if the wheel rides like a brick, it is essentially worthless.

Another thing to ponder: Mavic has had some well publicized failures in their aluminum spoke designs, and the problem wasn't at the spoke/rim juncture. If anyone has the resources to make an aluminum spoke work, it would be Mavic.

After a few billion test miles, the steel spoke has proven to be the ideal material for mating a hub to a rim. We've seen infinite theories as to the reason why ... I won't get into that.


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## AndrwSwitch (May 28, 2009)

Because steel is close to being the ultimate engineering material!  Other things might have it beat on strength/weight, but otherwise, nobody would ever build with anything else.


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