# Risks



## pvd (Jan 4, 2006)

Hey folks,

I figured I'd share this as it doesn't get talked about much. Few mention their failures or problems. On Saturday, I had one shining example of what can go wrong when we push the limits.

Dunkirk | Peter Verdone Designs










The bike is pretty slick. One of my best yet.

The devil went down to Georgia | Peter Verdone Designs










I'll be healing up and addressing the failure. Moving forward, my bikes will be even better, after finding where the limit lay.


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## Drew Diller (Jan 4, 2010)

Gnarly. I've had that same injury. Lived with it undiagnosed with two years before having laproscopic cleanup and patch work. The nerve uh, "crackling" will subside in time, if you end up getting that sensation early on.

If I'm comprehending this, the wheel failed first and the handlebar got thrown against something immovable, snapping it sharply?


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## .WestCoastHucker. (Jan 14, 2004)

damn, that sucks!


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## Sparticus (Dec 28, 1999)

You employ SRAM drivetrains? Wouldn't have guessed.

Hope you heal quickly & completely.
=sParty


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## scottzg (Sep 27, 2006)

Drew Diller said:


> If I'm comprehending this, the wheel failed first and the handlebar got thrown against something immovable, snapping it sharply?


It's tough to say what happened, based on his recollection. The damage to the wheel is weird, and the photo with the bike on the trail doesn't show anything that should cause destruction.

I'm not remarkably skilled or athletic, but i'm a big guy and have strength to match. I'm running my first carbon bar after avoiding them out of fear. In the past i've regularly broken equipment while using it as intended. It's distressing to see this failure.

I saw pvd's writeup the same day i saw tomwalker92's pemberton train gap crash... still kinda reeling from what pushing the sport can lead to, from both the riding and the engineering perspective. Be safe out there.


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## dr.welby (Jan 6, 2004)

I used to break handlebars for a living.

We had one test machine that was just a pneumatic cylinder attached to the end of the bar. You'd slowly increase the pressure and measure the deflection of the bar until it bent.

For most aluminum bars, you could see where the bar was starting to yield, and the amount of deflection would increase as the bar went past its yield strength. Really thinwall racing bars would be a little more interesting since sometimes they would buckle and do weird things.

But the carbon bars - they only had two states: OK and Exploded. You might hear some crackling noises as you got close, but there was a fine band of load between order and chaos. The failures were always dramatic and LOUD. Most of the metal bars would just end up bent but rideable. The carbon bars were always completely destroyed.

This was 20+ years ago when the first production carbon bars were coming out so things could be different these days. But reading PVD's description about not having problems with the same design before makes me think that this bar just went that little bit further than his previous bars.


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## dblspeed (Jan 31, 2006)

Sorry to hear, hope you heal up fast PVD.

Hard to say, but IMO it seems difficult the bar would snap before the wheel with that kind of damage to the rim, with little weight on it, unless you crashed the rim with your weight, but what would be the chances\physics of such a thing and maybe you should have hit your top tube\stem first? I've personally had a carbon bar snap similarly after a crash without being on the bike, just by hitting a rock the right way.


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## ru-tang (May 20, 2009)

Wowza, not a fun day. I've broken the fruits of my labor which was of course on a solo mission, in the dark, in the winter and I was kayaking. Got out alright luckily, but it really makes you think about every detail of your designs.

Peter- Can you explain the high rise bar configuration in simple terms? I've read through some of your posts about the bike but I seemed to have missed it or not understood the explanation. Is it about creating the longest front end, while allowing for a functional bar height? If you just made a taller steerer tube (while maintaining the same wheelbase and head angle), you would be creating a longer stem length and shorter steering axis to match the same handlebar position? Or the opposite, if you had a taller head tube then matched the grip position with flat bar and a 15mm stem, it would push your wheelbase way past the target?

Lastly, do you think that switching to Ti for the bars would give you a similar dampening properties but not run the risk from carbon?


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## pvd (Jan 4, 2006)

ru-tang said:


> Can you explain the high rise bar configuration in simple terms?


The stem/bars are used to connect the hand grips to the fork in the correct position for use. The long front center and low height of the top of the headset means that this bar/stem has a very low offset from the axis and high height from the headset.

The riding position is similar to other bikes.

I'm soooo RAD! | Peter Verdone Designs


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## pvd (Jan 4, 2006)

ru-tang said:


> Lastly, do you think that switching to Ti for the bars would give you a similar dampening properties but not run the risk from carbon?


Titanium (and steel) are terrible materials for handlebars. They will not flex as much as needed and will take a set if they are really pushed hard. Carbon is a perfect material for high flex without taking a set. We are still trying to figure out what went wrong with this particular bar. None of the others have failed. I'm soliciting feedback from the composite experts in my circle. So far, everyone thinks the wheel and bar failure is very odd.


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## dr.welby (Jan 6, 2004)

pvd said:


> Carbon is a perfect material for high flex without taking a set.


"Taking a set" is a failure mode that usually keeps your bike controllable. Detonating into two pieces (and leaving a jagged end to impale yourself on) sounds like a less desirable situation to end up with.


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## ru-tang (May 20, 2009)

pvd said:


> The stem/bars are used to connect the hand grips to the fork in the correct position for use. The long front center and low height of the top of the headset means that this bar/stem has a very low offset from the axis and high height from the headset.
> 
> The riding position is similar to other bikes.
> 
> I'm soooo RAD! | Peter Verdone Designs


Thanks, I think thats what I was thinking but without the proper terminology, super cool work.

Heal up!


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## pvd (Jan 4, 2006)

dr.welby said:


> "Taking a set" is a failure mode that usually keeps your bike controllable. Detonating into two pieces (and leaving a jagged end to impale yourself on) sounds like a less desirable situation to end up with.


The failure I show is not representative of the design. There was a flaw in the material, application, or something about the wheel failing first that caused the catastrophic failure. Other examples haven't had issue.

I don't use steel or titanium in this design as the end product is terrible and fails. While it may not fail catastrophically, it's not considered viable for my needs.

With proper controls and engineering, carbon will be far safer and higher performing than metal substitutes. We just need to determine those controls and engineering to ensure that this doesnt happen again, preferably with even more flex.


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## dr.welby (Jan 6, 2004)

pvd said:


> The failure I show is not representative of the design


Is it a 50% failure rate or 33%?


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## Drew Diller (Jan 4, 2010)

pvd said:


> With proper controls and engineering, carbon will be far safer and higher performing than metal substitutes. We just need to determine those controls and engineering to ensure that this doesnt happen again, preferably with even more flex.


This is the basis of why I started my company and received shock after shock, which motivated (demotivated?) me into delaying shipping any product until I was sure WHY handlebars were breaking. Doing so cost me... yeah... about $10,000, over the years, in slow costs. The way I figure, it's better me spending it than someone else while breaking (a) bone(s) and also suing me.

The failure looks like the bars I had that lacked significant hoop (circumference oriented) windings. The best bars I've made fail on the underside of the bend, they sort of crush, but don't shear off, leaving the top side intact. That said... even those bars could explode when overloaded beyond what a human wrist could transfer.

That's why I'm wondering if your bar isn't the culprit. I'm guessing it was given an acute situation that it just couldn't do.

I'm wondering if even the wheel is the culprit at all. Like did you just hit something nasty. Or are you shredding just too dang hard for a rigid bike?

I don't consider myself an expert yet but yeah I'll toss my hat into the "that's weird" category.

Also, I figured out where exactly pvd is on my irk-o-meter. Don't think we're too fond of each other but when I heard you broke I bone I genuinely felt bad / sad.


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## pvd (Jan 4, 2006)

10%.
Is your point that R&D is not useful and we should just do things as they were done 50 years ago?


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## dr.welby (Jan 6, 2004)

pvd said:


> 10%.
> Is your point that R&D is not useful and we should just do things as they were done 50 years ago?


As I mentioned above I literally did R&D on handlebars.

My point is more this: do you have sufficient failure data to where it's worth the risk of using your body as your test rig?


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## pvd (Jan 4, 2006)

Being in the game is the most important thing. Working out the details follows.


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## VegasSingleSpeed (May 5, 2005)

scottzg said:


> It's tough to say what happened, based on his recollection. The damage to the wheel is weird, and the photo with the bike on the trail doesn't show anything that should cause destruction.


Armchair analysis:

Bar failed first. PVD's weight/force onto the intact side of the bar (left side) forced the fork/wheel to turn hard right. With the tire/rim turned nearly perpendicular to the direction of travel, the resulting shear force buckled the rim. Don't focus on the crease in the rim, look at the rightwards deflection of the rim; the crease probably occurred near the peak of the rim's lateral deflection, as the spokes on the right side completely unloaded (I wouldn't be surprised if you find a number of spokes on the left side of the wheel are elongated).

Interesting side note, about 20 years ago, I was t-boned by a car at an intersection. An 8" segment of the rim busted cleanly from the rest of the wheel -the section where the wheel was in contact with the ground when I was hit. This was a tubular tire/rim, and there were no abrasions/marks on the rim to suggest that the tire compressed and the rim contacted the ground, nor did this occur near the rim's seam. The coefficient of friction of the tire to the ground, and the adhesion of the tubular glue, and -importantly- the very small period of time over which the lateral forces from the impact acted through the bike and to the wheel, was sufficient to rip 8" of the rim away.

Heal up, make it better!


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## dr.welby (Jan 6, 2004)

Drew Diller said:


> The failure looks like the bars I had that lacked significant hoop (circumference oriented) windings.


The more I think about the more I suspect this diagnosis is correct. This would explain the bar failing a short distance from the steel base, and the sudden (nonlinear/unstable) failure mode.


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## Little_twin (Feb 23, 2016)

The wheel damage is the real “wrench in the spokes” here. It’s a very odd failure alone, looking at the other damage doesn’t help clarify it. 

I know the spot this happened very well, PVD’s pictures don’t do it justice. The g out is very sudden, a slight miscalculation makes it a very abrupt transition. Knowing the location, the wheel still is quite confusing. 


Sent from my iPhone using Tapatalk


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## Drew Diller (Jan 4, 2010)

So how's the shoulder? The titanium and goretex in my clavicle do that weird buzzing feeling a bit when thinking about this thread.


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## pvd (Jan 4, 2006)

The clavicle has been bolted together. Healing is taking place. Hope to be cutting some tooling next week sometime.

I have a new wheel. WTB built it up for me. They're local so they came by my house and we discussed the failures and the wheel. New rim is a KOM tough i45. A little wider than the Scraper i40 that had been there but also with two internal support ribs. I may be pushing the wheels a little harder than most of the plus crowd does with enduro style riding and a rigid fork.

I've been discussing the failure of the bar with a lot of professional folk. The carbon issue in particular has been discussed with a lot of fancy folk. I put off talking with my supplier about the issue until I really knew what I was talking about and what it could have been. After a week and a half, I sent them an email. I was really stoked that when I did reach out to them in the email, their engineers got back to me within the hour and have done a lot to help me sort out solutions. No CYA bull$hit. Per our lengthy conversation, I'm going to move to similarly dimensioned tube but with a different layup schedule and pre-preg rather than filament wound. This should add a lot more strength with just a little more stiffness and more consistency in the composition.

The overwhelming consensus among all the folk that I talked to was that I was pretty good with the engineering but I got unlucky without enough unnecessary material to make sure. A little more margin of error to cover my bases should make the difference.

Hopefully this all works out and in in time, move to a custom layup that has the flex I want with the strength I need.


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## compositepro (Jun 21, 2007)

pvd said:


> The clavicle has been bolted together. Healing is taking place. Hope to be cutting some tooling next week sometime.
> 
> I have a new wheel. WTB built it up for me. They're local so they came by my house and we discussed the failures and the wheel. New rim is a KOM tough i45. A little wider than the Scraper i40 that had been there but also with two internal support ribs. I may be pushing the wheels a little harder than most of the plus crowd does with enduro style riding and a rigid fork.
> 
> ...


Odd the fancy folks link takes you to a flamingo hat


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## Drew Diller (Jan 4, 2010)

dr.welby said:


> The more I think about the more I suspect this diagnosis is correct. This would explain the bar failing a short distance from the steel base, and the sudden (nonlinear/unstable) failure mode.


So, pvd and dr.welby, some thoughts.

I recently made a handlebar for a client who wanted to have a lot of bags attached to either side of the stem clamp area of a handlebar. Light-but-loaded backcountry off road type. Specifically the 31.8mm clamp diameter area needed to extend the equivalent of 4 inches in length, so 50.8mm per side away from center. And a desire to be comfortable and bendy. 800mm total width, so, a lot of leverage.

I decided to do an ultra low cost approach: a single OD tubing diameter of 22.2mm, with the requested sweep angles, constructed in half tubes (lengthwise), then bonded together in a center sleeve.

Much like pvd's design here.

It didn't pass testing. My quick test before bothering to put a bar into my gravity sled is to just stand on the bar in a little stem fixture, test it with my body weight (180lb), then progress to hopping up and down with my ankles, then hopping up and down with my knees. The only bars to make it past this test are various Salsa bars, Renthal bars, Race Face bars, and some of my own design that had the 31.8mm to 22.2mm tapered monocoque that is common among the aforementioned bars.

The Ebay bars snap like twigs when doing this.

ANYWAY, the non-tapered tubes that I recently made fractured under compression. They were _almost_ strong enough. They did not completely shear off, because I made the laminate stack quite thick at 3mm. They fractured at the exact same location as pvd's glue-in bars: a short distance from the sleeve.

Had myself a long chat with my materials science mentor and he confirmed this will happen time and again. It's the highest point of leverage without being immediately reinforced by the sleeve, yet it lacks the ability to deform its circular shape into a semi oval. CRUNCH. The fix is to reinforce the area and reduce the wall thickness on the way toward the hand grip section.

I haven't yet done the fix. Instead I went back to a monocoque construction. I've been trying to think about the problem intuitively - one should build a triangle to spread that compression around, but one is limited by the OD of the hand grip area.

Anyway. It happened to me too. On a fixture, at least. I'll snap a pic later and upload after I'm back in from the shop


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## Drew Diller (Jan 4, 2010)

Pics attached as I said I would in previous post.


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## Darth Lefty (Sep 29, 2014)

Drew Diller said:


> The fix is to reinforce the area and reduce the wall thickness on the way toward the hand grip section.
> 
> ...one is limited by the OD of the hand grip area.


This is maybe not the fix you want, but you could look into Y-joints in fuel tanks on rockets for an idea. The tanks are often under quite high pressure (especially solid rocket motors) and they distend a lot. The skirt (the flange that attaches to the interstage) must pass not just thrust but a huge bending load especially in something like an air-to-air missile. So that joint is pretty crucial. The Y-joint is welded in metal tanks. But in composites it's wound on after the pressure vessel or wound separately and bonded on, and it contains a less-rigid filler to spread the load around. You could make an analogy to pointed bike lugs but it supports a diameter change and is axisymmetric.


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## Little_twin (Feb 23, 2016)

@pvd what ever came of this? Rider error? Bad luck? Bad design? More importantly, what have you done to ensure your fork doesn't suffer the same fate? Some riding instruction? Different carbon tubes? Did you do a bunch of good between then and now and you're relying on karma? The people want to know!

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## pvd (Jan 4, 2006)

I went on a deep dive into this after the incident.

1. We don't know what happened first, wheel failure or bar failure. Everybody has an opinion but considering just how catastrophic each was and there hadn't been another case seen of either, it's just a guess. The shame here is that nobody saw it and there was no video.

2. I talked with a ton of engineers and did some of my own testing in the lab. At the end of the day, I decided that the filament wound tubing that I was using opened too much possibility for nucleation of failure. I ordered new tube that was a roll wrapped pre-preg of a specific type of carbon. I went back and replaced the tubing in all of the bars that I had done until then with the new material to ensure most safety. I lost some flex with this swap. One day, I'll have custom bar parts made for me that will be very strong and flexible.









New carbon | Peter Verdone Designs






www.peterverdone.com





3. The fork tubes on the Supermarine Spitfire were kept as they were. They were filament wound but as they are so much thicker than the handlebars, there is less of an issue with one tiny error producing such a problem. It could happen, it's just so much less likely. FWIW, the Spitfire was ridden 2-3 times a week throughout COVID. It's been one of my most favorite bikes. I also ride it as hard as I can, like an enduro bike, so it's pushing the fork to the limit.









Super Ultra | Peter Verdone Designs






www.peterverdone.com





4. My most recent bike, the TIE Advanced X1 uses both bar and fork tubing in pre-preg roll wrapped tube. I've been testing the bike very very hard. Even as I increased the amount of exposed carbon, the performance has been great.









2021 TIE Advanced X1 All-Road | Peter Verdone Designs






www.peterverdone.com












New Possibilities with Additive Construction | Peter Verdone Designs






www.peterverdone.com












The end of the all-road. | Peter Verdone Designs






www.peterverdone.com


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## Little_twin (Feb 23, 2016)

Thank you for the follow up. Very detailed. 

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## compositepro (Jun 21, 2007)

PMSL full of ****


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## pvd (Jan 4, 2006)

compositepro said:


> ****


Oh joy. The noob is back.


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## compositepro (Jun 21, 2007)

You mean the noob who calculated the stresses when your bar broke and not a single engineer would help you, peculiar how for such a talented guy you cannot do the most basic of engineering calculations but some fool is letting you talk about advanced engineering talk about the blind leading the blind,

i do however enjoy seeing what delusional **** you are spouting these days if nothing else it serves as an effective barometer of how the internet will listen to anyone if they spout enough


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## pvd (Jan 4, 2006)

*I mean the noob that pretends to be an engineer. If all you can do is copy the work of others, you're just a plagiarist.

You were one of the people I contacted when I was looking into my carbon problem as you pretend to be a specialist. You were not the only one. Because you were unable to offer anything constructive that would move toward a solution, I relied on my own calculations, tests, and discussions with other professionals.

Again, you aren't a real engineer. You're just a plagiarist copying the work of others with fancy tools. Worse, your alcoholism and anger issues continue to paint you into a very lonely corner that surely is it's own feedback loop.*


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## compositepro (Jun 21, 2007)

Lol and your still at it im not here to offer you anything in fact im still of the same opinion of you when you appeared on frame forum and got booted 20 years ago yep i told you then i though your a **** and still do ,the fact you couldnt figure out a basic strength calc stress calc or any other speaks volumes what you did was ask your mates lol the fact if anyone had asked you to do a basic calc and you cant also is pretty damning

see engineers dont just do pretty solidworks pictures backed up by their own parameters and own opinions they get given problems and have to go to first principles first principles to you is looking at what got done on the www asking how pretending you own it and then doing a write up to the rest of us. Oh and i have a piece of paper from a university that has been validated by some pretty advanced engineering companies as relevant to my role day to day , you attend for 6 years and sit some exams they might give you one tof course their validation is far more important than some media love in on the www

we go to the figures first you ended up on your ass because you couldnt do the basics andasked questions after the plane crash , thank **** you dont get asked to do anything where a life is dependant on it

Grifter is a great word you can use it instead of technician in the future

alcoholism is where someone has a drink problem, again facts (i dont drink) mean you have assumed like when you assumed i was making tools ( havent for 5 years) you keep going over old ground poppet and regardless lots of people thought they were great and they were cheap and got people into the game theres only you complaining lol


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## pvd (Jan 4, 2006)

compositepro said:


> im not here to offer you anything


It seems you never have anything to offer. 
I'm a smart enough guy to seek out experts in materials and processes when I need them. In our discussion, you proved that you really lacked the ability to do much of anything without a bunch of fancy software and 100% information. That's not very useful outside of your own little corner of the office. I spoke to about 4 other composite experts that were able to contribute so much more than you could. I listened to them.
Also, you don't know what calculations were done....and that's the problem, you don't know what calculations were done.


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## compositepro (Jun 21, 2007)

LOL No i said without the actual layup you had been given i would be guessing , did you tell any of the other composites experts you didn't have a clue what was in there too? because its the first thing they would have asked , no one bakes a cake then guesses what ingredients are used , (edit I just read through the conversation and nowhere did I state I needed any fancy software this is a figment of you're imagination) however it does read more like you were trying to garner information to try and hang Rockwest out to dry that is clear from the conversation text and tone and on top of that the fact you stated every other composite expert knew very little...lol but still more than you.



Unfortunately moschops i do this for a living and my corner of the office is inside a place that relies on the fact people have a fucking clue before they even vet them to do the job so no Im giving you nothing for free but have done so for plenty of other people over the years who will probable disagree with you , rest assured youre broke ass we learned long ago cant afford to do much but bad mouth people on the internet

The rest of what you wrote is laughable at the very best and a poor attempt to explain the fact you were are a clueless div from first principles the only thing it probably serves to others is how not to do something , YOU DERIDE OTHERS FOR ASKING ABOUT SIZES WALL THICKNESS ETC AND HAVE DONE THE SAME THING YOURSELF that's the part that's actually really fucking funny remember that when you are chiding them for asking dumb questions.

Im pretty sure if this had happened in the real world and not your imagination ,you would have tried to write it up chapter and verse name dropping all you could to save your very thin skin what happened was you went back to rockwest had to eat humble pie for picking both the wrong type of tube and wall thickness , gave them some loads that again you probably pulled from someone else and they said here try this.

you are full of **** mate as ive said before , but what i do know is you didnt do any math ( and its mathematics by the way) personally, im sure you will be seething a bit more that your fragile ego is yet again taking a battering so will wait for the next PVD attack ( will it be your a nothing a nobody or will it be some other weird assumption ,these retorts follow a familiar pattern) maybe head off to one of your secret backroom facebook groups , you know the one where you and your mates ***** about and slate others, you might find some cuddles and hugs and support.

i have to go and finish my macrame now or whatever hobby ive told the internet im doing this week

kisses


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## Cord (Dec 10, 2006)

pvd said:


> *Again, you aren't a real engineer. Worse, your alcoholism and anger issues continue to paint you into a very lonely corner.*


Now this is entertainment, i was going to say "pass the popcorn" but sod it, make mine a large double vodka or 5. And can i have it in one of those real fancy glass/carbon tumblers? But please dear lord don't let PVD have designed it, i HATE spilling my drink, and there is clearly only room for 1 drunk/angry "engineer" in this place.


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## Drew Diller (Jan 4, 2010)

Time for a bike ride guys, holy @#$*.

Thinking about this more, I guess I'd want to know the original laminate schedule (it was prefab, yes?). If it's one of those things where the laminate is like 0-45-90-0-45-90, I used to do that and was instructed that the laminate fights itself from the inside out. Needs to be a smooth transition. Since the outer layers move more relative to the inner layers, the inner layers can be oriented axis on load, the outer layers off axis. If it's a pattern that repeats rather than transitions, it's kinda like the inner layers don't get loaded much until after the outer layers have already failed. I'd also want to know _specifically_ what resin system was used. I've seen resin systems differ *by a factor of three* for compressive strength values, and in my own low tech testing, every.single.failure was in compression (which sometimes does not look like compression if the breakage is total severance). It took me two years to realize the AdTech 820 resin I was using just simply... lacked... the compression strength I needed, where the needed compression strength could be found in prepregs. I found myself staring at a pair of spec sheets one night thinking "How did I miss this?" Most of the values were similar except for compression and the prepreg beat the snot out of the rest in that regard.

If I had to guess, prefab tubes are not really engineered toward a specific purpose other than "they're light", and the strength-to-weight-to-flex demands of the bike industry have pushed waaaaaaaaay beyond that prefab envelope.

For anyone reading this thread years in the future after it was initially posted, and you're like, Hmm should I build my own carbon stuff? Don't, *unless* you want to scratch your head, and then scratch your head some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and then some more, and get yourself some liability insurance.


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## Little_twin (Feb 23, 2016)




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