[pvd]

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.

 

[Drew Diller]

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?

 

[.WestCoastHucker.]

damn, that sucks!

 

[Sparticus]

You employ SRAM drivetrains? Wouldn't have guessed.

Hope you heal quickly & completely.
=sParty

 

[scottzg]

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.

 

[dr.welby]

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.

 

[dblspeed]

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.

 

[ru-tang]

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?

 

[pvd]

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

 

[pvd]

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.

 

[dr.welby]

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.

 

[ru-tang]

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!

 

[pvd]

"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.

 

[dr.welby]

The failure I show is not representative of the design

Is it a 50% failure rate or 33%?

 

[Drew Diller]

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.

 

[pvd]

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

 

[dr.welby]

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?

 

[pvd]

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

 

[VegasSingleSpeed]

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!

 

[dr.welby]

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.