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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.


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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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Discussion Starter #23
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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would rather be ruined
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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.

Odd the fancy folks link takes you to a flamingo hat
 

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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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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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