Bernard Kerr’s prototype frame snapped. I’ve busted wheels and hubs but have never snapped a frame like this. I wonder if it broke at the lugs that Pivots Prototype and Atherton bikes are running.
HUKIT
There is a video somewhere in pinkbike comments where you can see the carbon tubes pulling out of the lugs during the crash and image of the same somewhere in comments there as well
The two brands have quite different designs. Atherton downtube is straight, the Pivot is curved into the lug.
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Awful crash. A thing of absolute nightmares. i watched the BK LSD all week and was pulling for the guy. I was speechless when the crash happened.
I assume that's the same bike he was riding Hardline on. Wouldn't read too much into it in terms of the breakage. Hope he's feeling ok!
It’s really surprising to see this video showing Bernard Kerr’s prototype frame snapping, especially considering the robustness we’ve come to expect from modern mountain bike designs. Snapping a frame is quite rare. It will be interesting to see how Pivot and Atherton address this issue in their future prototypes.
What's old is new again....that makes at least three mfgs with recent models that are going back to the future with alloy-lugged carbon-tubed frames. It's a proven-ish design, but unfortunately you are putting three material failure properties into one frame...the thinnest being an adhesive layer. Putting them under these peak load stresses is fairly new though. I'm trying to figure out why companies are going back to this design, and of course it is immediately obvious - it's cheaper. Printing lugs and connecting them with carbon costs a whole lot less that numerous mold designs and human layup. I have no doubt it will be sold as the greatest thing ever and better than everything else though.
If they are going to continue with this construction type, they need to figure out a way to incorporate mechanical interference at the joint fitting as redundancy to adhesive. That's a tall order though and they may as well go back to full carbon molds at that point.
If they are going to continue with this construction type, they need to figure out a way to incorporate mechanical interference at the joint fitting as redundancy to adhesive. That's a tall order though and they may as well go back to full carbon molds at that point.
Looking at ATHERTON vs PIVOT photos, looks like the cable ports are in different locations. The Pivot has a lot less adhesive area on the down tube and Lub interface. I'm not a mechanic engineer, but I've glued a lot things in my life, maximizing adhesive area it always beneficial for longevity.
Somehow the engineers will find out a way to blame Kerr. I mean, has an engineer actually ever been wrong?
What do you do with the rest of the teams bikes now? Pretty big confidence shake...
Parallel tubes are easier to pull out than tubes at an angle no doubt, always thought these pivot prototypes looked suspect, those are poorly designed lugs for fewer operations in the mill.
Raw aluminum on carbon is a big no no too, insta corrosion = de bond
Then you ship it around the world and beat the snot out of it without the "engineers" eyes on it. Pretty negligent prototyping.
Parallel tubes are easier to pull out than tubes at an angle no doubt, always thought these pivot prototypes looked suspect, those are poorly designed lugs for fewer operations in the mill.
Raw aluminum on carbon is a big no no too, insta corrosion = de bond
Then you ship it around the world and beat the snot out of it without the "engineers" eyes on it. Pretty negligent prototyping.
I broke a bonded Raleigh frame in 88. Never again although I'd thought the adhesive would be better these days.
Race bikes ride the knife edge of weight to strength ratio. It happens, and it used to happen, and it will probably continue to happen. If you want to win you have to balance on the edge.
That said I recall the era of the thermoplastic frames (GT, mantis, etc) and how they failed due to the inability of the lugs and tubes to bond correctly. But also vitus bikes were able to make tiny aluminum tubes stick to aluminum lugs with small amounts of overlap and they would last for way too long, until the Aluminum was way past its prime.
That said I recall the era of the thermoplastic frames (GT, mantis, etc) and how they failed due to the inability of the lugs and tubes to bond correctly. But also vitus bikes were able to make tiny aluminum tubes stick to aluminum lugs with small amounts of overlap and they would last for way too long, until the Aluminum was way past its prime.
Here's a side view of the triple where the frame broke. What frame materials are you trusting to mega-case that gap?
One major difference between Pivot and Atherton is the lug to tube interface. Pivot is a single wall connection and Atherton is a double wall connection. Double wall allows twice as much surface area for bonding.
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