Tuesday, July 1, 2008

Zipp B2 Handlebar Failure

Long story short, from the product's user : "I was out for my first road ride in awhile and as I was riding away from a stop sign I heard a mysterious crunch and my left hand became unweighted. I looked down to find my beloved Zipp B2 carbon bars fracture under my own power. This event was even more surprising because the bike has never even fallen over let alone been involved in a crash."

The fracture was to the left of the stem clamping plate. Someone did a high resolution blow up of the image and found a neat crack running at the bottom of the handlebar.

Is this why Zipp recommends running their own carbon stems with these bars? Or is it just another avenue to make more money. Both I would guess..(?)

Since he said the bike never took a fall, we might speculate that this is a clamp over tightening related issue? Its still scary. Imagine if this would happen at a race or while going downhill. Sheesh.

Photos courtesy of Weightweenies


Cycling Phun said...

Ron: Not an engineer, but I don't think I need to be to tell you that you NEED A TORQUE WRENCH when you start to bolt on carbon. I would go along with the fact that this was likely over-tightened. It even looks as though that crack is right at the edge of the clamping plate.

Anonymous said...

Don't know where these particular bars came from, but there have been counterfeit Zipp bars sold on eBay - here's the warning from the Zipp web site: http://www.zipp.com/Support/CounterfeitHandlebars/tabid/176/Default.aspx

carpetfiber101 said...

Over tightening sucks and happens.
Is there a fix other than buying a torque wrench? Perhaps there is a design change that would aid in carbon cracks?

I might suggest wider stem clamps with solid bolt plate faces. This will: 1- give more surface area to hold on to so bolts don't need to be tight in the first place and 2- Reduce the stress concentration at the clamp (where there are many forces already)

Donald said...

Yeah, get a good torque wrench but like Chris, for now I'm sticking with alloy.

ant1 said...

That sucks, but if it make you feel any better, I broke a titanium handlebar mountain biking. The left side snapped right off going over a 12 inch drop. I'm now a firm believer in the power of steel. At least it will bend before getting catastrophic.

Cycling Phun said...

Ron: Agree, I think you'd be more likely to try to really crank down two bolts over four due to tightness and slippage. I just think the pressure spread out from four would hold better.

Anonymous said...

I’m still a believer in carbon. The weight and comfort benefits, if the bar is installed properly, far outweigh the minimal disadvantages. Keep in mind that the forces that would cause the catastrophic failure of a carbon bar would definitely damage an alloy bar beyond safe use, not to mention that you’d be hitting the pavement/dirt anyway. Bicycles are much more technical now than they were 25 years ago and need to be treated as such. Every week I have home mechanics coming into my store with problems that arise from improper assembly... That they want warranty coverage for I might add.