Broken Handlebar

Quoted post said:

Originally Posted by Scott2468 [IMG]/img/forum/go_quote.gif[/IMG]

Has anyone experienced this?

Not yet. I'm glad you're OK.

I've got some 35 year old Cinelli and 3T bars that still get used, 26.4 and 26.0 mm, with no signs of weakening.

I don't think your torque on the faceplate had anything to do with this failure. You might consider a new 31.8 mm stem & bar, though. I have a hunch that the larger diameter bar and 4-bolt face plate might be a stronger junction..

Haven't had it happen to me, but there's a local forum that has a bunch of pics of broken bars posted. There are those who recommend regular replacement of Al bars, exactly b/c of this.

I too doubt you over-torqued. My guess is that when the bars were originally slid on they were accidentally scored (scratched deep) enough to cause a fracture point. If it failed right on the score line it may not be detectable. To add, alu does have a finite lifespan from a fatigue point, maybe time just caught up. I do know common folklore has retiring alu frames after bad wrecks, but then again a racing friend of mine has subjected his CAAD9 to about half a dozen horrific wrecks and it's still ticking. In fact he's managed more accidents in a single season than I've done in 6 years of racing. I'm just speculating - glad yer still ok but those nightmares can be a biatch.

Agree with previous comments. Just to add my two cents, if the stem has a sharp edge on it, when the bar is clamped it can create a stress riser or score mark on the bar which sets up an early fatigue failure with the bending loads of riding. Good stems should have "broken" edges, finished with a smooth radius.

Also, appears the stem bolt is corroded. Aluminum is subject to stress corrosion cracking, which can cause failure over time even if the bike isn't ridden. The stem puts a compression load on the tube, moisture tends to sit in the joint, so it's a natural place for corrosion to occur. If the bars have been installed since '03, that's certainly long enough to have this failure. Bikes left outside in the rain would be more susceptable of course. Washing often with high-ph (alkali) degreaser can set up this corrosion early.

You could checkout yourself by looking for white corrosion at or in the broken seam, or at the end of the stem. Also, you might take off the other side to look for a score mark or corrosion.

When you buy the new bars, get a new stem too. Don't look for the lightest-weight (thinnest) pieces out there, but rather the parts with the best machining and finish.

As mentioned check for sharp edges on the stem before mounting handlebars. Also w/ aluminum bars, you should carefully check the bars for corrosion when changing bar tape. For that reason, I'd change the bar tape at least once a year. Aluminum and salt water (er....sweat) are two parts of a wonderfully corrosive combination. Likewise, aluminum fasteners should be checked yearly (at least) for signs of corrosion.