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  1. #1
    Lover of Old Chrome Moly Myosmith's Avatar
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    Shallow gouge in aluminum handlebar

    I have an aluminum flat handlebar with a slight sweep on my touring bike. It has a shallow gouge/scratch about 1/2 way around the bar right at the union between the bar and the left side of the stem. The bar is 6061T6 heat treated aluminum and fairly thin compared to the no-name aluminum bar on my beater bike. The gouge/scratch appears to have come from someone rotating the bar in the clamp without sufficiently loosening the clamp first and is deep enough to easily feel when running the tip of my fingernail across it. I have about 500 miles on this bike with the bar in that condition and have hit potholes and other assorted road hazards and the damage has not changed and it doesn't look like there is a crack. I've also put a lot of pressure on the bar in several directions to see if there was any flex or change and there was not.

    My question is, should the bar be replaced? It appears structurally sound now, but what are the chances of a gouge/scratch like this becoming a crack or causing catastrophic failure?
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  2. #2
    Certified Bike Brat Burton's Avatar
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    Without a brand and model to check the specs against, I'm guessing. And I'm guessing that if that bar is 6061 T6 then its also butted tubing and thickest on the area you're concerned about. Inless you're a rider that really stresses their bars, I'd say ride it.

    On the other hand, if worrying about it keeps you up at night, flat bars have to be one of the least expensive components to replace.

  3. #3
    Lover of Old Chrome Moly Myosmith's Avatar
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    Thanks for the answer. Unfortunately, there is no brand or model number visible. I'm sure it is butted tubing as it is very thin at the ends. I have been riding it and not losing any sleep but was wondering if heat treated aluminum was more likely to crack along a gouge like this. The bike is a touring/hybrid used 90+% on paved roads with the remainder being well packed gravel or dirt roads. The only hard use is on the occassional hill climb or when I can't avoid a pothole or other hazard.
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  4. #4
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    I respectfully disagree with the use it post. heat-treated 6061 in more vulnerable to notch stress, or local stress concentrations. If the score were longitudinal or farther from the stem, I'd also say it doesn't matter.

    But you have the triple whammy, heat treat, circular score, location at the highest stress point. One or two out of three you can wait and see, but IMO 3 for 3 says trash it.
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  5. #5
    Lover of Old Chrome Moly Myosmith's Avatar
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    OK, that's what I was afraid of. I wasn't too worried about daily use but I was concerned about those rare times when I might have to take a pothole or road hazard hard or to try to bunnyhop them. It's hard enough to save a near crash without your handlebar failing.
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  6. #6
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    Quote Originally Posted by Myosmith View Post
    OK, that's what I was afraid of. I wasn't too worried about daily use but I was concerned about those rare times when I might have to take a pothole or road hazard hard or to try to bunnyhop them. It's hard enough to save a near crash without your handlebar failing.
    In my experience bars don't break from potholes or bumps. Those loads are fairly small, but they can work the stress riser setting up a future failure. Odds are the actual failure will happen on a sprint or hill climb when you pull and/or twist the bar pretty heavily.
    Last edited by FBinNY; 02-20-12 at 09:12 PM.
    FB
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    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

  7. #7
    Certified Bike Brat Burton's Avatar
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    But I personally feel like this is all a shot in the dark. FB is perfectly correct on what he's saying, I'm maybe being overly optomistic about this 'gouge'.

    What was stated: " The gouge/scratch appears to have come from someone rotating the bar in the clamp without sufficiently loosening the clamp first and is deep enough to easily feel when running the tip of my fingernail across it".

    Just because it can be felt easily doesn't mean its deep enough to be serious. Just a scratch through the anodizing can be easily felt and that would be purely cosmetic. So would it be possible to post a picture or something?

  8. #8
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    I'm usually the guy that pooh poohs what I feel are excess safety concerns, so this is a bit of role reversal for me. I based my assessment mainly on the location and orientation of the gouge. Even a fairly shallow circular scratch here can create a stress riser in the place where bending stresses are highest. Then there the fact that the anodizing is gone, leaving bare metal where water will deposit salt, compounding the problem. Had this been further away, say 2" or so, I'd probably have said wait and watch..

    The other consideration I used is my "likelihood/consequences" method of looking at risk. For risks with mild consequences like nipple stress cracks on rims I tolerate high likelihoods for failure. OTOH, for steerers, stems, and handlebars where the consequences of a sudden failure are likely to be a serious injury, I'm not tolerant of risk at all.
    Last edited by FBinNY; 02-20-12 at 09:36 PM.
    FB
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    An ounce of diagnosis is worth a pound of cure.

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    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

  9. #9
    Lover of Old Chrome Moly Myosmith's Avatar
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    I tried getting a picture, but even on the macro setting the gouge/scratch doesn't look like much. Gouge might be overstating the situation, it is more of a deep scratch. The scratch is probably just through the anodizing. It doesn't look to have actually displaced metal, ie, no ridges on either side of the scratch. I'll run it past my LBS mechanic and see what he thinks.
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  10. #10
    Certified Bike Brat Burton's Avatar
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    Quote Originally Posted by FBinNY View Post
    I'm usually the guy that pooh poohs what I feel are excess safety concerns, so this is a bit of role reversal for me. I based my assessment mainly on the location and orientation of the gouge. Even a fairly shallow circular scratch here can create a stress riser in the place where bending stresses are highest. Then there the fact that the anodizing is gone, leaving bare metal where water will deposit salt, compounding the problem. Had this been further away, say 2" or so, I'd probably have said wait and watch..

    The other consideration I used is my "likelihood/consequences" method of looking at risk. For risks with mild consequences like nipple stress cracks on rims I tolerate high likelihoods for failure. OTOH, for steerers, stems, and handlebars where the consequences of a sudden failure are likely to be a serious injury, I'm not tolerant of risk at all.
    Agree with where you're coming from FB and I already stated that bars have to be one of the least expensive things to replace. But any concerns about salt corossion and in fact concerns about bar loading are really very dependent on the OP's driving habits.
    The hybrid I'm currently driving originally had similar black anodized handlebars on it and I had them polished simply because I like that finish better. Anodizing actually offers almost no protection from galvanic corossion anyway and I've simply waxed these and they're on their third winter. They still look perfect. The other question is how much the OP loads his bars while driving. Agreed its a touring rig, but some riders are still more agressive than others and if he drives like a *****cat, doesn't travel fully loaded, and its really just a surface scratch there's absolutely no risk.

    The decision to run it by the dealer is a good isea for a more realistic evaluation. Personally I do better with what I can actually see, its just that to me this is a tempered bar intended for off-road use and not just some city bike flat bar


    PS: I can't believe the system actually sensored *****cat! It doesn't even sensor political comments!
    Last edited by Burton; 02-21-12 at 06:31 AM.

  11. #11
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    Quote Originally Posted by Myosmith View Post
    Gouge might be overstating the situation, it is more of a deep scratch. The scratch is probably just through the anodizing. It doesn't look to have actually displaced metal, i
    That changes things, no deep gouge, means no significant stress riser, so vastly reduced risk of breakage. Touch up the scratch and heavily wax the area where the bar exits the stem, letting a small fillet build up at the junction with the stem. This is good practice anyway if you sweat or ride in the wet a lot, since it prevents salt from wicking in and building up at the edge of the stem. Then be attentive to new creaks or clicks that might come on down the road.
    FB
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    An ounce of diagnosis is worth a pound of cure.

    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

    “One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

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