Top tube gouge- Aluminum MTB
04-09-16, 11:03 PM
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Top tube gouge- Aluminum MTB
I've read lots of the aluminum wisdom about how any small ding or scratch can potentially kill your frame. I've got an 04 Gary Fisher HKEK hardtail that I use for a trail bike- I'm not doing anything terribly extreme on it, but I do weigh 200 lbs. I transported the bike across the country on a trailer, and had a piece of steel rubbing on the top tube that I didn't notice. It gouged out some of the top tube. I wanted to get a couple more opinions, but since the top tube is under compression, and the damage is in the center of the tube, I think I'll be OK to ride it. There's definitely an indent where the damage is, it's not just a paint scratch. I will take none of your comments as legally binding if you say it's ok and I crash and die or become horribly injured on it 
04-09-16, 11:59 PM
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Just an opinion but I think it would be fine. If it was a Crack or perhaps a sharp type of damage there would be cause for concern but the damage is not through the tube and is soft edged. Keep an eye on it for awhile and see if it gets any problems.
04-10-16, 05:44 AM
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Well, you're mainly worried about failure of the top tube under compression, i.e. buckling, in which the tube walls crumple and fold when a load is placed on the axis of the tube, compromising any compressive or bearing strength. But all metal is nice in that the crumpling and failure should be ductile, i.e. it should occur slowly and incrementally enough for you to notice and stop and dismount. (Structural engineers worry about this in comparison to concrete, which cracks and theoretically fails if not for rebar).
The only mode I'd really worry about is a massive shock that would crumple the tube *and* then fold the bike completely before you even notice any flex or crack. This seems hard to picture but I don't know if you go off 20 foot dropoffs as in a Red Bull video...
The only mode I'd really worry about is a massive shock that would crumple the tube *and* then fold the bike completely before you even notice any flex or crack. This seems hard to picture but I don't know if you go off 20 foot dropoffs as in a Red Bull video...
04-10-16, 06:58 AM
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Falcon3, Compared to my beater Cannondale, that's nothing. Regardless of frame material it's prudent to keep an eye on any damage.
You may consider a light sanding of the area to minimize any stress risers and a coat of paint, or even clear coat, to prevent corrosion.
Brad
You may consider a light sanding of the area to minimize any stress risers and a coat of paint, or even clear coat, to prevent corrosion.
Brad
04-10-16, 07:58 AM
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That frame is definitely a hazard, please arrange to sent it to me for proper disposal:-)
