Bicycle Mechanics - Bent Aluminum Dropout
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06-18-12, 12:13 PM
Do you think this would be able to be bent back?
I know bending aluminum causes it to loose structural integrity, but I was thinking that weight isn't really put on the bottom part of the dropout. But I'd like to hear you guy's oppinion on it.
06-18-12, 12:22 PM
Wow, how the heck did that happen?
Well I think that the dropout will break when it is bent back. Aluminum can only take a certain amount of bending before it snaps. That looks like a LOT of bending done. I imagine that part of the dropout is heavily fatigued at this point.
If it was steel, I wouldn't worry too much but aluminum? Not to sure that would be safe.
06-18-12, 12:32 PM
Well, it's not exactly useable in that condition, so I guess there's not a lot to be lost by trying... unless you're concerned about it failing at a later time if straightened? A guy I know once tweaked a moderately bent hanger back in line with large adjustable wrench, and it's been fine ever since. That said it wasn't nearly as bent as yours... If you're gonna try, I would try and get it right first time around though :p
06-18-12, 12:35 PM
Well someone is giving away his s-works cx frame for free in my town with that bent dropout. Just seeing if it was worth trying to fix.
It was free for a reason ;P
06-18-12, 12:35 PM
I think even bending a steel dropout that much will already have caused brittle fracture. You can see it already in the necking down near the mid-way of the radius where there's a kink in the metal. The inside of that radius is probably already loaded with lots of small fractures.
What happened to the bike? Did someone hook the rear wheel and frame between two vehicles and then draw/quarter the bike? Looks like the rear axle was pulled by force out of the dropouts.
06-18-12, 05:52 PM
"wow" was my first thought too.
If it bends back without snapping, then a little careful tig welding could strengthen it....
06-19-12, 05:56 AM
06-19-12, 05:57 AM
Bent?! What do you mean "bent". That thing is totally unusable. The dropout is broken, yes broken not bent. There is not enough clamping space for the rear wheel.
06-19-12, 07:55 AM
Is that the right dropout ? (I initially thought it was the left). Where's the hanger ?
IMO there's no way you'll straighten it cold without it failing. Aluminum has some ductility so I'm not shocked it bent that far without cracking, but aluminum doesn't respond well to repeated bending. It might be salvageable if heated and straightened, but this is a skill task, because the temperature range between where aluminum becomes a bit plastic, and where it melts entirely is very narrow.
The other option is to fabricate a replacement and weld it to what's left of the dropout. This will not be easy because there's so little left to work with, but it is possible.
If the frame isn't valuable, it's probably toast, but before trashing it, I'd look for someone skilled in working with aluminum, possibly in the high end motorcycle or automotive world, and let him try to straighten it. I'd also consider getting 2 washers, sawing and filing them to form dropout shapes, belt sanding them dead flat and bonding them to the face of the repaired dropout for added strength.
In fact, if you can make a nice pair of faces, you might have someone weld in more material to the dropout without bending it, clean it up with a file, and bonding on the steel faces. Other than the actual welding, this is something you can do yourself, so the cost is low, and there's less risk to totaling the frame by breaking off what little you have left of the dropout.
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