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Old 05-14-09, 03:26 PM   #1
kaitanium
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what are the chances of frame snapping...

so for you trail riders out there what are the chances of a frame snapping where the steerer inserts into the frame? like this:
http://www.youtube.com/watch?v=6UmaZ...layer_embedded

ive seen way too many videos of this stuff. but its not like i hop rocks or anything. tons of vids like this!
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Old 05-14-09, 03:38 PM   #2
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Old 05-14-09, 03:49 PM   #3
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There are an enormous amount of variables, but....

If you "case" a jump by landing wrong, like the rider in the video, while riding a frame never designed to survive that type of landing, failure of the frame is almost guaranteed.

The junction of the downtube and head tube is the most likely failure point on a bicycle frame.
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Old 05-14-09, 04:00 PM   #4
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There are an enormous amount of variables, but....

If you "case" a jump by landing wrong, like the rider in the video, while riding a frame never designed to survive that type of landing, failure of the frame is almost guaranteed.

The junction of the downtube and head tube is the most likely failure point on a bicycle frame.
I would say that your first statement is correct and the last two statements are false.
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Old 05-14-09, 04:14 PM   #5
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I would say that your first statement is correct and the last two statements are false.
and your defense would be...?
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Old 05-14-09, 04:14 PM   #6
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I would say that your first statement is correct and the last two statements are false.
Based on what?

Why is the most likely location for a gusset on an MTB frame placed between the head tube and downtube?

Because...

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Old 05-14-09, 05:06 PM   #7
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and your defense would be...?
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Based on what?

Why is the most likely location for a gusset on an MTB frame placed between the head tube and downtube?

Because...

Let's examine the original statement: "The junction of the downtube and head tube is the most likely failure point on a bicycle frame." It is not any more because of what you just said in your follow-up: that this is the spot that frame makers gusset and reinforce the most robustly. So, yes, it is one of the most highly-stressed points on a bicycle frame but product-liability precautions in that area mean that a frame will most likely fail more toward the middle of the downtube or top tube or anywhere a suspension mount (in the case of FS) has been welded on.

On a more technical note, the picture you supply shows a frame that did not fail at the juncture - -it failed in the manipulated tube behind it.

Now, backing up to your second statement: ". . . while riding a frame never designed to survive that type of landing, failure of the frame is almost guaranteed." I say that is false because this is a totally unqualified statement. If I case ONE landing like that on an X-mart bike, I'm almost guaranteed that it will fail catastrophically? Not that, maybe, over time of such abuse, that it is likely that the frame could be weakened to the point of eventual failure?

I'm nit-picking you for a reason. People come on here all the time and make ill- or half-informed blanket statements like that and I just decided I'm tired of seeing this stuff get thrown out here unchallenged. You might think I'm splitting hairs but I'm just making a case for a little accuracy.

BTW, your first stement was true: "There are an enormous amount of variables . . ." There are. That's why it's wise to not make sweeping statements that don't hold up.
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Old 05-14-09, 06:03 PM   #8
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On a more technical note, the picture you supply shows a frame that did not fail at the juncture - -it failed in the manipulated tube behind it.
The pictured frame failed at the down/head tube junction in the HAZ (Heat Affected Zone) of the weld. It's the weakest point of any welded aluminum joint.

The cause: Rider error.

MTB frames are not indestructable unless they're built to withstand the abuse of dirt jumping or "slope style". Landing 50/50 (one wheel on the landing slope, one wheel off) will cause a frame to fail. As the OP mentioned, this type of failure is well documented.

Want your frame to last "forever", (or nearly forever)? Don't crash.
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Old 05-14-09, 06:10 PM   #9
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The reason you see so many videos like that is that most x-mart bikes have that little decal that reads "NOT FOR OFF ROAD USE". They're just not built for it.
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Old 05-14-09, 06:17 PM   #10
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interesting info here! well uh hopefully the rocky trails i go on wont be too much of a prob for my '02 hardrock....

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Old 05-14-09, 06:18 PM   #11
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Here's a very famous headtube failure vid... ouch!

http://www.youtube.com/watch?v=JLRDRzMWIsg
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Old 05-14-09, 06:21 PM   #12
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If you "case" a jump by landing wrong, like the rider in the video, while riding a frame never designed to survive that type of landing, failure of the frame is almost guaranteed.
I've cased so many DJs its not even funny. And my XC frame still hasnt broken.
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Old 05-14-09, 06:23 PM   #13
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Here's a very famous headtube failure vid... ouch!

http://www.youtube.com/watch?v=JLRDRzMWIsg

yea i saw that one...and that wasnt even junmping rocks and such!!! just broke...i wonder how long he has used that bike and how much abuse it has gone through
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Old 05-14-09, 08:53 PM   #14
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so for you trail riders out there what are the chances of a frame snapping where the steerer inserts into the frame? like this:
http://www.youtube.com/watch?v=6UmaZ...layer_embedded

ive seen way too many videos of this stuff. but its not like i hop rocks or anything. tons of vids like this!
If you case it like he did, about 1 in 3.
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Old 05-14-09, 09:39 PM   #15
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HAHAHAHA!!!!Thanks for the vid. Finding all those fail videos were hilarious!!!!
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Old 05-14-09, 11:55 PM   #16
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yea i saw that one...and that wasnt even junmping rocks and such!!! just broke...i wonder how long he has used that bike and how much abuse it has gone through
This is why I am not a fan of dark colored frames (although I still have one, black ). Right now have a silver, two butter-yellow bikes, and one clear-coated bike (natural aluminum finish).

A light colored frame will give plenty of visual warning if a crack appears, but it's difficult to catch those on dark colored frames. Having said that, I suppose it is possible to ride a bike to breaking-point without premature cracks showing...

Over the years I've seen cracks appear in various places but the most common place I've seen them is near the welds at the bottom of the headtube/downtube connection or somewhere along it's gusset if it has one. It pays to occasionally inspect that area, especially after a crash (or if the bike crashes regularly ).

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Old 05-15-09, 09:06 AM   #17
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It pays to occasionally inspect that area, especially after a crash (or if the bike crashes regularly ).
+1. That's why a thorough cleaning of every part of the bike on a regular basis is a sound idea. It will give you a chance to spot any defects.
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Old 05-15-09, 11:26 AM   #18
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mmm yes. inspection and cleaning! sometimes i dont want to clean my bike though...i love all that grime and dirt and mudsplash marks on it...
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Old 05-15-09, 12:03 PM   #19
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mmm yes. inspection and cleaning! sometimes i dont want to clean my bike though...i love all that grime and dirt and mudsplash marks on it...
Some folks think that dirt on the bike is a badge of legitimacy.

Yeah, a lot of times I'm just too lazy to clean the silly thing.
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Old 05-15-09, 12:44 PM   #20
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Some folks think that dirt on the bike is a badge of legitimacy.
hehe i do think that way sometimes but well i have nothing to hide. its not like my bike is a crazy XC or anything and im just posing like i know what im doing haha. im sure some buy some crazy looking bike, only to bike through rain puddles

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Old 05-15-09, 01:22 PM   #21
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People come on here all the time and make ill- or half-informed blanket statements...
This seems like a blanket statement to me...I'm a typical person...all that I say is from the utmost + dedicated + research from credible sources



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I just decided I'm tired of seeing this stuff get thrown out here unchallenged.
I'm a little sick of getting called out on my uninformed blanket statements. I thought that when I became deputy...I could do whatevah I dang well pleased.




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I'm just making a case for a little accuracy.
I'm just making a case for a little neener, neener

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Old 05-15-09, 01:50 PM   #22
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I still remember this quote from Michael on The Office:

"Wikipedia is the best thing ever. Anyone in the world can write anything they want about any subject. So you know you are getting the best possible information."
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Old 05-15-09, 02:22 PM   #23
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Old 05-16-09, 08:59 PM   #24
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http://www.youtube.com/watch?v=8ZNW2lWokU0
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Old 05-16-09, 09:00 PM   #25
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