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Discussion Starter · #1 ·
(forgive me if this doesn't make sense, for i've just had a few Sierra Nevada Bigfoot's to ease the day away...) does anyone else think that one particular part of the design on the rear swing arm on the new hecklers is kinda messed up....i was just looking at a thread about a cracked rear swing arm when i noticed this on the poster's bike....and rather than hijack his thread, i started a new one.....anyway, look at the distance from the down tube, vertically to the bottom of the "yoke" that joins the pivot to the rear swing arm itself (where both seat stays, and both chain stays come together...)...well that "C" shaped yoke on the new heckler is far bigger, and sits up higher than the previous generation heckler....if you look at this pic, vs. the pics of the cracked heckler, you'll see what i'm talking about....why is it that SC changed this feature???? it seems to me that a shorter, more stout yoke would be more effective, and less flexy....also, the yoke on the old heckler was a bit thicker than on the new one....i'm not sure if in the situation of the cracked swingarm, but in a situation like that, where you're not talking a big weight savings, why did they make the member thinner? very strange....



 

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looks like the newer yoke is a hydroformed piece, and the old heckler is cnc'd. i know hydroforming has come a long way in terms of strength, but i still like cnc'd parts.
 

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looks like they make it higher to clear the downtube at full compression:confused: but you're right, the part looks a little weak:eek:
 

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Discussion Starter · #7 ·
CHUNKY NUGGET said:
You do realize you are looking at 2 opposite sides in the pic? Yeh? The drive side sits up alot higher than the brake side.
Looks like the pics tricked ya?
no i'm not talking about the chain stays, but the yoke itself that the chain stays/seat stays attach to.....i thought about the clearance at full compression thing, but my heckler is running 5.7" of travel with a 2.25" stroke shock, and nothing contacts at full compression.....so why would they need to add clearance.....

sooner518 said:
better question, how is your Heckler so devoid of any scratches/dirt?! How do you get it looking so good?
i should have added that's not my heckler...it was the only photo i could find that had an angle of what i was talking about...yeah mine looks no where near that nice....
 

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I'm don't mean to be a smug git, but this kind of reinforces why I went for an old heckler even though the launch of the new bike was iminent. I figured that the previous generartion bike has had several years of development and hopefully all the weak links would have been ironed out, where as the new one would possibly find a few faults that the lab test kit would have never worked out. I'm a big believer in the 'if it ain't broke, don't fix it' philosophy.
As for the comment on hydroforming, aren't the cracks appearing through the welding?
 

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noMAD man
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True, the cracks are at the weld, but wouldn't flexing below the weld also possibly cause those cracks? I'm no metalurgist or engineer, but I've seen cracks at the weld not always turn out to be just the welding quality. Sometimes they're the result of flex or load issues downstream. Just from a lay person's observation, that web-style hydroforming...or whatever other magic method they used...doesn't look particularly confidence inspiring.
 

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Discussion Starter · #10 ·
TNC said:
Just from a lay person's observation, that web-style hydroforming...or whatever other magic method they used...doesn't look particularly confidence inspiring.
that's exactly why i like the previous gen heckler's swing arm better...just a CNC'd yoke, with a single tube welded to it.....that's it...simple and effective....also, there is less welded area on the old heckler, therefore less "heat affected area", which typically results in less failure....yes i know it's all heat treated afterwords, but as a general rule the less welding, the better....
 

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Have to say unless you guys have seen the finite element analysis of both parts or the fatigue to failure test results it is likely impossible to say which is strong in what ways. Also, the OP is asking for a reason, I strongly suspect no one here will have anything more than a guess as to the reason for the change. Sure everyone could be right, they wanted to reduce weight and it is now too light, but then again we could be completely wrong, at this point it is all just a wild guess as unless someone has access to the design data there is no way to simply look at a part and understand what its strengths and weaknesses are (could be different material, could be different process, could be stronger in different directions or more clearance for other reasons).
 

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Reason for the change? Well the old heckler isn't exactly at the cutting edge of design is it? Santa Cruz needed to get the heckler back up to date, look at the rest of the market, its all swoopy hydro formed curviness now, the old heckler is pretty old school. Bit of a shame really, I prefer my bikes to be straight forward rather than all curvy.
 

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KEEP ROLLING
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its strange that it cracked on the weld usually in my filed of work (industrial engineering) the welds are the strongest point, failure usually occurs right where the weld meets the parent metal not on the weld. It could be a heat treatment "stress reliving" gone wrong ? or metal fatigue due to aluminum's elongation properties, it looks like the weld needs to be thicker in that area to build up the material on what looks like a weak point on the linkage. you can see how thick the weld is just above on the left.
 
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