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  1. #51
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  2. #52
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    Just a thought, could fiberglass or carbon fiber be used to reinforce or repair the rear triangle? Possibly one could just coat their rear triangle in carbon fiber/fiberglass before it cracks.

  3. #53
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    How many of you use bolt up rears? I reckon this would go a long way to tightening up the rear end and stopping flex thet leads to cracking?

    I have ordered 10mm bolt up hope pro ii for mine.

  4. #54
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    Iron Horse Rear Triangle MKIII

    If you would rather get a new rear triangle for your Iron Horse I think I have one.

    Just take a picture of your old one and I will see if I have one for you.

  5. #55
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    FWIW, just found a 10mm crack on my 2009 MKIII just above the weld point on the right chain stay.

    A mate had a similar problem so I knew it was a risk, but the frame was pretty cheap ($400AUD off ebay including shock and headset) and I got 2 years riding so far, and will flog her till she drops .

    Tried to mitigate with a bolt-through axle to reduce flex, but judging from the tire rub on the inside of the frame it was still flexing a bit (or maybe I need to lose some weight

    p.s. found this thread trying to find a new rear triangle ;-)

  6. #56
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    I have a new triangle nib black

  7. #57
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    Quote Originally Posted by clark View Post
    I have a new triangle nib black
    Hey Clark, I have it in the local shop getting a gusset plate welded to see if I can keep going on the triangle, but how much and would you be willing to ship to South Australia?
    Last edited by si618; 09-16-2012 at 08:09 PM. Reason: add quote

  8. #58
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    It cost $200 us from cross lake sales a while back. Black. Could ship to aus if payment was certain.

  9. #59
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    Quote Originally Posted by clark View Post
    It cost $200 us from cross lake sales a while back. Black. Could ship to aus if payment was certain.
    Thanks. Just got the triangle back from the local engineering firm, had a gusset added so will see if that lasts, if not, I'll might take you up on that offer, cheers!

    fwiw, here's a photo of the repair work, which cost $75:
    dropbox.com/s/17mtr8hqhswfzqy/Gusset.jpg
    dropbox.com/s/2lgpms1uuchodod/GussetInside.jpg
    (sorry, my post count isn't high enough to link directly)

    You can see the tyre rub from frame flex on the back chain stay. Also found a way to attach an old tube to protect the frame under the welds, as I was surprised how much it had been scratched from chain slap.

  10. #60
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    had repaired my MKIII 2007 the same as you.
    also added a small plate under the same place.
    works great now for a while.
    I love this frame!

  11. #61
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    Quote Originally Posted by saruti View Post
    had repaired my MKIII 2007 the same as you.
    also added a small plate under the same place.
    works great now for a while.
    I love this frame!
    Have now done a few decent rides with reasonable descents and jumps and the gusset is holding fine. I was a little worried because it hasn't been heat treated, it was too expensive, and would've cost close to what I paid for the frame ($400).

    However, last week I found a 10-12mm crack hiding under the top tube next to the weld to the head tube. I've marked the edges with a sharpie texta to see if it's growing, but I've no idea how long it's been there, as it's pretty well hidden, so it might be ok.

    If the crack grows I'll go back to the same guys in Adelaide who did the gusset (dynamic engineering) and get some plates welded on both sides of the frame between top/down/head tube. It won't look pretty but with a little luck I'll get another year or two extra before something else breaks A mate had an earlier model frame and completely snapped the weld between the seat tube and bottom bracket.

  12. #62
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    damn you guys! i was just fine until i happened upon this thread...and wouldn't you know...this evening i was replacing a shifter cable, thought about this thread and checked over the rear triangle of my 06 MKIII, and sure enough there is a crack right above the weld on the right chainstay!!

    so my question is this...do i need to worry about fixing/replacing the frame? nowadays, I ride this bike maybe twice a month on XC type trails. Lots of roots and rocks, but no drops. wheels rarely leave the ground. i am 200lbs, however. but i wouldn't say i am rough on equipment. i'd just like to squeeze another year or so out of this bike. anybody think its possible? maybe i'll just keep an eye on the crack after each ride. who knows...it could have been there for years already. does anybody know of an MKIII triangle that has completely broken apart? maybe i don't want to know the answer to that question.
    "Pops trippin', he want me to ask for my bike back. You know I wouldn't trip."

  13. #63
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    Quote Originally Posted by biggsmoothe View Post
    damn you guys! i was just fine until i happened upon this thread...and wouldn't you know...this evening i was replacing a shifter cable, thought about this thread and checked over the rear triangle of my 06 MKIII, and sure enough there is a crack right above the weld on the right chainstay!!

    so my question is this...do i need to worry about fixing/replacing the frame? nowadays, I ride this bike maybe twice a month on XC type trails. Lots of roots and rocks, but no drops. wheels rarely leave the ground. i am 200lbs, however. but i wouldn't say i am rough on equipment. i'd just like to squeeze another year or so out of this bike. anybody think its possible? maybe i'll just keep an eye on the crack after each ride. who knows...it could have been there for years already. does anybody know of an MKIII triangle that has completely broken apart? maybe i don't want to know the answer to that question.
    My repair lasted until my first crash last week, it now has a 20mm crack above the gusset weld

    Check the welds on the seat, top, down and head tubes. The crack in my top tube was very hard to spot as it's on the under-side. Mark edges of any cracks with a texta or sharpie so you can track the progress, it's too hard to eyeball unless it's failing fast.

    Not sure anyone can really advise as to whether it's safe or not, you have to assess the risk for yourself. I also want to squeeze as much out of my MKIII as possible, but it's on borrowed time, and some folks think it's not worth the risk. I'm avoiding jumps, rock gardens and gnarly lines until I get a new bike.

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