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  1. #41
    Senior Member Nobby's Avatar
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    [IMG] CIMG3894 by jhodonnell, on Flickr[/IMG]
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  2. #42
    Senior Member Nobby's Avatar
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  3. #43
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    Pffft there is a bigger crack than that on my Carbon Trek, mere flesh wounds bit of Nail polish so water doesn't get inside and it still rides like a belter.

    :-)

  4. #44
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    I've read many an articles on the subject but there are no definitive results. Sure, there are the famous cases you mention and it seems to be regular issues which suggests design fault, but there are just as many folk claiming longevity, although those expecting a bike for life, as I previously mentioned, are barking. Like I tried to point out, though - it's not just one material and even if the industry attempts to make some sort of comparison they're going to be up against folk not bothering to report failure as they feel their frame 'had a fair lifetime' - that will produce inaccuracies, surely.

    But, for balance...

    Another quick Google

    ...and another.

    Interesting how some of the carbon frames have cracked in a similar place to some of the titanium ones.

    Anyway, enough of this pointless hate of Ti - it's...er...pointless. Just allow folk to buy what they desire without pointing out pointless pointlessness. Please - it gets awfully tedious and more than a little predictable.

  5. #45
    Senior Member Stan's Avatar
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    Just allow folk to buy what they desire without pointing out pointless pointlessness. Please - it gets awfully tedious and more than a little predictable.

    There endeth the need for all bike forums.
    aka Sean / Sandeep / Sylvian / Seamus....

  6. #46
    Senior Member Stan's Avatar
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    That picture of Nobby's is obviously a minimum seatpost insertion issue with either the rider or a fault with the design. Not "because it's Ti".

    Its clearly a stress fracture caused by the top of the seatpost being pulled in the opposite direction to the top tube beyond its design limitation which should be prevented by the bottom section of the seatpost being supported in the seat tube underneath the top tube.
    aka Sean / Sandeep / Sylvian / Seamus....

  7. #47
    Senior Member Nobby's Avatar
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    Quote Originally Posted by Stan View Post
    That picture of Nobby's is obviously a minimum seatpost insertion issue with either the rider or a fault with the design. Not "because it's Ti".

    Its clearly a stress fracture caused by the top of the seatpost being pulled in the opposite direction to the top tube beyond its design limitation which should be prevented by the bottom section of the seatpost being supported in the seat tube underneath the top tube.
    You'd think so, wouldn't you. It was replaced under warranty because a) that was not the case & b) it was not the first.
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  8. #48
    Senior Member Nobby's Avatar
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    Quote Originally Posted by Hans Frii View Post
    Anyway, enough of this pointless hate of Ti - it's...er...pointless. Just allow folk to buy what they desire without pointing out pointless pointlessness. Please - it gets awfully tedious and more than a little predictable.
    Oh I don't hate Ti, far from it. Just seems to me that, unless you look at the very top end of production, it is less suitable for bike frames than more modern materials.
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  9. #49
    Senior Member Nobby's Avatar
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    This article is quite good as an exlanation of what I believe is the issue. This phrase is a good summmation:

    "The fundamental problem in welding titanium alloys is the elimination of atmospheric contamination. Contamination of the weld metal and the adjacent HAZs will increase tensile strength and hardness but may reduce ductility to an unacceptably low value such that cracks may occur even in conditions of only moderate restraint. The most likely contaminants are oxygen and nitrogen, picked up due to air entrained in the gas shield or from impure shield gas, and hydrogen from moisture or surface contamination."
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  10. #50
    Senior Member Stan's Avatar
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    Quote Originally Posted by Nobby View Post
    You'd think so, wouldn't you. It was replaced under warranty because a) that was not the case & b) it was not the first.
    Like I said, it could be (and obviously was) a design flaw, but that isn't exclusive to Ti. For example, the (steel) Kinesis Decade Versa Mk1 goes in the same place due to a combo of the material thickness and seat clamp design.
    aka Sean / Sandeep / Sylvian / Seamus....

  11. #51
    Senior Member Stan's Avatar
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    Quote Originally Posted by Nobby View Post
    This article is quite good as an exlanation of what I believe is the issue. This phrase is a good summmation:

    "The fundamental problem in welding titanium alloys is the elimination of atmospheric contamination. Contamination of the weld metal and the adjacent HAZs will increase tensile strength and hardness but may reduce ductility to an unacceptably low value such that cracks may occur even in conditions of only moderate restraint. The most likely contaminants are oxygen and nitrogen, picked up due to air entrained in the gas shield or from impure shield gas, and hydrogen from moisture or surface contamination."
    Makes sense as to why Enigma recommend Carbon posts in their frames then. Also makes sense of their lifetime warranty.
    aka Sean / Sandeep / Sylvian / Seamus....

  12. #52
    Senior Member Nobby's Avatar
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    Yep.

    Talk to any welder & they'll tell you that it's almost impossible to remove all potential contaminates during the process without going to great expense and much longer production times. The areas most affected on bike frames are those that see the biggest exposure to heat & the top of the seat tube has welds for both the top tube & stays.
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  13. #53
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    Quote Originally Posted by Nobby View Post
    Yep.

    Talk to any welder & they'll tell you that it's almost impossible to remove all potential contaminates during the process without going to great expense and much longer production times. The areas most affected on bike frames are those that see the biggest exposure to heat & the top of the seat tube has welds for both the top tube & stays.
    ^^

    I'd better mention this to the missus before I finally go ahead and order the new 29er frame :-/

  14. #54
    Senior Member Nobby's Avatar
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    You're buying a Ti 29er?
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  15. #55
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    No, I'm building a (Spare parts everyday trail bike) Steel 29er with carbon forks...

    But if the missus's knows that welding causes a reduction in strength I could try and convince her to let me get a Dirty Harry rather than another Inbred :-)
    Last edited by BHB 10.6.6; 01-05-13 at 09:49.

  16. #56
    Senior Member Nobby's Avatar
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    I'm afraid steel isn't affected that way, it's the Ti that has issues.....

    .....but clearly she doesn't need to know that.
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  17. #57
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    Almost dropped-off into oblivion...

    Yeah, I read an article very similar to the one you linked to, Nobby. Didn't put me off buying a frame made of the stuff, though. : ) I know someone that has experience in welding Ti, so any doubts I had were put to rest.

    On another note and probably shouldn't be writing this in a public domain just yet but...an industry insider working for a major aircraft manufacturer has informed a friend that carbon fiber is starting to show signs of failure, in particular the glues and resins. In his words - "...if it isn't good enough for planes then you can bet your arse it isn't good enough for bicycles." He also took a gander at the Santa Cruz test and pointed out something interesting - the first cracking noise on the aluminium frame is around the 787lbs mark. The carbon's first noise is 814lbs; not a huge difference if you consider both frames are beyond use at that point.

    's got me twitching considering I use carbon bars and posts on all my bikes...

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