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How to tell if my frame's cracked?

Discussion in 'Downhill & Freeride' started by Spunger, Jul 5, 2006.

  1. Spunger Git yer dumb questions here

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    Well.........I think it happened......won't say what brand so don't ask, but how can you tell if you're frame's cracked? Today while changing out a bearing on a linkage I noticed some small cracks in the powder coat around the seat-tube area welds and the shock mount. I was like........F*$&*#$ because the powdercoat is clearly cracked. I'm assuming it's a crack but not 100% sure. What really pissed me off was a crack as well on the rear chainstay. So I knew my 2 year old frame now bit the dust.

    What really shocks me is I've done no drops, no jumps, nada of that sort (I have other bikes built for that stuff) and this was simply a trail rig. Nothing but riding to the trail and down it (mostly XC'ish stuff) so when I found these possible cracks I got worried.

    Do cracks in the powdercoat usually mean a crack in the material? What places can you ride with a crack and without one? In my case of a shock mount and the seat-post mount (which is a interupted seat tube) I don't think that these cracks I can ride with. Hell I could be riding climbing a hill sitting and have it just give away. Same with the shock.

    Just curious, I've read alot about cracked frames and such but can't find too much info on the symptoms of a cracked frame or what to look out for and watch for.
    #1
  2. Rik New Member

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    Get a sharp knife and flake back the powdercoating around that area. Don't sand/file the paint away as you'll obscure any cracks, make sure you flake it away. You may be able to use a dye/paint, drip it on the area and wipe it off to see if there's a crack.
    #2
  3. vitox New Member

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    well if the paint is cracked in a pattern that you would tend to think of as a place where the frame could eventually fail, or where other frames crack, you really should at least take the paint off and have closer look, ideally, take it to someone knowledgeable or that has cracked frames before.
    #3
  4. Nick My name is Nick

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    remove the seatpost and fill the frame with water.
    hold the bike up in the air and watch for leaks.

    you're welcome! :thumb:

    "What places can you ride with a crack and without one?"
    None safely, at least not for long.

    just kidding about the water ... I hope you frame isn't really cracked. I guess the only way to know for sure is to chip away the p.c. and inspect the metal.
    #4
  5. konabiker New Member

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    Is it an older cortina?

    That will pretty much answer the question.
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  6. Spunger Git yer dumb questions here

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    Nope, I'm not gonna bash/praise any manufacture until the end :hot:

    I've made a few calls and emails, just waiting for a response. I guess either way, a stress mark where it cracks the powdercoat is no good, and in the area's that it decided to crack are areas in which I'm not going to go for.

    I'll see about chipping away the powder coat in the areas where the cracks are.
    #6
  7. Kornphlake New Member

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    It doesn't really matter if it's just the powdercoat that's cracked or the metal, if the finish is starting to wrinkle or crack it means the tubes have either cracked themselves or stretched/bent in some way. Either way your frame isn't safe to ride. Unless the bike is steel I'd say don't ride it on anything. I'm sure you've seen just as many stories about the guy who rode off a curb and his headtube ripped off as I have. Fatigue failures can happen at any time, there isn't really any way to estimate how long until catastrophic failure once you've seen signs of fatigue.
    #7
  8. Spunger Git yer dumb questions here

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    That is what I was looking for. I have heard those stories, and I don't want to be one of them (instead of head tube seat tube). I figured that the powder coat cracked because of something, weather it be a stretch, crack, stress mark whatever. I won't take my chances.

    Nope, it's not steel. At times I wish it was because I know if this happened it'd be a quick fix (just re-weld it) but being alum. it's not that easy. It just sucked because usually you don't find these "cracks" on both the front triangle and rear triangle. That was the real bummer because I could have salvaged the frame if only one part was cracked, but not both.
    #8
  9. Spunger Git yer dumb questions here

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    Well it's cracked, I chipped away some of the powder coat and sure enough it's cracked. :(

    To repair the frame it'd cost $400-450 and that's on a 4 year old frame. So it might be time for something new'er than that.

    Oh well, thanks again guys for the hints and tips on making sure it's cracked. I just think the frame saw better days, atleast it didn't crack and fail so bad that I couldn't keep riding it out of the trail.
    #9
  10. kidwoo Celebrating No-Pants Day

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    Well it IS an m1 you know. :D

    You got the seat tube though? That's a new one.

    4 years on any dh frame is a good run.

    Sorry to hear about it.
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  11. Spunger Git yer dumb questions here

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    I think that's how I have to look at it, 4 years on any alum. frame is a good time span. Even though I would have liked it to have lasted longer I guess it's ok.

    I guess it's time to save for something else :)
    #11
  12. WestCoastHucker Active Member

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    daydreaming about a new rhythm line.....
    why did you feel the need to jive us with your "2 year old" frame nonsense, then come back to tell us it was over 4 years old?
    #12
  13. LaharDesign New Member

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    Look people shouldn't be too shy about welding up a cracked alloy frame.
    Very few aluminium frames are heat treated after welding these days and if its a 7000 series its Impractical to do that and so never done.
    whatever your frames made of just clean the powdercoat off for an inch around the cracks, file a v groove where and past the ends of the cracks and have someone tig weld them up. Ask for a nice smooth fillet with low temp silicon alloy rod and you'll get a better result than new. Other places may develop cracks so its not quite like new.
    #13
  14. kidwoo Celebrating No-Pants Day

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    What?

    Like EVERY 6000 series aluminum frame.......which there are a lot of.....including intense don't get heat treated?

    Sure a few use 7000 series but just as many or more use 6061. And 6061 is REALLY fun to ride without a heat treat.:cool:
    #14
  15. LaharDesign New Member

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    full cred to boutique companies that do heat treat after welding.
    Its still worth welding these frames up if they crack outside warrantee.
    #15
  16. Spunger Git yer dumb questions here

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    I got the bike in late 2002 (from email records). I'm lucky if that bike saw 30 trail rides in it's lifetime (as I ride my other bikes more). I'm still more suprised and shocked that something with as little riding as I've done has cracked in the spots that it did.

    I couldn't remember how long ago I bought the bike. I just know how many time's I rode it. Clearly it wasn't much.

    I just marked it and figured I'd watch the crack, if it moves then I'll stop riding it but for all I know the cracks have been there for a long time and I just never saw them. If they move after a couple rides then I know it's time to retire it.
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  17. kidwoo Celebrating No-Pants Day

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    The chainstay crack.................don't ride it man. ..........just above/in front of the crossbrace to the horst link right?

    Retire it.
    #17
  18. Spunger Git yer dumb questions here

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    Nah, upper shock mount, it's pretty small.......I should take a picture & a section on the seat mast/gussett area. Hard to explain but I'll see what I can do about a picture.

    The only 2 things that will happen is the shock mount will shear off causing me to have no shock OR the seat tube (interupted seat tube) would rip off. I only ride this bike on XC'ish trails and the road so I dunno, that's what made me think of taking my chances.
    #18
  19. sharkdh New Member

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    You'd be amazed how hard XC and trailriding is on frames and linkage. I've ripped frames in half by climbing 12 RPM up steep hills.
    Just keep an eye on the cracks. If they start to grow you'll know its time...Until then just ride it till the wheels fall off.
    #19