Cannondale CAAD 7 Fatigue?

EricE
EricE Posts: 61
edited March 2009 in Workshop
The seat tube on my four year old Caad 7 R700 race bike now has some bubbling under the paint. I'm thinking its terminal but I guess I'm looking for a second opinion. I'll be off to the LBS tomorrow but looking for some hope really.

Also the bottle bosses on the down tube have popped out and there is a 1mm tear in the aluminium around the remaining hole.

Its kaput isn't it?

Cheers,
E

Comments

  • andyrr
    andyrr Posts: 1,823
    The paint bubbling might just be the result of moisture lifting the paint - think paint doesn't stick to alu as well as steel- I have a 10+ year old 'Dale MTB that has been left neglected in garage and then shed. Paint has actually lifted completely from a couple of places but I wouldn't scrap it. Unfortunately mine is a lovely metallic orange so getting it resprayed might be a bit expensive but I wouldn't bin it just for that.
    Yours does have damage which I am not so sure of as the tubes will be pretty thin so repairing that might not be the easiest.
    Good luck - CAAD 7 frames are still not exactly lardy and prob what the pro's were using only a few years ago.
  • Al_38
    Al_38 Posts: 277
    I wouldn't worry too much about the paint bubbling... my caad5 has quite a few areas like this - mostly where there has been a hole /edge through the paint. It is just a sign of metal corrosion below the surface of the paint. however this is mostly benign as aluminium oxide acts as a barrier to further corrosion, this shouldn't effect anything structurally. I am planning on getting mine re-sprayed in the summer - mostly for bike tart reasons (fancy a change to white to match the other bikes)[/i]
  • Monty Dog
    Monty Dog Posts: 20,614
    I'd be more worried about the hole around your bottle boss - sharp edges could lead to crack propogation - at least smooth off any sharp edges/corners with a file. Sadly, as Cannondale frames are heat-treated, effecting a repair in an oversize hole would be tricky - welding the frame could lead to problems
    Make mine an Italian, with Campagnolo on the side..
  • Al_38
    Al_38 Posts: 277
    I believe to stop crack propagation (leading to fast fracture) in the aero industry it is common to drill a small hole at the tip of the crack (they then fill it with a rivet i think) but the round hole reduces the stress concentration factor at the tip of the crack slowing propagation
  • crankycrank
    crankycrank Posts: 1,830
    If you're good at some basic metal fabrication you could make some small patches of thin gauge aluminum or stainless steel, maybe 2-3cm dia., to glue over the bottle boss holes. Contact some aircraft supply shops for some good quality bonding agent for aluminum. Insert some new rivet nuts into the patches before applying so you can use a bottle cage again. I've got some old style friction gear shifter bosses bonded to my 10yr old aluminum frame downtube and no problems.
  • EricE
    EricE Posts: 61
    Thanks for all your help. I like the last idea and may give it a go. Its too good a frame to die on me.

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