Carbon fibre frame and corrosion

spike_Brown
spike_Brown Posts: 2
edited August 2015 in Workshop
Hi,

My wife surprised me last night with a Specialized Roubaix Comp she found on eBay, she knew I was looking for one.

Problem is I didn't get to check it out before hand and have noticed some corrosion on the steat tube stays.

20152511910_bae0d8ccc5_z.jpg

And

20152513190_ca9db8e985_z.jpg

Comments

  • sungod
    sungod Posts: 16,873
    tbh the picture looks silvery, like it's been abraded, rather than powdery white, but perhaps that's just an effect of the lighting

    if it's cf with aluminium alloy inserts, there's a risk of electrolytic corrosion where they interface

    you need to figure out if this is 'only' surface corrosion on exposed al, or something nastier than could be damaging the al-cf bond - the corrosion product takes up greater volume than the original al, over time the edge of the corroded area may creep under the bond and destroy it

    i'd clean the corrosion back to bare metal with fine abrasive, then look closely at the edge, if the cf is lifting/distorted it'd be a bad sign, if it looks ok then flush with clean water to remove any salt, allow to fully dry, then solvent degrease the area and 'paint' it with epoxy to seal it

    but there's a chance the al will have been weakened, once the surface is roughened fatigue cracks may form more readily, i had an al downtube bracket go that way, fortunately noticed it before it failed
    my bike - faster than god's and twice as shiny
  • First.Aspect
    First.Aspect Posts: 16,011
    Its very likely only cosmetic - road salt and water getting under the paint of the aluminium insert.

    Rub it down, satisfy yourself that the joint itself is okay, and paint over it again with some car touch up paint or something like that.
  • Monty Dog
    Monty Dog Posts: 20,614
    Quite common - rub down to bare metal, primer and respray. I would be more worried if there were longitudinal cracks along the tube, where there's corrosion inside the sleeved joint and the expansion cracks the tube.
    Make mine an Italian, with Campagnolo on the side..