KHS Aero Crack

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  • Hey y'all. Long story, but I basically ended up with this cracked frame for free. The crack is down at the BB shell, around about a third of the seat tube. I've always loved these old KHS frames, and I'm hoping to bring this one back to life.

    Does anyone have some advice on repairing an old aluminum frame? I know how difficult it is to repair aluminum (finding the right filler material for the alloy, heat-treating, stresses at the heat-affected-zone, etc) but since I've got this frame for free, I'd love to repair it. Whether it's a proper repair, or a bit of a bodge is kinda up for debate.

    So what does the LFGSS thinktank have to say? Any ideas what series alloy these old frames are made from?

  • Urgh, that’s a really awkward place to get to. Ideally you’d want to drill a small hole at both ends of the crack, grind a vee into the crack and tig weld it end to end. The paint needs to be off the area and it needs to be immaculately clean to weld.

  • How critical is it that I find out the type of alloy (6000, 7000 series, etc) for a decent weld job? I've tried contacting KHS but never got a response, and haven't had any success searching the internet either.

    All I have to go on is the "Lite Concept - Aluminum Alloy" sticker pictured above. I know most KHS frames from this era were made with True Temper, did TT ever do an aluminum tubeset?

  • I have the same problem with a Stoemper frame I used to race crits with... Cracked both chainstays at the dents where the tire is located. Hangs on the wall for 2 years now with the idea "it will get fixed someday..."

    Never got to that point just yet.

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KHS Aero Crack

Posted by Avatar for bolognium @bolognium