'Tis just a scratch?

[Jon Bond]

Found an interesting little paint scratch on my bike. Probably just a scratch, but the alignment
(parallel to) and proximity (within a couple mm) to the nearby weld makes me just a bit leery of it.

Left chainstay/dropout weld on my Fisher Kaitai (aluminum):

http://www.pbase.com/image/17463392 http://www.pbase.com/image/17463393
http://www.pbase.com/image/17463394 http://www.pbase.com/image/17463395

If you want a major closeup, go to "original" size - 1600x1200.

I can try to get more photos if these are inconclusive too. I'm pretty sure its just paint, but
better safe than sorry. And yes, it is a pretty crappy weld

Jon Bond

 

[Jon Bond]

"Jon Bond" <[email protected]> wrote in message
news:[email protected]...
> Found an interesting little paint scratch on my bike. Probably just a scratch, but the alignment
> (parallel to) and proximity (within a couple
mm)
> to the nearby weld makes me just a bit leery of it.
>
> Left chainstay/dropout weld on my Fisher Kaitai (aluminum):
>
> http://www.pbase.com/image/17463392 http://www.pbase.com/image/17463393
> http://www.pbase.com/image/17463394 http://www.pbase.com/image/17463395
>
> If you want a major closeup, go to "original" size - 1600x1200.
>
> I can try to get more photos if these are inconclusive too. I'm pretty
sure
> its just paint, but better safe than sorry. And yes, it is a pretty
crappy
> weld
>
> Jon Bond

BTW, first picture is with a flash, the rest are not. I think the flash combined with the sparkly
paint makes it look different than it does in person with sunlight or ambient light.

Jon Bond

 

[Jobst Brandt]

Jon Bond writes:

> Found an interesting little paint scratch on my bike. Probably just a scratch, but the
> alignment (parallel to) and proximity (within a couple mm) to the nearby weld makes me just a
> bit leery of it.

> Left chainstay/dropout weld on my Fisher Kaitai (aluminum):

That the feature is so clean is distracting. A crack, especially in aluminum usually produces grey
aluminum oxide making the crack dark. This thing, even if cracked, is not going to fall apart in
the next 100 km so I would wet the "crack" with soapy water (soap is a wetting agent) ride it over
some rough terrain. If the line does not become distinct and darker, it isn't a crack. On the other
hand, the dimpling and crummy weld don't give me any confidence. It seems they hoped the crimp
would hold the dropout but just in case they ran a weld across the end of the tube. Then paint made
everything OK.

Jobst Brandt [email protected] Palo Alto CA

 

[Jon Bond]

<[email protected]> wrote in message news:5wzDa.210$%[email protected]...
> Jon Bond writes:
>
> > Found an interesting little paint scratch on my bike. Probably just a scratch, but the
> > alignment (parallel to) and proximity (within a couple mm) to the nearby weld makes me just a
> > bit leery of it.
>
> > Left chainstay/dropout weld on my Fisher Kaitai (aluminum):
>
> That the feature is so clean is distracting. A crack, especially in aluminum usually produces grey
> aluminum oxide making the crack dark. This thing, even if cracked, is not going to fall apart in
> the next 100 km so I would wet the "crack" with soapy water (soap is a wetting agent) ride it over
> some rough terrain. If the line does not become distinct and darker, it isn't a crack. On the
> other hand, the dimpling and crummy weld don't give me any confidence. It seems they hoped the
> crimp would hold the dropout but just in case they ran a weld across the end of the tube. Then
> paint made everything OK.
>
> Jobst Brandt [email protected] Palo Alto CA

What do you expect for a $700 bike? (outfitted with another 1000 or so in new components... heh!)
The rest of the welds aren't too bad, but that one is particularly ugly.

Most of the cleaning was just me wiping it off with my fingers. Unfortunately, there isn't any rough
terrain around here right now that isn't covered in mud, so the likelyhood that I'll be able to ride
it without it getting covered over in mud, and then cleaned to see it, is pretty slim. Glad I've got
the new bike being built up, and the road bike just in case

I did ride it once (yesterday), but I'm not sure if it got any bigger or not. I think it might have
grown very slightly, but I forgot to take pictures, so I really don't know. Either way, if the
frame cracks there, its not going to be a horrific fall - I might have a nice little walkout, but
nothing too bad.

I'll ride it a bit more and take some pictures after for comparison.

BTW, should I ride it right after the soapy water, or does it not matter?

Jon Bond

 

[Jobst Brandt]

Jon Bond writes:

> I'll ride it a bit more and take some pictures after for comparison.

> BTW, should I ride it right after the soapy water, or does it not matter?

My idea was to generate a natural crack detection fluid, which water in an aluminum crack would
be. Of course you should ride it right away, it isn't supposed to dry out first or it would have
no effect.

There are specific crack enhancing fluids that penetrate well but do not dry. These are oil based
dyes and are usually painted on, then wiped as clean as possible before a chalky quick drying paint
is sprayed on. The dye in the crack will wick into the white coating making dyed cracks highly
visible. Some are enhanced under ultraviolet light.

http://www.magnaflux.com/spotcheck.stm

Jobst Brandt [email protected] Palo Alto CA