Any tips for telling whether a crack is the paint or metal?

[LikeClockwork]

Cleaning up my newly acquired frame, as you do, and I've found what appear to be cracks, around the underside of the seat stays where they meet the seat tube, and also where the down tube meets the head tube....wouldn't be able to get decent pics of it as camera is playing up.

Thing is, the paint is very thick, so could it just be a crack in the paint from flexing (steel frame)? Is there a way to tell? I don't mind removing paint as it's pretty rough anyway. There is a fair bit of 'worming' under the paint in places too....

 

[MADJEZ]

Not very scientific but try spraying something nice and thin like WD40/GT85 at the crack and see if it goes through and runs out the frame tubes. I'm sure someone with more engineering nouse can give you a better tip but I'd start there.

 

[LikeClockwork]

Re:

Wasn't sure if the cracks were big enough for anything to actually run out of them, but I've just spent a bit of time with a file and some emery and removed paint, can't be sure but looks like the cracks were just in the paint.... :facepalm:

 

[fjpshaw]

Re:

It's annoying to have filed back the paint only to find the 'crack' wasn't in the metal after all, but at least now you can be reassured that the arse end of your bike isn't going to collapse once you have it up and running!

I'd have done the same. Plus, given where you've said it is, a paint repair job won't be noticeable.

 

[LikeClockwork]

Re:

Have changed my mind, at least about the one at the head tube/down tube weld... :cry:

Looks like a crack following around the weld...can't face it right now, although it is probably repairable, so it's just been hung up in the work shop. Shame, as this was something I'd waited a while for, but there you go...

 

[fjpshaw]

 

[LikeClockwork]

Re:



Sure is!!

 

[fjpshaw]

Re:

Defo repairable though (he says having not even seen the issue :roll: ). Think you said it is a steel frame? A good welder could flush back the existing weld, run in a new one, and dress it within a couple of hours tops.

Good luck, hope it works out!

 

[LikeClockwork]

Re:

Thanks mate, this is the discussion I've been having with a few others, but you know how it is, it's just put me off it now and I've hung it up in the workshop to teach it a lesson....I do know someone who could fix it, but it's not happening this weekend that's for sure, and I wanted it built up and out there by tomorrow!!

Bit more worried about the cracks around the underside of the seat stays, as that's going to look all 'gobby' once it's been welded up, if anybody could even get in there properly

 

[dyna-ti]

I think people would be surprised if they say xray'd their fav cannondale
Found mine to be spidered with minute cracks and that was when new. Went on to hammer it on a daily basis before i sold it 3 years later. I think cracking and metal go together
I take it this is alloy ?


Something handy to have
Go to a good camera shop and buy a good magnifyer. Forget the plastic affairs, i dont think theyre even the correct magnification.
x8 and x15 will let you know it its a scratch or a crack