Looks like a paint crack, but the best way to check is to tap the frame with something metal (like a coin or screwdriver blade) and listen for a change in the sound as you move over the "crack." Now that you know how long the "crack" is, watch whether it grows. If the frame is cracking then the gap would possibly grow in width as it lengthens.I was cleaning my LOOK 675 the other day and spotted a hairline crack on the BB area (near the downtube/bb intersection). I could sorta feel the crack with my fingernail but its shallow. How do I tell if it's a paint or carbon crack. I appreciate your advice. (pics included
I do believe a paint crack can grow. Visually, it looks like a paint crack. The tap test sounds like it should be ok, but the only real way to know is to strip all the paint off to have a look or X Ray the frame.I've tried the coin tapping method, and didn't notice any abnormal sound. Is there a possibility that a paint crack will grow?
that's actually a ingenious method. thanks for the tipHere's a method which worked for me.
Place a piece of invisible Scotch Tape over the crack.
Find an opening in the frame that will allow you to squirt a good shot of a colored fluid such as Liquid Wrench, into the area on the inside of the tube.
Position the frame such that the crack faces the ground and the liquid can "puddle" in the area of the crack. Let it sit for an hour.
When done, inspect the Scotch Tape. If it's a crack in the tube, the fluid will bleed through and stick to the tape.
Here's the tape from my frame's headtube, where I suspected a crack.