i dont see that anybody adressed the question .if you have a cracked frame and are doing a good click when it decides to fail you could end up with a steel post in your leg or worse.
sorry to be a downer . we used to use a magnaflux to check the engine blocks and heads for cracks . so here it is reall simple a magnaflux is like a u shaped magnet with one north and one south pole ,there is a pink dust ,basically metal shavings with color in them and when you put the magnet on a pipe squirt some dust on if theres a crack the dust will line up on it due to north and south poles .hopefully i didnnt make it sound to complicated. its really just a big magnet and some metal shavings. hope this helps.