My steel BSO has developed a creaking sound when I apply the front brake. I only hear it when I am beginning to brake, when there's not a lot of pressure being generated. I can recreate this sound by pushing the front wheel back with my hand, imitating braking pressure.
All the sound happens while I'm going from no braking to very light braking. Going from very light braking to very hard braking makes no noise.
I'm pretty sure the sound is either coming from the frame's head tube or the fork tube. I have inspected the frame and fork crown. No visible cracks.
I replaced my very weak front brake recently, and I have been enjoying doing stoppies and stuff. Could this have started a crack somewhere? And if so, where is it most likely to be?
After following some of the advice you guys offered, I have further narrowed it down.
I do not have a suspension fork. My headset is not loose. The wheel is not the source of the creak.
I have found that the fork tube is also not the source of the creak, based on the way the sound behaves when the bars are turned one way or the other.
I am almost certain the noise is coming from the frame.
I got it welded, and I haven't had problems since.