Thank you... I think I'm gunna need some help from people tomorrow when the shop shrugs me off. I've got a video of it doing it.
There's nothing rubbing. Doesn't matter if I'm peddling or coasting. Could be bouncing up and down on the springs... Nothing really triggers it. So I'll just be booping about and every few seconds there's a fwap like I hit a huge rock...and I can feel it in the handlebars.
To be honest, I don't know what I'm doing...but by the end of solving this problem...I have a feeling I'll know more