And yes that is normal that if you just bend (by applying a Flow deformation) a shape that areas to the inside of a bending area will be compressed and areas on the outside of the bend area will get expanded, that's basically just how deformation works. Sometimes if you don't want that kind of deformation happening it can work to only bend a path curve and then build new sweep structures around that deformed path rather than deforming whole already built pieces.

But for your case here I don't think you want to be doing any of that stuff at all though, if I understand what you want correctly. I think you just need for the bottom of your red piece to have the shape of an extruded gear.

- Michael