Really fine explanation!IME, like you said, duller blades, razors with more blade flex and chatter and less blade curve seem to cause more problems for me.
Case in point...my Fatips have a curved blade, are very aggressive, super rigid blade and shallow shaving angle. And I NEVER get a razor bump or ingrown hair.
The Karve CB with D plate has a much flatter blade plane, but despite being a very rigid blade design, it caused more of a tugging sensation even with sharp blades and caused bumps on my neck.
My ATT M1 nevr gave me bumps wit any blade despite a non-rigid design and a flatter blade plane.
Duller blades definitely can cause issues, but I find the razor to be more of an issue in most cases. A Voskhod in the Fatip shaves great. But the same blade in a DE89 tugs.
There is no firm rule...only loose guidelines at best and in reality, I fi d each razor/blade combo to perform slightly differently...only one way to figure it out...test, test, test.
Sent from my SM-G960U using Tapatalk
Typically, razor bumps are caused by ingrown hairs. The hair gets cut below the skin level and then as it grows back, it grows into the skin and causes a bump. This is usually more an issue with multi-blade carts that lift and cut the hair.