Will sanding 0.4 of the diameter of a seatpost make it dangerous?
I don't really know - but: When you suck your thumb, unles your nose is stopped up I don't see how that could cause hypoxia, cuz you are still breathing thru your noseI sleep with the blankie over my headIt's just one blankie thoughIf you really are worried about that you could always wear a baseball cap on your head with the brim pointing forward so you have a gap between your face and the blanket.
Even sanding off .2 mm is too much, and I speak from experienceI tried to sand down a 30.0mm post to fit a 29.8mm opening and the bugger snapped the very first ride after about ten miles of light XC ridingleaving me no seat the ride back on You do sound like you've already made up your mind though so go ahead and give it a shotjust keep in mind that when it does snap (and it will) you'll have a relatively jagged piece of 'thick' 6061 T-6 aluminium aimed right at your nutsGood luck with thatEdit- My opinion hasnt changedManufacturers use as little material as possible while still maintaining structural integrity but you seem to be convinced that you know better soDo what you want you want man, it's your nutsack and it isnt going to hurt any of us when it fails.
I sucked my thumb till I was about 7 yrs old and as a result I've got a slight overbiteDo whatever you can to quit the habit.
