This has been informative. I carry Presta-to-Shrader adapters in my tool bags, but never use them. All of my pumps have Presta heads. Back in the 80s, you needed the adapters because often the pumps didn't support Presta.

But now, I have to go back through my various adapters and make certain that they seat properly in relation to the inflation needle (as described above by FB and others). Better to know in advance, rather than fiddling with one that doesn't work right in a pinch.

Thanks, all, for this thread. PG