I know this could go in the Mechanics sub-forum, but out of respect for all the wisdom I'm getting from the 50+ group I would like to ask y'all this question.
While riding yesterday I happened to look straight down and noticed the distance between my crank-arm and the bearing assembly where it passes through the bearing assembly in the frame (is that called a bottom bracket?). It seemed like quite a distance and I wondered if this was normal. My non-scientific measurement makes it out to be 5/16 to 3/8. In case I have totally messed up the description I am including two pictures which should be worth a couple of thousand words.