i watched a video about bike fits, and one of the things they said, once in position of riding, when looking down , the front wheel's hub should not show, and the handle bar should cover the sight of the hub, is this true ?
in addition, if when looking down the hub shows in front of the handlebar, bike could be too big, if it shows behind the handlebar, bike is too small.

For me personally it shows in front, just a hair like an inch when looking down, but my elbows are not fully locked.