What is the difference b/w dropout diameter(9mm) and 3/8"(9.478mm) Tpi bicycle axles I am creating a ski-bike and taking this website as a reference: Alpine Ski-Bike.

I am having some trouble understanding some things, as it says that 


  "it fits in 100mm x 9mm front dropout"


but then it states that 


  "Mounting triangles and foot pegs are extruded 6061 T-6 aluminum. They
  use standard 3/8" 26 thread-per-inch bicycle axles (140mm and 175mm
  lengths)"


I have two questions:


The mounting triangle uses a 3/8"(9.478mm) bicycle axle but the front dropout is only 9mm so how is it supported?
I am asuming that (140mm and 175mm lengths) = 140mm length of mounting triangles and 175mm length is of foot pegs, so is 140mm is the length of bicycle axle?
I just checked two frames and forks drop outs. They all measured at least 9.5mm. They all allowed a 3/8" bolt to pass through. If you are having doubts about your particular frame, get a 3/8" bolt and see it fits. You also need to verify that the nuts will sit correctly in the front fork.The nut must sit flat on the fork not on top of the safety tabs (also called lawyer lips).