Do you believe there is any advantages here? One groove in the normal location with a second groove up by the axle head? Anyone run axles like this yet? We've seen other variations, just curious.
Per the title, the first thing that came to my mind was a Disco song Groove thing haha.
However, I am not a machinist but the groove at the head of the axle might be the result of champhering the head of the axle. That's just a guess.
Now for some Disco...haha
All the good ones have a groove at the axle head, they just vary in size..... The one you posted just has a larger grove than most..... the general layout of these are just DD4H 92 copies.
The groove right under the axle head will prevent friction with the outer hub inner ring that cannot be removed in most scout races. Our pack and district bans any hub (outer and inner) work or modification.
The groove under the axle head moves the axle contact point into the wheel bore. Both the grooves when sprayed with pledge attract and hold graphite.