Originally Posted by ieatrats
I had the impression that the rear entry fork ends were in case the wheel slipped you wouldn't lose it and crash. Makes sense on a track bike where you're putting enormous energy into a sprint say, or a bmx with tricks and jumps and stuff. Maybe I just made that up.
And they look cool, almost as cool as a horizontal dropout conversion bike.
AFAIK this has been debunked by armchair analysis on this forum though perhaps it may be a possibility. The idea is, if one of your track nuts or dropouts fails, the other one will still be there to hold on regardless of which direction the dropout is facing. So your axle will slide back, and your wheel will go into the chainstay (but not fall off) and you will go into a skid, whether you have track ends or not.
It seems to me like track ends are just the most bone simple way to mount a rear wheel on a ss bike that allows for adjustable chain tension, and that's why they are the oldest and still frequently used. But I'm far from certain so I would appreciate it if someone who knows what they're talking about would pipe in.