"For what it is worth, most people freeze up the first time they are put in a situation like this, and that is after hours of training. It is extremely unlikely you would keep your composure and retaliate with any illusion of smooth execution. More likely you will be laying on the ground pissing yourself. "

Yep, you can't possibly defend yourself, much less survive. It's best to just lay down and piss yourself right this minute. Don't even leave the house first. Geez.

I'll never forget the video of the thugs in DC who murdered a guy for sport on the street corner, then videotaped themselves urinating on his face. (Yes, they eventually went to prison. He's still dead.)

No thanks -- if you want that you've gotta fight for it.

A Kel-Tec or Ruger .380 is ideal for bicycling -- very light, powerful enough, and super concealable. A titanium .38 revolver is another option. And by the way, there is no duty anywhere in the universe to retreat from someone who is advancing to murder you. Don't overthink the "duty to retreat" issue.