I've commuted by bike for sometime. Not a tremendous achievement as I don't have a long commute.

It would be great to have practiced the optimal route in advance (which may vary depending on the particulars of the cause of evacuation). That's true with walking, too. The commute will look, and feel, a lot different when not driving it.

Even if someone hasn't been on a bike for thirty years and has no intention of practicing in advance of bugging out by bike, an old beater bike kept for emergencies is going to beat not having one.

Padded bike underwear would be worth their weight in gold, too. Even at today's gold prices.

No matter the bike, in an emergency I'd rather ride than walk 10, 20 or 30 or more miles.

I've had colleagues with 80 mile commutes. A lot of hilly walking. Doubtful they have a plan. Most peops don't.