>No way would I have attempted that on a bike - the increased aerobic activity alone (to say nothing of embers / ashes / etc) would have probably caused crazy amounts of smoke inhalation / death.

Riding a bicycle while wearing an unpowered respirator/face mask is surprisingly easy, especially if it has an exhalation value. It does restrict breathing somewhat, but breathing isn't usually the bottleneck when you're cycling. This might even be the optimal way to escape a fire if the roads are congested.