My friends decided they were taking bikes, so I did too.
We went for a ride one day, and I was stuffed within 3 km. It then improved a bit, then went up and up and up. It does not matter which breathing technique you use when you are riding up hills. If a bushfire has been through recently, your asthma is not going to be good.
The main road is a highway with narrow shoulders and lots of trucks/caravans/boats. The only other option is very pretty but solidly up hill.
We then had to climb a stoopidly steep (short) hill to get back to our accom. I am thinking about 18%.
All up we rode about 25km. We then stashed the bikes and did beautiful beach walks instead every morning.
It is a beautiful part of the world, but definitely not bike friendly.