The 'self-created airflow' INCREASES the rate at which you gain temperature. Windchill is only 'chill' when the ambient air temperature is lower than your core temp.
To cycle on a summer day, you need to slather yourself in SPF-40 sunscreen including underneath clothing, wear SPF clothing, and make sure to be constantly drinking water. And when you get to your destination you're definitely going to need a shower. I'll take public transport over that, thanks. So does the majority of people.
[0] https://en.wikipedia.org/wiki/Evaporative_cooler#Physical_pr...
Funnily enough I was thinking that about you, because on 40+ days we've got people out riding, overcrowding beaches, walking and some even sunbaking, many will be doing that without shirts on in the open sun and they're not going up in flames. Some poor buggers even have to work outside doing physical labor on such glorious beach days. Personally on days like that I like to go for a quick swim and spend the afternoon with a beer on a bowling green if I can. We've been doing this for generations, my great grandma was doing it before cars, sunscreen and aircon were invented and kids had to walk to school, indigenous people were doing it much longer. We aren't scared of the sun as our skin cancer rates will testify.
Of course these days there's people that take the doona off in the morning and enjoy their air conditioned house, run to their air conditioned car to work in their air conditioned office for 8 hours then do it all in reverse and never see the sun. Of course they don't climatise because they're living in a different climate.
The more wind you experience (or the faster you ride your bike) in those conditions, the more work your body needs to do for maintaining homeostasis via sweating. You will certainly not perceive a >39c wind as a 'cooling' wind in any conditions, and the faster that wind is the hotter it will feel.
The efficiency of sweating depends on rel. humidity. Not what's being discussed here.
The fact that increasing airflow will increase the rate at which you heat up (and how much heat your body must shed) if that airflow is hotter than your core body temperature is just physics 101. Why do you think fan-forced ovens have lower cooking times or temperatures in recipes?
And then you have most populated regions in Asia with 40 degree summers with air so humid that taking a deep breath makes you cough. People still ride bikes, but there are days where it’s deadly to do so for long distance commuting. That’s not including typhoon periods where you’re liable to be whacked with debris and die (because work isn’t canceled for any reason).
Skin cancer is estimated to kill 1,725 in Australia in 2019 [1].
During 2018 there were 1,135 road deaths [2].
I think we could reduce the number of road deaths far faster than the number of skin cancer deaths would increase.
[1]: https://melanoma.canceraustralia.gov.au/statistics [2]: https://en.wikipedia.org/wiki/List_of_motor_vehicle_deaths_i...
Which would become closer to 18% if the number of individuals exposed to prolonged sun time doubled (e.g. by promoting Cycling). We literally run public awareness TV campaigns telling people to stay out of direct sunlight as much as possible regardless of what protection they're wearing.
I don't think you realise it but you're proving the point.
Bikes are fine when the weather is favourable, but a lot of the people commenting here just don't grasp the fact that in some parts of the world, unfavourable weather doesn't mean you might sweat a bit, it means that the weather will make you sick and kill you in short order. The same people that dismiss warnings when visiting countries like AU and then leave with their skin peeling off.
edit: Or bicycles with roofs, similar to the car solution?
I guess that you've never been on a bike on a very hot day. It's much, much more pleasant to be ventilated by your self-created airflow on a bike than it is to to have sweat pouring down your back as you walk around.