Why? I live in a city and also bike around 10km a day to go to work and back home. I'm not really fit and this city isn't flat either, neither do we have showers at work haha. You just get used to it after a while, really.
Every single biking thread on HN ends up with the same arguments: well, it doesn't get freezing where you live, well, it doesn't get to 45C where you live, well, you don't have hills where you live.
People bike in any kind of environment and terrain, it's up to you to understand that ultimate convenience is not the bike's proposal, it's a simple, reliable, and fun tool to use to transport oneself when walking would take too long.
I live in a hilly place, with freezing winters (Stockholm), and I bike every single day of the year. I need 2 bikes for that: one for when it's not frozen outside and another that can take me safely on frozen/snowy ground. That's it.
When I lived in Brazil I also used to bike, in 30-40C, on a very hilly city (São Paulo) that was absolutely not made for cycling, we barely had bike lanes at that time in the city, it was still doable when distances were anywhere between 2-15km.
So yes, it's not the ultimate convenience as sitting inside your own personal refrigerated metal box but it's absolutely doable.
I mentioned this in a sibling comment: I live in Texas. Where I live we had 43 days in a row above 40C this summer. But the heatstroke chance is not even the major risk when biking in Texas. It’s that everyone here drives massive cars that are not at all designed to save bikers lives if they get hit. Many people here drive $80,000 USD trucks or SUV’s at speeds and levels of carelessness that will easily flatten cyclists. Ignoring the fact that we have a culture here that is actively aggressive against cyclists (there are people here that actually target cyclists, seriously, and there is no repercussion for them for running a cyclist over), there is, like Brazil, simply no biking infrastructure here.
So yeah any starry eyed biking idealism dies in Texas.
I also lived in Sweden (Malmö) and it was fantastic for biking. Sweden is extremely spoiled for biking infrastructure, however. In Malmö you get dedicated bike paths that are separated from the road in a raised manner (eg above the curb) and also from pedestrians. The biking infrastructure in Sweden is probably second only to the Netherlands or Denmark in that regard. And the gap between what these countries offer and what something like the USA or Brazil offers is just massive, as you almost certainly already know.
I agree that most weather situations are pretty tolerable for biking. But there are some extreme temperatures (40C, -20C) that are not conducive to biking. As long as where you live doesn’t have that as a decent chunk of a season you’re fine to use it as a commuting tool, all other things considered. The problem is really rather whether getting on the road makes you actually legitimately in a statistically founded fear for your life, as is the case in Texas.
My original comment was about cheap bikes no one wants to steal. Realistically for mass bike use ebikes are the way and that solution doesn't work. Ebikes are targets for thieves.
I live in Toronto and we regularly get to 35C with high humidity some summer afternoons: not too much of a problem if ride is <1 hour. Just hydrate (perhaps when you get home).
Or just don't cycle on the hottest days, but only on the 'reasonable' ones.
I live in Texas, where we had 43+ consecutive days of weather over 40C this summer.
I actually don't think the weather is even the limiting factor here in Texas. It's that it's literally unsafe to ride a bike on the vast majority of streets here under fear of serious injury or death.