Nah, not even close. Minneapolis has a lot of cyclists who go year-round. Even on the coldest days when the snot is freezing in my nose I'll see a couple of people cycle past me as I commute. After snowfall the main bike paths are frequently cleared first, before any roads. We have multiple bike-only highways that make a lot of travel safer for cyclists.

We could use concrete barriers between bike lanes and traffic, that's for sure, but there are enough options that you can usually avoid having to be in traffic.

It's certainly not even close to the crazy quantity of cyclists we normally have, but it is by no means a non-starter or dead out. Fatbikes really make a difference.

Source: Resident of MPLS.

I've cycled through winters with wind chill in the -15F range and up to a half foot of snow on the ground. So, it is more than doable to do in both those cities.