Edit: I'm actually saying this as someone who enjoys and actually does bike. When living in the city proper, I think there are very few routes for which the bike isn't the quickest method of transportation. For my commute, which is pretty much a best-case scenario (modern metro with few to no issues, goes in a fairly straight line, don't have to change lines, stations close to both home and the office) the bike is much faster: 20 instead of 30 minutes.
Wouldn't we all love to have such a big flat.
I was talking to a friend living in London, and it would indeed seem that flats tend to be bigger over there. We do have many 100+ m2 flats, don't get me wrong, it's just that most locals can't afford those and live in shoeboxes instead.
There's also the fact that the layout doesn't always lend itself to storing a bike, most flats being rather old. Even though I would technically have the surface area to store a bike, it'd have to be in an awkward place to avoid blocking the passages.
Some newer apartment buildings do have areas for storing bikes more or less securely. But I doubt that's the case for most people.
Instead, what I'm hopeful for, is that the local bike-sharing scheme will improve. And indeed, I've read a few weeks ago that they were rolling out some improved model, which they expect to be more robust.