Earlier quoted context omitted.
Singapore does it just fine. I bike in NYC often and I think it could support mass bike ridership in combination with the subway.
Singapore has a population density of 13,600 people per square mile, where the US has 75. They do NOT "do it fine". It is a mass of teeming people crawling all over each other.
Don't be disingenuous. NYC has a density of 27k people per square mile. Farms in Idaho do not factor into the discussion about cities.