This is a very simplistic solution to a really complicated question. I say this as a cyclist myself.
Cycling is great for short commuter trips. But it doesn't replace long trips at all, not practically anyway.
Cycling, while great for your health, consumes extra calories that you wouldn't otherwise have to expend. That extra food has its own carbon footprint. Depending on your diet and where it comes from, that extra carbon footprint can actually be quite significant.
Cycling reduces congestion. No argument there.
Even if you cycle, you are probably cycling to local stores that have their merchandise driven in on big trucks. It's still probably more efficient this way, but far from net zero. Remember that the environment you live in is still mostly powered by gas guzzling equipment. That equipment will need to be electrified.
And that's my point. Cycling is not a one size fits all solution. It is one piece of a much bigger puzzle.