My bikes does reduce my carbon footprint to some extent. My job involves driving so I have no choice while at work, but once home the car now sees little use, most shopping and social trips being done on the bikes, but like Grizz the main reason for doing it is because I like it.
I don't think there can be any doubt that e-bikes, even with no rider assistance are much greener than public transport, at least for most of the time. Petrol & diesel fuels contain about 40MJ of energy per litre, that's about 11kWh or 28 charges for a typical e-bike.
So, assuming the bus carries an average of 30 passengers and does 4 miles per litre each passenger is doing the equivalent of 120 miles on 11 kWh of energy or about 11 miles per kWh. (Most of which is wasted as unwanted heat)
By contrast the e-biker doing 20 miles on a 0.4 kWh charge is doing 50 miles per KWh. (Very little of which is wasted)
In order for the above to be a fair comparison we need to take into account that there have been considerable losses in the electricity supply before it reaches our battery, 45% probably being a typical overall efficiency figure for the generation and supply network which reduces the bikes miles per kWh figure to about 22, but still twice that of the bus.
I think the average occupancy of the bus may well be less than 30 passengers taking into account the empty trips to and from the depot and the off peak times when there may only be a handful of passengers, if this is the case then the bike has a greater advantage.
In the case of commuter trains and trams public transport may well be more efficient than our e-bike, at least at times when passenger numbers are high. Express trains however cannot compete with our bikes on efficiency alone, but few of us would consider using a bike for that kind of journey anyway.