To add a data point: I cycle to work daily (22km) and have cycled pretty much all my life since. Sustaining 40km/h for longer periods is unrealistic if 1.) you

To add a data point: I cycle to work daily (22km) and have cycled pretty much all my life since. Sustaining 40km/h for longer periods is unrealistic if 1.) your terrain is not completely flat; 2.) there is wind; 3.) you do not want to get to your destination soaked with sweat; 4.) you have to carry some luggage like a laptop; or 5.) you cannot use a touring bike because of the terrain. I sometimes cycle with a GPS and have Pedelecs (limited to 25km/h for electrical support in Germany) as a reference point. The vast majority of cyclers that I encounter cycle less than 25km/h under normal conditions [1]. Probably somewhere between 20 and 25. If there is strong wind or uphill, it's definitely less than that.