fauxpas said:
So my question is, I have read many posts about how many kilometres per ride for training etc, but 20k for me may be a different 20k for you as the roads are not identical... So when someone refers to riding 20k, do we take for granted a 20k flat road?
faux
Assuming a flat road, little wind, and riding at decent pace (not loafing, but not going as fast as possible either, about what it takes to work up a good sweat) I would be riding at about 30 km/hr. You might ride faster or slower under the same conditions at the same level of effort.
Now, if due to hills or winds you are working harder and going slower, you would consider a 20 km ride to be longer than 20 km, because it would take you so much longer to ride it. So, figure a "20 km ride" to be equivalent to saying "riding at a good pace for 40 mins". If someone says they rode a certain distance I think it is assumed the conditions were reasonably flat or rolling, unless they specify they were hilly.
It is really hard to give a "good" average speed, because speed depends so much on wind, hills, your bike (type of bike, weight, tires), the distance you are riding, and the type/class of rider you are comparing yourself to etc...
For someone interested in fitness and distance riding, under 25 km/hr is on the slow side (below 20 is definitely slow), 25-35 is moderate, and faster than 35 is fast. These are just my own estimates assuming the relatively flat road with not much wind. Hills or a headwind can cut your speed dramatically. I might ride 30 km/hr no wind, while 20 km/hr into the wind, and +35 km/hr with a tail wind.