I made a shocking discovery recently - old roads are not like new roads.
I'm not referring to the quality of the road surface - I'm talking about how they were constructed.
In the old days, when the country as a whole was not as rich as it is today, roads were built over or around things. If there was a hill, the road went up one side of the hill and down the other. They just scraped off the top layer of dirt, put down a foundation and plopped tar on top.
Fifty years later, a richer country builds roads differently. If there is a big hill in the way, in come the bulldozers and a chunk of the road is removed to reduce the gradient. If there is a valley, it's either filled in or bridged.
This becomes pretty bloody obvious when cycling because if you have an old road and a new road running through the same countryside, one will murder your legs and lungs and the other will be a breeze. Gradients count for a lot when you provide all the motive power.
The legs of course want me to stick to new roads. However, the training part of my brain says I have to mix in some older roads in order to bash the crap out of my muscles. It can be hard work balancing out the desires of the two body parts. Half a ride can be taken up with the decision making process regarding which road to take when that certain intersection is reached.
If nothing else, it gives you something to think about.