You can only ride the road that you can see, so if you’re on an unknown road, your pace is going to reduce slightly. That doesn’t mean that you have to crawl along though.
Make the most of your lane, move across to the white line when approaching left-handers. It will open up your view of the corner.
If the road is tightening up, scrub speed off, if it’s opening out, add speed. Simple.
If the road is tree-lined, have a look ahead at the direction and flow of the trees. If they suddenly veer off at 90 degrees, you’re probably approaching a junction or a tight corner and need to ride accordingly.
The same rule of thumb applies to telegraph poles; they usually track the same path as the road that you are on. Don’t be surprised if you can’t maintain the speed limit and don’t use it as a minimum requirement.
Remember, ideally you should be able to safely stop within the distance of the road that you can see in front of you.
Have fun and stay within your limits.