I agree with everything about the weather. June/July is very friendly weather, especially for bikers (usually almost no rain for most of the summer). April could be rainy and not so warm. Logarska valley is besides Triglav valley probably the most beautiful place in Slovenia. And if you will go to Triglav national park and that part of Slovenia you should visit (if you have time):
As you can see, there is a lot to do just in Triglav national park. I advise you to visit
THIS web page for more other info.