The road looks white because the trees are shedding some dandelion-like seeds.
Imagine a road carpeted with a thick layer of this:
As we rode through, it swirled up behind the bikes in eddies, and it was falling all around us. Like snow.
At this point, a father with his two children that we had passed about twenty minutes earlier caught up with us and rolled by. There was an older son and younger sister - maybe 14 and 12. When we caught up with them again, we talked for a little bit. They were on their way to a lake for a few days holiday. The dad had planned to do the 100+ km over two days, but the kids persuaded him to try to do the full 100+ km in one day. We noticed that on the hills, the daughter grabbed the edge of the bicycle trailer the dad was pulling for a little assist. Yet another cool cycling family. I love how the kids are so proactive (recall the father with his two very young daughters in Staad, Switzerland - they were the ones who begged him for the trip).