The sound the engines make, reverberating off the steep stony walls of the narrow valley, always seems in sharp contrast to the quiet, relaxed atmosphere of Shabbat.
Religious Jews do not drive on Shabbat and many non-religious stay around home to rest. Public transportation does not run either. So the bikers pretty much have the road to themselves.
BTW, in Israel we do not have Sunday off. Sunday is just the first day of the work week.
I haven't heard them much this autumn. But today is (and all week was) unseasonably warm, a sunny 24 C or 75 F, and the bikers are out in full force to feel the sun and wind on their face.