Schlettichweg Trail

This is a great alternative to the paved bike path between Unterhof and Zuzenhausen / Meckesheim, which afterwards turns into the forest path anyway or leads over the mountain near Oberhof.
There is nature, shade and, above all, no cars, the trail is also not demanding, but nice to drive and therefore suitable for all types of bike.
Overall, the route leads completely through the forest, the gradients are all moderate and can be mastered by everyone.
PS: I've already ridden it on my racing bike, but I would say that the very narrow racing bike tires are actually not suitable, as S. Fischer writes. But the trend is also more towards tires up to 32-35 mm wide, with which it works without any problems.

pleasant forest road for almost all types of bikes
not suitable for racing bikes

There are several alternatives between Dielheim and Meckesheim, but none are official and you have to go over the mountain everywhere.
The best alternative in dry weather is the Schlettichweg. The entrance is at the forest car park in Oberhof. Follow the signs at the junctions. The route is also signposted from Meckesheim.
After the upper section on Keidelsbruchweg has been paved, the downhill ride has become safer, even for inexperienced bikers.
In wet weather I prefer the route at the fish pond.