Harz routes, courtesy of Harz Point website
If you hunt around it’s possible to find something, though I think it’s just an extract from the original site as it seems to only deal with the West Harz. ‘Die Touren sind von Harz Point entwickelt worden‘ translates via Google Translate to: The tours have been developed by Harz Point. But hey, it’s better than nothing.
https://www.oberharz.de/fileadmin/media/Downloads/Flyer-Prospekte/Bikerflyer_Oberharz2018.pdf
Zoomed in a bit:
Found from this site:
https://www.oberharz.de/start-sommer/
Then putting ‘Motorrad’ into the site’s search box.
The full blurb on each route says:
Tour suggestions for motorcyclists
Feierabendrunde Harz West 1:
Route: You start in Clausthal-Zellerfeld and drive via Goslar and Oker to Okerstausee, past Altenau and Torfhaus. Afterwards, the route will take you via Sonnenburg and Dammhaus back to Clausthal-Zellerfeld.
Length: 65 km
Duration: about 1 hour
Feierabendrunde Harz West 2:
Route: You start in Clausthal-Zellerfeld. The route takes you via Bockwiese to Lautenthal. Continue on Wildemann and Bad Grund, past Gittelde and Badenhausen, to Osterode. From here you drive past the Sösestausee, via Dammhaus, back to Clausthal-Zellerfeld.
Length: 70 km
Duration: about 1 hour, 15 minutes
Day Tour West Harz:
Route: The winding route starts at the Innerste reservoir and then leads via Seesen, Bad Grund, Wildemann, Lautenthal and Bockwiese to Goslar. Continue on the Okerstausee, Altenau, Dammhaus and Sösestausee over to Osterode. Then it continues via Herzberg, Silberhütte, Odertal to Oderhaus. From here you can make a detour via Braunlage, Hohengeiß, Zorge, Wieda and back to Oderhaus. Or you drive directly from Oderhaus via Sankt Andreasberg, Sonnenberg and Torfhaus to Bad Harzburg.
Length: 250 km
Duration: approx. 4 hours, 30 minutes
As an added bonus, here’s a guide to those all important biker friendly hotels, without which no tour, bimble, hoon or Adventure (with a capital A) is complete. Guard your ‘Pride and joy’....
https://www.mein-tourenhotel.de/hotels_for_your_motorcycle_tour_in_harz