When travelling by motorcycle in Germany you must always carry:
A full, valid driving licence.
Proof of insurance (third party or above)
Green Card
Proof of ID (Passport)
Proof of vehicle ownership (V5C Certificate)
GB Sticker, if you don’t have a GB EU number plate.
Speeds:
Urban limits are 50km/h (~30mph), within those areas there will often be 30km/h (~20mph) limits in residential areas or near schools etc.
Outside urban areas the national speed limit on normal A-roads is 100km/h (~60mph)
There is no speed limit in general on the German motorways (Autobahn), but on half of them the speed is reduced depending on road condition, traffic etc. There is an advisory limit of 130km/h (~80mph).
Lane splitting – cutting between lines of moving traffic – is forbidden and car drivers may close the gap.
You are legally bound to leave a gap (Rettungsgasse) for the emergency services in case of a traffic jam
Taken of these Websites:
https://www.bennetts.co.uk/bikesocial/news-and-views/features/travel/how-to-ride-in-germany-speed-limits-documents-the-law
https://www.lazymotorbike.eu/riding/germany/#rules
https://www.lexhaminsurance.co.uk/blog/10-best-motorcycle-tours-of-europe/
https://www.adac.de/reise-freizeit/reisen-motorrad-oldtimer/motorradtouren/deutschland/