Bad Service
After some admittedly good advice from the manufacturer, I decided to buy the Rennstahl 853 PI Gravel bike. The bicycle itself is perfectly fine and of good quality.
However, that's where the positive points end. The manufacturer has neither good service nor does it respond appropriately to warranty claims. You can't expect proactive communication about shipping or similar matters. You should also be aware that every bike configured via the website (even without special requests) is immediately considered "individual" and, according to the manufacturer's terms and conditions, is specially made. Therefore, returns, etc., are excluded.
Furthermore, the manufacturer did not honor stated discounts and, upon inquiry, simply increased the price of the bike instead.
Additionally, the company headquarters are allegedly in Greece, and there is supposedly a showroom in Germany. Neither of these can be found on Google Maps or OpenStreetMap.
I cannot recommend the manufacturer and would strongly advise against buying anything from them.