Finding a bike inner tube in Germany when shops are shut or just a bike shop

When we are touring we always try to set off with at least one spare inner tube per bike. If we have more than two punctures we try to buy another tube. Murphy's Law will then come into play and the odds are that we'll need a spare inner tube once shops have shut. However the well organised Germans have a cure for this. Many German bike shops have Schlauchautomaten (bicycle inner tube dispensers) similar to cigarette machines but healthier, fitted on an outside wall. The next question then arises where do we find a bike shop? Schwalbe, the German tyre and inner company has supplied our local bike shop with signposts so that strangers can find their way to the shop and the inner tube dispenser. These signs can also be used to find a bike if your bike needs  repairing. A good idea and an excellent bike shop.