If we buy two new bikes then at least two old ones have to go.

As ever there is an additional problem. We have nine bicycles sitting in our cellar and in the cupboard in the hall: 

• Three "Bahnhof's bicycles" we can leave at the tram station in the town and be sure that there are more attractive bikes about in the bike parking area at the tram station. 
• Two Dahon tourers.
• Two mountain bikes.
• Two Bromptons.

The first five would be favourites to pass on, but of the two Bahnhof's bikes one is a historic Peugeot Cologne tourer and the other is the first bike that Judith ever bought new. In both cases it would be like putting down a family pet.
The Bromptons are in use most days of the week. 
It looks like the Dahons would be favourites. One of the Bahnhof bikes can be donated or flogged off for €20.
I suspect we will leave things as they are for while and not buy new bikes.