Extract from the article: Choosing a bike for the City
The folding bike.
The folding is a separate bicycle. It's a minimalist bike that meets an additional need: to be easily transported without anyone on it. Thus the folding bike is justified if you make part of your journey by train or by car. For example, you can park your car at the entrance of a city and finish by bike. The folding bicycle is quite rare and the purchase often has to be new. An elementary bike (low quality, single speed ...) will be inexpensive (easily counted 80 to 100 €). There are however some very good folding bikes that fold in several points, with a good range of speed and powerful brakes. On the other hand, the prices can go up very quickly (up to 1000 € without forcing!). Choose a folding with wheels for which you can easily find tires and tubes. Avoid too exotic dimensions! Your interview will be even easier.
Finally, the folding bike is probably the only "urban" bike that is difficult to draw the portrait robot because there is a multitude of models without really common frame equipment. Be careful in the choice and take your time: the best is the worst.

Folding bikes are hard to find cheaply. Always prefer models with equipment for which you will easily find spare parts (brakes, tires, etc.).