Folding bicycles often separate or fold in the middle of the frame, which, depending on the design, can weaken the frame and cause more energy-absorbing flexing. Many have elongated seatposts and stems. These longer components, which project above the frame like masts, experience greater bending stresses where they meet the frame, compared to the shorter components of regular bikes. There have been sporadic reports of failure in these components in online message forums[citation needed], and at least one recall due the failure of the steering mechanism.[citation needed] Folding bicycles necessarily have more parts, to allow folding and to lock the frame when unfolded. This results in a more complicated design, with more parts that can potentially fail.

The A-bike is similar to the Strida but has tiny wheels and compacts a bit smaller. Bikes smaller than a Brompton are often called portable bicycles. They forgo the performance and easy ride benefits of their larger counterparts, acquiring characteristics similar to those of an adult folding kick scooter. Regardless of how each folds, the result is easier to transport and store than a traditional bicycle.

http://www.greenzonebikes.com/foldingtandem-bicycles.html