The structure of a big and small wheel folding bike

Functions:
Volume is reduced by almost half; removable folding, but driving speed is as same as the general bike.
Climbing because the center of gravity moved backward easily than normal bike. A small radius of rotation, thus even at small space, it still turns flexibly.

Usage:
Can easily be placed in the cars back;  portably, easily take it upstairs and out of the elevator, no need to fold, it’s quite  convenient.  The important is it doesn’t affect the other people out of the elevator. Since it is accessible; it also no needed to park at outside, directly bring it into house. Thus don’t worry it will be stolen or damaged by bad weather.

Specifications:
The former wheel is 12 inches and back big wheel is 24 inches. The handle can be folded up and down to adjust the height. Installation of variable speed teeth wheel, driving is more convenient.
Car length:115 cm
Seat height:82 to 87 cm
Handle height:
112 to 122 cm
Brake: Disc brakes
Rear derailleur:
shimano transmission