Folding bicycle

1. A folding bicycle ( 1 ) having

a frame ( 2 ) which extends in a main extension plane ( 24 ),

a front wheel ( 53 ) which is pivotable about a first axis ( 56 ) extending perpendicularly to the main extension plane ( 24 ),

a rear wheel ( 16 ) which is pivotable about a second axis ( 23 ) extending perpendicularly to the main extension plane ( 24 ), wherein the frame ( 2 ) has an articulation ( 37 ) such that the front and rear wheels ( 53 , 16 ) are pivotable with respect to one another about a third axis ( 41 ) extending perpendicularly to a roadway ( 42 ), and

a headset bearing ( 43 ) by means of which the front wheel ( 53 ) is mounted in a rotatable manner about a fourth axis ( 45 ) in order to steer the folding bicycle ( 1 ), wherein, in order to adjust the folding bicycle ( 1 ) between a riding position and a transporting position thereof, the front wheel ( 53 ) is pivotable in opposite directions about the third axis ( 41 ) and the fourth axis ( 45 ).

2. The folding bicycle as claimed in claim 1 , wherein the frame ( 2 ) has a headset bearing ( 43 ) by means of which the front wheel ( 53 ) is rotatably mounted in order to steer the folding bicycle ( 1 ), and a seatpost bearing ( 6 ) which supports a seatpost ( 35 ), wherein the articulation ( 37 ) is arranged centrally in a direction of travel ( 82 ) between the headset bearing ( 43 ) and the seatpost bearing ( 6 ).

3. The folding bicycle as claimed in claim 2 , which is adjustable between a riding position and a transporting position, wherein the headset bearing ( 43 ) and the seatpost bearing ( 6 ) are arranged alongside one another in the transporting position.

4. The folding bicycle as claimed in claim 1 , wherein, in order to adjust the folding bicycle ( 1 ), the front wheel ( 53 ) is pivotable in a direction of travel ( 82 ) between a riding position and a transporting position of said folding bicycle ( 1 ).

5. The folding bicycle as claimed in claim 1 , wherein, in order to adjust the folding bicycle ( 1 ), the rear wheel ( 16 ) is pivotable in a direction of travel ( 82 ) between a riding position and a transporting position of said folding bicycle ( 1 ).

6. The folding bicycle as claimed in claim 1 , wherein, in order to adjust the folding bicycle ( 1 ) between a riding position and a transporting position thereof, the front wheel ( 53 ) is pivotable about the first axis ( 56 ) and the rear wheel ( 16 ) is pivotable about the second axis ( 23 ) in a same direction.

7. The folding bicycle as claimed in claim 1 , which is adjustable between a riding position and a transporting position, wherein, at least in the riding position, a rotation axis ( 92 ) of the front wheel ( 53 ) is located behind the first axis ( 56 ).

8. The folding bicycle as claimed in claim 1 , having a head tube ( 44 ) and a front wheel swing arm ( 55 ) which at its one end ( 60 ) is mounted pivotably on the head tube ( 44 ) and at its other end ( 91 ) supports the front wheel ( 53 ) in a rotatably mounted manner, wherein, in order to adjust the folding bicycle ( 1 ) between a riding position and a transporting position thereof, the front wheel swing arm ( 55 ) is pivotable between a first pivoted position, in which a rotation axis ( 92 ) of the front wheel ( 53 ) is arranged on one side of the head tube ( 44 ), and a second pivoted position, in which the rotation axis ( 92 ) of the front wheel ( 53 ) is arranged on the other side of the head tube ( 44 ).

9. The folding bicycle as claimed in claim 8 , having a fixing device ( 57 ) for fixing the front wheel swing arm ( 55 ) in at least one of: the first pivoted position or the second pivoted position.

10. The folding bicycle as claimed in claim 9 , wherein the fixing device ( 57 ) has a locking position, in which the front wheel ( 53 ) is prevented from pivoting between the first and second pivoted positions, and a releasing position in which the front wheel ( 53 ) is allowed to pivot between the first and second pivoted positions, wherein the folding bicycle ( 1 ) comprises a cable pull ( 86 ) by means of which the fixing device ( 57 ) is adjustable between the locking position and the releasing position.

11. The folding bicycle as claimed in claim 10 having at least one of:

(a) the cable pull ( 86 ) has a lever ( 87 ), arranged on a handlebar ( 51 ), for adjusting the fixing device ( 57 ) between the locking position and the releasing position; or

(b) the fixing device ( 57 ) has a detent disk ( 61 ) fastened to the front wheel swing arm ( 55 ), and a locking element ( 72 ) that is guided in a linear manner in or on the head tube ( 44 ) and is adjustable by means of the cable pull ( 86 ), said locking element ( 72 ) being in engagement with a detent ( 64 , 65 ) of the detent disk ( 61 ) in the locking position of the fixing device ( 57 ) and being disengaged from the detent ( 64 , 65 ) in the releasing position.

12. The folding bicycle as claimed in claim 11 , wherein the locking element ( 72 ) is secured against falling out by means of a bayonet closure ( 78 ) in the head tube ( 44 ) and the detent disk ( 61 ) prevents the locking element ( 72 ) from rotating in order to release the bayonet closure ( 78 ).

13. The folding bicycle as claimed in claim 1 , wherein, in order to adjust the folding bicycle ( 1 ) between the riding position and the transporting position thereof, the front wheel ( 53 ) is pivotable in a first step about the first axis ( 56 ) in the direction of travel ( 82 ), and the front wheel ( 53 ) is pivotable in a second step in opposite directions about the third and fourth axes ( 41 , 45 ).

14. The folding bicycle as claimed in claim 1 , which is adjustable between a riding position and a transporting position and has a head tube ( 44 ) and a front wheel swing arm ( 55 ) with two ends, wherein a first end ( 60 ) is mounted pivotably on the head tube ( 44 ) and a second end ( 91 ) which supports the front wheel ( 53 ) in a rotatably mounted manner, wherein the head tube ( 44 ) is cranked in the main extension plane ( 24 ) in the riding position of the folding bicycle ( 1 ) in order to leave room for at least one of: a pedal ( 17 ) or a bottom bracket cradle ( 11 ) of the folding bicycle ( 1 ) in the transporting position of the folding bicycle ( 1 ).

15. The folding bicycle as claimed in claim 1 , having a head tube ( 44 ), a front wheel swing arm ( 55 ) with two ends, and a spring ( 104 ); wherein a first end ( 60 ) of the front wheel swing arm is mounted pivotably on the head tube ( 44 ), a second end ( 91 ) supports the front wheel ( 53 ) in a rotatably mounted manner, and the front wheel swing arm ( 55 ) is supported on the head tube ( 44 ) by the spring ( 104 ).

16. The folding bicycle as claimed in claim 15 , having at least one of:

(a) a headset bearing ( 43 ) which holds the head tube ( 44 ) in a rotatably mounted manner with respect to the frame ( 2 ), wherein the spring ( 104 ) is arranged at least partially within at least one of: the head tube ( 44 ) or the headset bearing ( 43 ); or

(b) a strut ( 93 ) which is supported by the front wheel swing arm ( 55 ) and the spring ( 104 ), wherein provision is made of a coupling element ( 103 ) which acts against the spring ( 104 ) and has an insertion bevel ( 105 ) for receiving the strut ( 93 ).

17. The folding bicycle as claimed in claim 16 , having an elastomer compensating element ( 95 ), which connects the strut ( 93 ) to the front wheel swing arm ( 55 ) and allows the strut ( 93 ) to pivot with respect to the front wheel swing arm ( 55 ).

18. The folding bicycle as claimed in claim 1 , wherein, in order to adjust the folding bicycle ( 1 ) between the riding position and the transporting position thereof, the rear wheel ( 16 ) is pivotable in a first step about the second axis ( 23 ) in the direction of travel ( 82 ), the front wheel ( 53 ) is pivotable in a second step about the first axis ( 56 ) in the direction of travel ( 82 ), and the front wheel ( 53 ) is pivotable in a third step in opposite directions about the third and fourth axes ( 41 , 45 ).

19. A method for adjusting a folding bicycle ( 1 ) as claimed in claim 1 between a riding position and a transporting position thereof, wherein

the front wheel ( 53 ) is pivoted about the first axis ( 56 ),

the rear wheel ( 16 ) is pivoted about the second axis ( 23 ), and

the front wheel or rear wheel ( 53 , 16 ) is further pivoted about the third axis ( 41 ) relative to the other of the front wheel or the rear wheel.

20. The method as claimed in claim 19 , wherein, in order to adjust the folding bicycle ( 1 ) between the riding position and the transporting position thereof, the front wheel ( 53 ) is pivoted in a first step about the first axis ( 56 ) in a direction of travel ( 82 ), and the front wheel ( 53 ) is pivoted in a second step in opposite directions about the third and fourth axes ( 41 , 45 ).

21. The method as claimed in claim 19 , wherein, in order to adjust the folding bicycle ( 1 ) between the riding position and the transporting position thereof, the rear wheel ( 16 ) is pivoted in a first step about the second axis ( 23 ) in a direction of travel ( 82 ), the front wheel ( 53 ) is pivoted in a second step about the first axis ( 56 ) in the direction of travel ( 82 ), and, the front wheel ( 53 ) is pivoted in a third step in opposite directions about the third and fourth axes ( 41 , 45 ).