Aerodynamic fork mast structure
View Patent ↗A front fork for a bicycle having an upwardly extending mast of an aerodynamic teardrop shape to which a handlebar may readily be attached.
1. A front fork member for a bicycle having a pair of fork arms, a fork head and a mast,
the fork head having a lower end and an upper end,
the fork head carrying a journal mechanism between its lower end and its upper end for complementary engagement with a bicycle frame for relative pivoting of the fork member to the frame about a pivot axis,
the fork head symmetrical about a central plane including the pivot axis,
each fork arm joined to the lower end of the fork head and extending downwardly to a distal end,
the fork arms spaced laterally from each other about the central plane and adapted to receive a wheel therebetween below the fork head journalled for rotation about an axis normal the central plane,
a mast extending upwardly from the upper end of the fork head and forwardly about a straight mast axis disposed in the central plane at an angle to the pivot axis, the mast symmetrical about the central plane,
the mast having an external surface having, in any cross section normal to the mast axis, a mast teardrop shape having an enlarged rounded forward end and a reduced size rear end, the mast teardrop shape being substantially identical in shape and size in any cross section through the mast normal to the mast axis.
2. A front fork member as claimed in claim 1 in combination with a handlebar member, the handle bar member having a mounting bracket for securing the handle bar member to the mast to couple the handle bar to the front fork,
the mounting bracket having a bore there through with interior surfaces disposed about a straight bore axis,
in any cross section normal to the bore axis the interior surfaces forming a bore teardrop shape having an enlarged rounded forward end and a reduced size rear end, the bore teardrop shape being substantially identical in shape and size in any cross section through the mounting bracket normal to the bore axis,
the bore teardrop shape being complementarily shaped and sized to the mast tear drop shape such that mast is removably slidably received in the bore with engagement between the exterior surfaces and the interior surfaces maintaining the mast axis parallel to the bore axis and the mounting bracket prevented from rotation relative the mast about the mast axis,
a fixation mechanism for fixedly coupling the mounting bracket to the mast at any one of a plurality of desired relative positions along the mast when the mast is received through the bore.
3. The combination claimed in claim 2 wherein the height of the handlebar member is adjustable by sliding the bracket member longitudionally along the mast with upward sliding of the handlebar moving handlebar member forwardly and rearward sliding of the handlebar moving handlebar member rearwardly.
4. The combination claimed in claim 2 wherein the mounting bracket comprises a pinch clamp.
5. The combination as claimed in claim 2 wherein the journal mechanism having an uppermost portion of the fork head comprises a journal tube member fixed to the remainder of the fork head against relative movement or rotation, the journal tube member having generally cylindrical exterior bearing surfaces disposed coaxially about the pivot axis and adapted to extend coaxially upwardly through a journaling bore on the frame for the bicycle,
an upper end of the journal tube member removably fixedly secured to the mast against relative movement and rotation within an internal socket in the mast extending upwardly in the mast from a lower end thereof internally of the exterior surface of the mast.
6. The combination as claimed in claim 2 wherein as the journal mechanism an uppermost portion of the fork head comprises first half of a hinge structure adapted to be coupled to a second complementary half of a hinge structure carried by a bicycle frame.
7. The combination as claimed in claim 6 wherein the first half of the hinge structure is coupled to the second half by a hinge pin member extending coaxially of the pivot axis.
8. The combination as claimed in claim 2 wherein a cap member is removably secured to an upper end of the mast above the mounting bracket, the cap member having teardrop shape being complementarily shaped to the mast tear drop shape symmetrical about the central plane,
having an enlarged rounded forward end and a reduced size rear end.
9. A front fork member as claimed in claim 1 in combination with a handlebar member, wherein:
the mast having an internal mast bore extending from an upper end of the mast into the interior of the mast,
the handle bar member having a mounting plug to be received internally within the mast bore.
10. The combination as claimed in claim 9 wherein the mast bore extends parallel to the mast axis and is of a uniform shape and size in cross section normal to the mast axis.
11. The combination as claimed in claim 10 wherein the mounting plug is slidable within the mast bore parallel the mast axis for attachment and removal.
12. The combination as claimed in claim 11 wherein the mast bore and the mounting plug have complementary shapes which are asymmetrical relative the mast axis such that the mast bore engages the mounting plug against relative rotation.
13. The combination as claimed in claim 11 wherein the mast comprises a hollow tubular member.
14. The combination as claimed in claim 13 wherein the mast is adapted to be cut in a cross section normal to the mast axis to adjust the height of the upper end of the mast and thereby the height at which the handlebar member is located on the mast by insertion of the mounting plug into the mast bore.
15. The combination as claimed in claim 14 wherein the mast bore has a teardrop shape having an enlarged rounded forward end and a reduced size rear end similar to the tear drop shape of the external surface of the mast.
16. The combination as claimed in claim 9 including a fixation mechanism for fixedly coupling the mounting plug in the mast bore.
17. A front fork member as claimed in claim 1 in combination with a handlebar member, the handle bar member having a mounting device for securing the handle bar member to the mast to couple the handle bar to the front fork,
the mounting device engaging exterior surfaces and/or interior surfaces of the mast to prevent relative rotation of the handlebar member relative the mast.