Variable magnetic resistance unit for an exercise device

A bicycle training apparatus comprising:

• a) a support frame adapted to support a bicycle having at least one wheel;
• and
• b) a resistance unit attached to the support frame, wherein the resistance unit includes a roller engageable with a bicycle wheel, a shaft extending outwardly from the roller an electrically conductive member, and a rotatable member attached to the shaft and located adjacent the rotatable member, the rotatable member having a radially outwardly movable magnetic element that interacts with the electrically conductive member to establish a resistive eddy current force upon rotation of the rotatable member, wherein the magnetic member is radially movable in response to the speed of rotation of the rotatable member caused by rotation of the bicycle wheel to resist rotation of the bicycle wheel.

A method for providing resistance to a bicycle wheel rotatably secured to a bicycle trainer, the method comprising the steps of:

• a) providing a bicycle trainer having a wheel engaging assembly and a resistance unit, the resistance unit including an electrically conductive member, a shaft connected to a wheel-engaging roller and to a rotatable member, the rotatable member including at least one support, the at least one support having at least one slidable magnetic element urged radially inwardly by a biasing member;
• b) engaging the wheel with the roller such that the wheel rotatably contacts the roller;
• c) rotating the wheel to rotate the roller, shaft and rotatable member, wherein the magnetic element interacts with the conductive member to establish an eddy current force that resists rotation of the rotatable member and thereby the bicycle wheel, wherein radial movement of the magnetic element in response to variations in the speed of rotation of the rotatable member functions to vary the radial position of the eddy current force to vary the degree of resistance to rotation of the rotatable member.

In a magnetic resistance unit for an exercise device, wherein the magnetic resistance unit includes a rotatable member rotatable about an axis of rotation, the improvement comprising a variable position magnetic arrangement that is operable to establish an eddy current resistive force which resists rotation of the rotatable member, wherein the variable position magnetic arrangement is operable to vary the strength of the eddy current resistive force in response to the speed of rotation of the rotatable member.