The present invention relates to a fixture for the assembly and disassembly of special gears, said fixture being more specifically meant in particular for the assembly and disassembly of gears of free-wheels applied to the rear wheel of bicycles from the free-wheel unit of which they form part.
It is known that a free-wheel unit for bicycles comprises two coaxial bodies, of which the outermost body is apt to roll over the inner one, and a plurality of chain gears (generally four, five or six, according to the type and use of the bicycle), of which one part is keyed, and the last one or two are screwed, onto the outer body of the unit.
It is also known that in sports bicycles in general, but especially in competition bicycles, it is often necessary to replace the gears forming the free-wheel unit, by means of which gears one controls--through the gearshift--the rotation of the rear wheel by acting on the pedals. These operations of replacing the gears become particularly important when they have to be carried out during cycling races--as for example, in particular, the Tour of Italy and the Tour of France--in which it is often necessary to replace the ratios of all the bicycles of the team at each goal, in order to adapt the bicycle itself to the characteristics of the courses being followed which can vary, even considerably, every day. One can hence understand the importance of being able to replace the gears of the free-wheel units promptly and easily.
Up to date, the possibility to carry out the above operation of replacement promptly and easily has just been wishful thinking in the mind of the skilled in the art, who have been forced to perform said operation with makeshifts (making the work toilsome, long and often inaccurate, and at times causing damage to the parts involved) or with complicated, bulky tools of difficult use.