Initial rough concept of my tyre changing tool
Bottom handle hooks over the edge of the rim, and the hook slides down between the side wall of the tyre and the rim hooking under the bead of the tyre. The handles are squeezed together, and then, once the bead is above the rim the handles of the tool are canted down towards the wheel hub so as to bring the bead accross to the outside of the rim. Once this is done, the handles are slowly released, and the tool is moved to the next position.
Remounting the tyre is a reverse of the above procedure.
The tyre comes off the rim in the same way as using tyre levers, but because most of the work is done when squeezing the handles together, the chance of injuring hands etc on the wheel is practically eliminated.
This tool will be alot kinder to the inner tube compared to the tyre levers as the hook only needs to get underneath the bead rather than going all the way behind it as happens when using tyre levers, thus greatly reducing the risk of pinching the tube.
Still to be added is a ratchet mechanism on the tool to allow the first tool to be held closed if needed.