[mnw21cam]

V_r is almost always above V_1, which is the decision speed. If you're going to abort a takeoff, that decision needs to be made before V_1, otherwise you're likely to overrun the end of the runway.

So, once you get to the stage where you're ready to rotate, or even late in rotating, you're committed to getting the plane off the ground.

[wkat4242]

On a big airliner yes. V1 depends on the runway length so a smaller aircraft will easily reach Vr before V1. Because most runways are made for the biggest planes.