The French Crossed Carabiner method only requires two carabiners, and it does not introduce a twist in the rope. It is simple to rig, but the rappeller should be aware of a potential nasty surprise if the top carabiner gets hung up and there is not enough tension from the braking hand to keep the two carabiners from separating: if this happens, you are suddenly rappelling on a 3:1 pulley system. When things are going smoothly the carabiners do not ride on each other’s gates, but if any slack is introduced, the carabiners can shift, and either link or break.

Warning: Don't try this system without a belay.

The chain can be extended to give more friction, but this also increases the chance of the top carabiner hanging up. I don't recommend doing this, since the whole setup may become unstable. A better way to increase the friction is to add a twist around the lower carabiner. This will impart some spin, but since this is at the low-tension end of the rope, it won't be as bad as a straight Ranger arrangement.