14/07/2023
I have just seen a post from a bitting expert who suggested that you use fulmer keepers on a full cheek bit.
Please don't.
The orientation of the bit in the horse's mouth alters when we take the slack out of the rein. They rotate around their bore axis from the initial angle into the working angle. The direction of rotation differs between a loose ring and a fixed ring bit.
A fulmer bit is a modified loose ring bit with elongated sides which act against the horse's lips. Because it is a loose ring bit it will rotated clockwise (when viewed from the near side) into it's working angle taking any tension off the fulmer keeper.
The keeper is used to stabilise the sides without having any effect on the designed action of the bit.
A full cheek bit is a fixed ring bit and will rotate anticlockwise into it's working angle when the slack is taken out of the rein. Adding a fulmer keeper to this bit will alter the action of the bit, creating poll pressure and potentially block rotation. This is particularly significant for bits designed to offer the smoothest profile to the horse's mouth when they rotate into their working angle, for example the NS tranz angle lozenge.
Below fulmer on left, full cheek on right