How do different Roundings affect the Poll Pressure from a Pelham?

Curb bits are meant to be used with two reins, but often you will see a rounding, or a connector, between the snaffle and curb ring used with a singular rein.

We have done some basic pressure testing of three different roundings with a Pelham to see what effect they have on poll pressure. They were all recorded with about 4kg of rein pressure pulling from the same direction.

Snaffle Rein Only

When the Snaffle rein only is engaged, no additional poll pressure is recorded. This is to be expected as the Snaffle rein has no leverage

Leverage Rein Only

The leverage rein on its own created 1.5lbs of additional poll pressure.

Rounding 1: Connector with central ring

This rounding, or connector, that connects both the snaffle and rein together to a separate ring, created 1.3lbs of additional poll pressure. This is with both parts set to equal length. So, the level of poll pressure drops slightly when using this rounding but only by a small amount.

Rounding 2: Long Rounding

Then we had a long rounding where the rein can slide up and down, which created an additional 0.7lbs of poll pressure. So just less than half the poll pressure of the leverage rein only. Likely because the rein can slide up this rounding and promote the snaffle action a little more.

Rounding 3: Short Rounding

And finally, a short rounding where the rein can still slide a little bit - this created an additional 0.9lbs of poll pressure. So a little more than the long rounding, but still far less than the leverage rein on its own, or the connector with a fixed ring.

Though these exact pressure amounts may vary slightly when used with a real horse, they can be extrapolated to prove that the rounding that you use can affect the mechanics of the bit and the additional pressure felt.