MGAGB will be using the new IMGA rule in 2018.
The rule for 2018 will be:
GR2.4. The size, weight and experience of a rider must correspond to the size, build and experience of the pony. If the referee deems a rider to be overweight or unsafe, that rider will be eliminated from the competition. A rider is overweight for a pony if the rider’s weight exceeds 20% of the pony’s bodyweight.
This is similar to the height weight graphs, although some light built ponies can carry less than the graphs and some strong ponies much more.
Anyone who wants to work out their pony’s weight could use the following (please note there will be an app available in a few weeks to help you calculate it)>