Longer straps for riders with big jowls
Summary: Riders sometimes have such large jowls that there is not enough extra strap length for the chin strap to buckle. We don't have a good solution for that except to look for a helmet with longer straps.
Some helmet programs have had difficulty finding helmets with long enough straps for children who are severely obese and have extraordinarily large jowls. Even extra-large adult helmets do not have enough strap length for the buckle to fasten.
There are reasons why you would not want to use a strap extension. The two buckle pieces have to mate. Many of the buckles look exactly the same, but in fact there are variations you can't identify by sight. You could not use half of a buckle from another source, or even another batch, and expect it to meet the CPSC strap strength standard. You can't sew a length of strap on to extend the chin strap either, since sewing a strap is not simple and the long term strength of the stitches cannot be determined as they age and are affected by sweat or sunlight. Even an extension with buckles would run the risk of not mating the correct buckle with the correct strap material, another source of lab test failures.
At this point our only advice is to look for a helmet with longer straps. We do not have one to suggest, so if you find one, please email us about it so we can post it here.