I’ve often wondered the same thing. I’m 210 when naked (sorry for the visual :eek: ) and have had my share of hard landings, not necessarily from 85’ doubles though.
The shear stress of the pin that the peg pivots on is probably the weakest link and all foot peg designs are not equal but a ball park stress value for the pin with a 4G load (4 times your body weight) from a 200 lb rider is roughly 25,000 psi. with a 3/8 dia pin. That may sound high but I assumed all the load was taken by one peg and I don’t know if 4Gs is realistic.
The shear strength for the pin is the question. I don’t know what material they use but shear is generally half the yield strength . For, let’s say a hot drawn 1050 steel, which has a yield of 49,000 psi, the shear would be roughly 25,000 psi. That means that with a 4g hit on one peg by a 200 lb rider, the pin would start to yield (permanently deform). A weaker material, like a grade 5 bolt, would probably break.
Bottom line is you’re probably safe so long as the pin, foot peg, and frame are in good shape. When you replace he pin, make sure its an OEM part and not some bolt you find laying around. As the pin wears, the cross section is reduced and the overall strength is compromised so make sure it’s OK.
Disclaimer: The numbers above were quickly calculated and I won’t swear to their accuracy but they are in the ball park. I just don’t want to get blasted for any liberties that I may have taken. If anyone does know the typical g-force from a landing and the actual material that is used for the peg pivot pin, I can do a more complete analysis.