Wow, that's pretty darn light! Does anyone have an idea how much the stock swingarm weighs? Is there a bearing where the swing arm connects to the frame?
I guess for calculating the force, it seems like the biggest force is the impact from jumping it. How many feet vertical drop could that swingarm withstand?
For a 220-pound rider, plus the 110-pound bike, I calculate that if landed completely on the back wheel from a 9.8-foot drop (3 meters), the swing arm would be subjected to 3,246 foot-pounds. I am guessing the lateral forces for centrifugal force, handling, etc. should probably be, what a half or a quarter of that?
Now, I am considerably lighter than 220 pounds, and never jump more than a couple feet, but that seems like a pretty good design goal. What do others think? How many vertical foot drop should a swingarm be able to take, with how heavy of a rider? What do you think the Sur-Ron was designed for?