Just don't tie it down in front using the handlebars. Ships sink, airplanes crash, and handlebars will slip. When they do, you have an 800+ lb. weight slamming back and forth in the trailer. My neighbor argued the point with me a couple years back, said he had tied his HD down for years using the handlebars with nary a problem. I told him that's fine, but it only takes one time(and a lot of money) to make a believer out of a person. He is now a believer. He was headed north to visit some family and had it tied down in his nice three yr. old GMC. Hit some road repair that was rough somewhere in N. Carolina and the bars slipped down less than a half inch at the grips. Tore up the bike real good, also messed up the sides of his p/u pretty good as well. We don't talk about it now, but he was one meek dude for a couple months.
Hi John... you don't know where he attached the hook to the handlebar, do you? There would
be a lot of leverage to make the bars slip unless you put the hooks right on each side
of the risers, there's no leverage there...
Sometimes it is hard to find a "not the handlebars" place to hook on the tie downs... Ancra
makes these things to help... strong, and no metal hook to touch your bike..

-Mike