Originally Posted by BigAura

For pretty much any bicycle, especially an LHT, to have uncontrollable shimmy it has to very damaged or horribly built.

The shimmy you experienced was most likely induced by your own muscles. It takes a time for a persons body to adjust to different bicycle especially a load one. This adjust may take a few seconds for an experienced rider or an hour for someone without experience. I know I've even experienced a shimmy when after riding a fully loaded bicycle all day and then unloading it. The first few seconds my muscles over-under-steering rapidly. This is the type of shimmy you most likely experienced.