Re: Panama jack failure!!!!!!
Yep, Rustycase is right, it's pretty hard to top a quality steel frame. I've owned aluminum alloy bikes (back before I was motorizing) and it's good with the right temper, but it is a totally different metal from steel. Most kinds of aluminum don't well tolerate much flexing, vibration, or shock for long periods of time. There are some higher-end aluminum frames which seem to have tolerated being motorized, but I can't recall which ones; maybe their owners will chime in here.
And don't get me started about carbon-fiber frames. Major temperature variances can cause expansion/contraction-related size differences between the carbon-fiber and metal parts. On a chilly day, you have a real rattle trap. What a motor would do to that, I have no clue. They are designed for, and best left to, pedal power I think.
Modern high-quality steel is a technological marvel. It's been done and proved good for the application. Most of us here already know which steel frames we can trust the most. And although the cheap-steel Panama Jack frames have caused documented breakage failures, even many other inexpensive steel frames have proved usable. Ask around the forum. There are guys here who jump at the chance to brag on their bike frames.
"There is nothing wrong with wanting a motorbike that is an extension of your personal taste and fashion sense; if you must ride somewhere, I say do it with style