Originally Posted by tsujinago
As a 17 year old, I can't find disagreement in any of you guys' statements in terms of safety but a small series of little bloopers with motorized bicycles and everything about their assembly and maintenance has been a major factor in myself growing an appreciation for getting things done the right way, regardless of actual mechanical aptitude.
That said, there's a certain threshold where keeping up with traffic speeds might just be safer than trundling alongside the road at 20mph, out where roads have little more than a foot of shoulder and people fly over hills and all. Therefore, I do believe that riding style and respect for road rules has more bearing on safety than how fast your bike goes (if it's built to handle it, that is).
The idea of "keeping up with traffic" means you are traffic and places oneself under the purview of just another class of motor vehicle subject to all DMV and DOT regs of any other motor vehicle on the road.
There are potentially as many reasons and rationalizations as there are individuals looking for loopholes on how to slip through the legal cracks sideways into two wheeled motorsport without paying the freight but LEOs and state legislatures aren't that stupid and eventually will come back to bite ya. IMO, keep it low power, keep it a bicycle with low power assist and it'll be a lot easier explaining why it shouldn't be regulated as just another motor vehicle.