Re: Good kits that dont go over 30 mph 48km/h
Gear it low (large driven sprocket) and experiment with a mechanical throttle limiter.
I actually find no issue with the 30mph rule the OP is dealing with. It is a bicycle, not a motorcycle. It's been my experience that few builders will take the time or make the investment to upgrade critical components such as brakes, bearings, rims, spokes, etc to bring a bicycle up to the standards to make 30 plus mph safe. Yes, most of us do, but what about those who build without the advantage of the knowledge found on this forum? And guys, there are a lot of them out there.
I've seen bikes motorized by inexperienced and non-mechanical people that should have been limited to 15mph (or less) due to the lack of attention to even the most simple components or systems. It could very well be that the legislators are taking that situation into consideration when passing speed limit laws on motorized bicycles. Not everyone is capable of building a bike that would be safe at speeds above 30.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"