I question the safety of many * Bicycle wheels * Can they handle the speed and torque of a powered bike ? I'd encourage legislation making ' Speed Rated ' bicycles, Ideally suited for motor conversion, available to handle the extra horsepower . I've seen too many ' Mickey Mouse ' conversions fail, causing injury. With good parts, the bikes are as safe as their owner.
I like both your and Big Blue's post. But, my very incomplete knowledge of those referenced "good parts" notwithstanding, I think Big Blue makes the best case. Want to go 40? Buy a used scooter or m'cycle. Insured. Parts available. Much less unsafe. If you can't get an M1 license I don't want you on the road with me anyhow. Competitive in price, at least compared to scratch builders like me, who waste money on rework.
As an engineer, I DO have some idea of what I don't know about the engineering that goes into all US sold, factory built 2 wheeled 30+ m/h vehicles. I'm guessing a lot. But I do know that when you crash, you need to dissipate kinetic energy, which has a v^2 term in it. So 30 hurts LOTS more than 20. So, I think a list of what needs to be beefed up or completely redesigned for higher speeds would include brakes, frame, tires, mountings, handlebars, and the many things I'm missing. Are the current crop of manly 40-50 m/h kits safe? A relative term, but they are certainly less safe than my girly 1.6 hp, 19 m/h recumbent tandem. Guarantee. And even with the best intentions, fast bike kit QC goes out the window when you sell it to moron like me to install.....
Critical FYI. I admire every fast bike builder who's posted here. They seem quite responsible, great build knowledge, and I'm sure they stand by their work. But, unless their products are produced with all the bells and whistles of a good quality scooter/m'cycle (static and dynamic load/stress computer simulations, adequate crash testing, certified parts, etc), I would no more ride one of these fast bikes than fly my paramotor from under a canopy of stitched together bed sheets.
