https://www.nps.gov/subjects/biking/ebike-regulations.htm
A couple selected items. First, in the unintended humor category:
(It's my impression that to the extent a "750 watt motor" is a thing, it's the very same thing as a 749 watt motor.)
The interesting wrinkle on the 3 class system:
(I've seen PAS zealots insist that it's required by NPS, but this clearly says it isn't. I find this gratifying, though not a big NPS user myself, just because I have the impression that the industry doesn't mind PAS-only laws a bit but they work against garage builders. It's nice to see them apparently speaking from actual experience riding a powered bicycle.)
On conflicting state regulations:
A couple selected items. First, in the unintended humor category:
The definition in the Memorandum refers to the definition of “electric bicycle” in the Consumer Product Safety Act (15 U.S.C. 2085), which limits the power of the motor to less than 750 watts. Many manufacturers sell e-bikes with motors having exactly 750 watts. In order to avoid the unintended consequence of excluding many devices from the regulatory definition of an e-bike due to a one-watt difference in power, the definition of e-bikes in this rule includes devices of not more than 750 watts.
(It's my impression that to the extent a "750 watt motor" is a thing, it's the very same thing as a 749 watt motor.)
The interesting wrinkle on the 3 class system:
Except on park roads and other locations where the use of motor vehicles by the public is allowed, the rule prohibits an operator from exclusively using the electric motor to move an e-bike without pedaling for an extended period of time. This restriction is consistent with the Policy Memorandum and intended to allow the public to use e-bikes for transportation and recreation in a similar manner to traditional bicycles. It only affects the use of Class 2 e-bikes, which have a motor that may be used exclusively to propel the e-bike.
[... and later, in the discussion ...]
The NPS has also modified the regulatory text to make clear that using the throttle on a Class 2 e-bike without pedaling is only prohibited if it is done for an extended period of time. This will help law enforcement officials focus only on the more egregious cases of users using the throttle to move Class 2 e-bikes without pedaling.
[...]
The NPS acknowledges that there may be situations where the use of the throttle-only power may be appropriate and useful in limited duration. This could be the case in particular for park visitors who use e-bikes as to access and enjoy park areas in a manner that would not be possible with traditional bicycles. In limited duration, the throttle could be used without pedaling to get started, for a quick burst of power to climb a hill, or to move safely through an intersection. In order to more precisely tailor this restriction on the use of Class 2 e-bikes, the NPS has revised the final rule to only prohibit the use of throttle-only power for an extended period of time. This change will allow riders of Class 2 e-bikes to benefit from throttle-only power for limited durations while ensuring that e-bike use, where allowed, will continue to be used in a manner that is consistent with traditional, non-motorized bicycles. Due to this change in the final rule, the NPS declines to adopt the proposal to require riders of Class 2 e-bikes to disable the throttle-only function.
(I've seen PAS zealots insist that it's required by NPS, but this clearly says it isn't. I find this gratifying, though not a big NPS user myself, just because I have the impression that the industry doesn't mind PAS-only laws a bit but they work against garage builders. It's nice to see them apparently speaking from actual experience riding a powered bicycle.)
With respect to differentiating among traditional bicycles and e-bikes, and among classes of e-bikes, the NPS notes that 28 states require e-bikes to have a label that displays the class, top assisted speed, and power outlet of the electric motor. Some e-bikes can be differentiated from traditional bicycles by simple observation. In other cases, the NPS expects that its law enforcement officers will use their specialized skill, training, and judgment to enforce this requirement even if the e-bike is not labeled through observation of riding behaviors, questioning, or other means of investigation. Identifying violations of NPS regulations that occur at speed is not a novel challenge for NPS law enforcement officers. These individuals are tasked on a daily basis with enforcing speed limits and equipment and operational requirements for the use of motor vehicles and vessels used within remote park areas. See, for example, 36 CFR parts 3 and 4.
On conflicting state regulations:
Visitor use of park areas should not be determined by the state. That is why where state law is adopted elsewhere in NPS regulations, it applies only to the extent there is no conflict with NPS regulations. The NPS declines to adopt a regulatory framework where it would defer entirely to the state on matters of visitor use, even if that deference would only occur if visitor use is more restricted by the state. This would be an abdication of the NPS’s legal responsibility to manage visitor use and enjoyment of the National Park System.