What I don't understand is, if there is a posted speed limit, what difference does it make between Class 1 & 3? After all, a Class 1 bike can exceed 15mph just as my car can exceed every posted speed limit. But due to many valid and not-so-valid complaints, our local trails are now getting more serious about specifying their e-bike rules, and most are stated as Class 1 or Class 1 & 2 only.
Since these are state-recognized classifications (Michigan), it is pointed out that altering the class sticker is illegal. So that's where I draw the line. If I'm "caught" riding a Class 3 bike I can probably claim ignorance or get off with a warning, but if I've altered the class sticker, it shows willful intent to violate the rules and could theoretically result in a hefty fine and/or confiscation.
That said, I've never seen any indication of enforcement so, frankly, I'm not going to worry about it (until "caught!").