Caden Graff, front of house manager at Hills, says e-bikes come in classes. Class 1 is pedal assist up to 20 miles an hour. Class 2 is pedal assist up to 28 with a throttle up to 20. Class 3 is pedal assist only, up to 28. An unofficial Class 4, the e-moto, has only a throttle, no pedals and motorcycle speeds.

Most states and localities bar riders under 16 from Class 3 bikes. Confusion over the types means many police departments don't actively enforce the rules.

Prices run from $300 for a basic model to $15,000 for a top racing bike, and bikes at Hills run about $2,000 to $4,000. Graff warns that cheaper models come with a host of issues. The payoff is faster commutes and less sweat. The tradeoff is new safety concerns on roads and trails, and young people who want a little more zip are the ones leaning in hardest.

Asked how fast an e-moto can go, Graff says it's sky's the limit.