The highways of sparsely populated Montana once offered an interesting alternative to speed limits. Rather than dictate a posted speed limit for motorists, traffic laws simply advised drivers to move at a speed they found “reasonable and prudent.” With no one able to agree what this meant—and some drivers being anything but reasonable—the experiment failed, and it was back to hard limits.\nSometimes it can seem as if cyclists across America only need to be reasonable and prudent in their adherence to speed limits. After all, a bike can’t outrun a Corvette. However, those of us who like to improve our bikes by installing e-bike technology should know that there are limits to the speeds we can achieve. You’ve probably wondered just how fast you can drive an e-bike on the road. Let’s take a look.\nBy the Numbers\nManufacturers and local laws divide e-bikes into three classes:\n\nClass One: Pedal-assist-only e-bikes.\nClass Two: Pedal-assist with throttle control.\nClass Three: High-speed pedal-assist with optional throttle.\n\nThe motors in Classes One and Two stop supplying power when an internal speedometer reaches 20 mph, at which point any further velocity must come from pedaling. Class Three e-bikes attain speeds of 28 mph before the motor shuts off—a distinction that often brings about stricter regulations. E-bike motor kits from Ebike Essentials can elevate your cycling speed past 25 mph with hard work, motorized pedal assistance, and perhaps a little downhill movement. Whether you can do so on the road, however, is more complicated.\nFollow Posted Speed Limits (Even the Ones for Cars)\n“Share the road” has been a rallying cry of cyclists for years; it urges car and truck drivers to leave room on the roadways for bikes. The other side of that deal is that cyclists who share the road must adhere to the rules of the road just as motorists do. That means that posted speed limits apply to e-bikes as well as cars. In school zones or high-density areas where speed limits fall below 20 mph, it’s possible to exceed that limit on an e-bike when the conditions are just right. It’s also possible that a police officer could choose to pull you over and cite you for speeding. Don’t get carried away in areas that post low speed limits—the signs are there for a reason, and you could endanger yourself and others by breaching them.\nE-Biking in the Big Cities\nHow fast can you drive an e-bike on the road in America’s largest cities? In New York, where acceptance of e-bikes has been a late arrival, staying under 20 mph on the city’s congested streets and avenues is a must. Out on the West Coast, Los Angeles observes the California-wide rules for e-bike speeds; pedal assistance isn’t allowed to exceed 20 or 28 mph. Chicago’s popular Divvy bike-share service, however, has recently throttled its fleet in the dense Windy City by limiting pedal assistance at 15 mph—all the more reason to have an e-bike of your own.