The recommendation depends a lot on what you plan to use the bike for and how you plan to ride. That said, I would recommend at least a 750 (if not 1,000) watt motor, and, if you want reasonable range, 48 or 52v cells with a minimum rating of 19ah. For shorter rides, you can use a smaller battery. Multiply battery voltage by amp hour rating to get battery watt hours. Divide the watt hours by the motors power rating to get a general idea of how many hours of heavy use you might get. I’d also recommend a mid drive as opposed to a hub drive, or to find a hub drive wheel rated to take your and the bicycle's combined weight.

Oklahoma defines an Electric-Assisted Bicycle in 47 O.S. 1-104 [122] as "Two or three wheels; and Fully operative pedals for human propulsion and equipped with an electric motor with a power output not to exceed one thousand (1,000) watts, incapable of propelling the device at a speed of more than thirty (30) miles per hour on level ground, and incapable of further increasing the speed of the device when human power alone is used to propel the device at a speed of thirty (30) miles per hour or more. An electric-assisted bicycle shall meet the requirements of the Federal Motor Vehicle Safety Standards as set forth in federal regulations and shall operate in such a manner that the electric motor disengages or ceases to function when the brakes are applied."
The Dew-E packs functionality and fun into a rather traditional and conservative package. Front and rear fenders, integrated Busch & Müller front and rear lights, and a built-in Abus wheel lock make this a very practical commuter bike. An 11-34, 9-speed cassette and 1.75-inch tires provide versatility: You’ll ride smooth over rough city streets and zip down gravel bike paths with confidence. Front and rear rack mounts also give you the chance to outfit this bike for carrying more cargo or supplies for a longer day on the bike.
I have been able to find ebikes of all speeds out in the wild and after years of riding and a reflective posture for the law, I see that lawmakers were thinking less about me and my practical wants as the user, and more about the mass motor vehicle driving public, their perceptions and expectations of ‘typical bicycle speeds’ on the roads and paths. So the laws were made to bicycle NORMS, not the potential performance limits for users.
This dexterous electric dirt bike is recommended for anyone over the age of 14. It’s fitted with double suspension and big tyres to help you tackle tough terrain. You also get a good selection of gears, that gives you optimal control. The Razor can go as fast as 20 mph, and comes with an excellent braking system. The aesthetics are on point, and the racer look is sure to impress. Don’t forget your helmet!
At the top end, the 20mph speed limit isn't an absolute, like the speed of light. It's just the most you'll get from the motor. I was able to get it up to 28mph on a flat road (there are no other roads where I live) in Turbo mode and 8th gear, but it took hard work to get there and maintain the speed. The easiest comparison is my mountain bike, where I've hit 23mph on that same stretch of road—and that took a heck of a lot of effort. Exactly how much effort does it take to ride? I have a 15-mile route that I ride on both my mountain bike and cyclecross bike. According to my Apple Watch, I generally burn around 1,400 or so calories on a brisk ride. I'll probably average around 13mph or so on my Marlin and between 16 and 17.5mph on my XO2. I averaged 14.9mph and burned a hair over 1,000 calories with the Bulls Cross E8.
We've also released our first native 72V battery pack in a conventional downtube battery casing, assembled using the high power Samsung 27100 40T cells so that even with the small 8Ah capacity it is able to deliver 40-50A continuous currents. This is an ideal battery for fast and sporty offroad ebike builds, allowing powerful performance without the weight or complexity of most 72V setups (either two 36V packs in series or a large triangle frame battery).
My one complaint is the bike’s weight. This sucker is heavy! The aluminum frame looks light, but the the hub motor (4 pounds) and battery (5 pounds) add up. The bike’s total weight is 39 pounds, which is about average for e-bikes but not something you’d want to lug around all day. “This is not a solution for everybody,” Miller admits. “If you live in a fifth floor walkup this is probably not going to work.”

This Class 3 (28 mph), utilitarian, road e-bike is smooth and torquey thanks to its Bosch Performance Speed motor. With a drop bar and traditional road-bike position and handling, the CrossRip+ is more suited to longer rides on mixed terrain than navigating congested city streets. It comes with a rear rack—for mounting bags, not for attaching cargo directly—full fenders, a kickstand, and integrated front and rear lights (which are powered by a Bosch 500Wh battery). It features a SRAM Force 1x11 drivetrain, hydraulic disc brakes, and wide 700x38mm tires.
I purchased version 2.0 of this device and the manufacturer has been listening to comments from users and making running changes such as the three speeds and the rear suspension. I am an XL size user (6'2", 230lbs) and recently returned from a 26 day cruise around Europe. I rode this little scooter on cobblestones, miles and miles through the Vatican, inside ancient cities and all over the streets of San Juan upon our return stateside. There was only one time it was less than ideal and that was going uphill, on slick tile that was wet from a drizzle. It still make it, just had to lean way forward to get weight on the front wheel.