Legal implicatons of riding dual drive gas electric motorized bike

[Frankenstein]

Newer Ryobi lithium batteries have a rated max discharge rate of 72 Wh (older ones were 48 Wh). According to my math (not my strong suit), 500 watt (hub motor @ 36 volts) / 72 watts @ 18 volts = 7 then x 2 to adj voltage = about 14 batteries minimum for full power. 14 batteries x 1.7 lbs each = about 24 lbs. Add in about 10 lbs for motor related =34 lbs. Not real practical due to the low amperage support from each battery.

This product seems to defy all the rules:

https://comingsoon-tech.com/urbanx-smart-electric-bike-wheel/

Apparently just now hitting the U.S. shores for sale after a kickstarter promotion, this hub motor uses a 36 volt battery that my guess weighs about 4 lbs, rated to propel the bike up to 20 mph, for up to 30 miles. Snap in, on the fly replacement batteries, low center of gravity and good weight distribution on the bike. The entire drive including batteries weighs 18 lbs. This drive is also considered to be strong for off road use. Make note of the flat rate $80 domestic shipping charge bringing the 350 watt version to about $520 with fork support hardware.

I seem to remember mention of a electric braking feature, and that would be a cool; but this may may not be on this model (V2). This product could be a candidate as a performance mod to a single speed gas powered bike. Someone buy one, report back and tell me if this thing is for real.

20mph for the larger and more expensive of the 2 versions, with the 350w motor.

The battery is a mear 3.5 amps worth of 36v...126wh

That motor on full tilt will eat that up in ideally a little over 20 minutes, but since that's not how load on a battery works in real life expect about less than 20 minutes, and that's of course without stopping at all and starting again from a stop, that all adds up.

They even say the words 'and get a tiny boost along the way' No kidding right?

Maybe hijacking the battery pack and carrying some bigger batteries on board (or behind in a trailer) would be worthy of exploration and exploitation. The product definitely seems set in stone and the concept actually works enough and doesn't really scream bulls**t to me, but the advertisers are definitely good at using those numbers to sell the product.

Step back and realize it's not as glorious as it looks on the web page, once you get the math in the way it's as obvious as it was at first glance, big enough motor with a tiny battery. But we know how to fix that now don't we?

 

[KCvale]

But we know how to fix that now don't we?

You bet, just get a bigger battery!

That 7-speed shifter just flew.

 

[Wolfshoes]

As a footnote to the math calculations made I made in this thread (if they are right); 14 - Ryobi 4 Ah batteries weighing a total of 24 lbs would be what is needed, roughly in theory, to provide a 500 watt hub motor full power for one hour. The information provided is insufficient to know the maximum discharge rate a smaller battery set can and will provide without problems such as overheating. Electric hubs including batteries such as Urban-X are providing the motor full power with far less batteries than what would be needed for one hour of riding. Therefore, the amp draw can exceed the one hour rating of discharge.

From the sparse information provided from a supplier, it should be possible create and use a table to estimate the available motor run time at full power and bike travel distance of any motor - battery set, under the best of conditions. Information the hardware vendor could calculate for you.