Bike Motor Wattage

[TML]

So in looking for the best e bike for my budget; I've seen a lot of crazy things around e bike wattage.

One of the bikes recommended to me on this site lists a 500w rear hub motor, but upon further inspection the battery is 48v and the controller is 26a. At full throttle the bike is laying down nearly 1250 watts!

How are manufacturers getting their numbers for motor wattage? Are these just made up at random for marketing or is there a magic formula that shows what they are good for under continuous load? Is there any type of chart that shows the real numbers you can throw through at a motor?

So many questions.

Having the real performance numbers would be greatly helpful as there are so many 350-500w rated motors on bikes now.

 

[Mr. Coffee]

You are absolutely correct that manufacturers are, um, creatively explaining their wattage figures.

Keep in mind that a lot of times regulatory limits require that motors be rated at or below a certain wattage for the bicycle to be street legal in Europe or the States. Also, you are correct that there is a big difference between potential peak output (which you can roughly estimate by multiplying battery voltage by controller output current) and continuous output. And there are a great many ways and no clear standard way to measure continuous output.

What makes this even worse is that some manufacturers willfully and often ridiculously overstate the power output of their motors.

 

[Bruce Arnold]

Yep, you figured that one out pretty quickly, @TML . Here's another one you'll see: Maximum distance = X miles. They don't tell you how they arrived at that number. There are a couple of more reputable companies who do say how they arrived at their mileage estimate but there's a lot of -- umm -- embroidery around things like watt ratings and mileage per charge.

Speed ratings are generally more reliable. If a Class 3 speed pedelec says it can go up to 28 mph, it probably can, because that's what speed pedelecs do. Battery ratings -- X volts, Y amp-hours -- are pretty reliable.

Ignore the hyperbole. Watch Court's videos here on EBR, read his reviews, and then read the sub-forum for any brand that you are interested in. You will get real-world experience.

 

[mrgold35]

It really depends on your budget, riding environment, and how you plan on using the ebike can be a factor also. I went with the 2016 Radrover 4" fat tire 750w/48v geared rear hub because of:
- price of $1500
- TQ of 80 nm
- well within my range of under 40 miles max
- 18-22 mph work commute speeds were perfect for me
- throttle comes in handy for work commuting and trail riding
- utility with adding a rear rack for more cargo capacity
- ability of having one ebike being a "jack of all trades and master of none"
- very easy to modify with upgrades like brakes, accessories, pedals, battery, lights, etc...

My original game plan was I would purchase this inexpensive ebike and upgrade to mid-drive once I get more experience on the ebike learning curve a few years later. After almost 2 years and +4500 miles, I'm still extremely happy with my starter ebike and have zero plans to upgrade.

Depending on your budget, you can sometimes purchase 2 and sometimes 3 rear hub ebikes for the price of 1 mid-drive. I have two Radrovers and one RadCity Step-Thru for $4500 with a lot of family outings to go along with them.