What is "wattage?"

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What wattage means

Electric bike conversion kits are often listed by wattage (the same kind of watts used to describe lightbulb power). Some electric bikes and kits may be listed as 150w (watts), and others as much as 600w or more. But the important thing to realize is that there is no ratings agency that makes sure these claims are valid. Manufacturers can say anything they want, so the ratings don't really mean much. We've seen many products on the market that claim to be high-watt motors (600 watts or more), that aren't. If you use them for very long at the rated watts, they will burn out. Other motors are rated too low, because in some areas of the world (like Europe) there is a limit on maximum power. So motors are under-rated to appear to comply. The BMC V1 motor kit is rated at 400 watts, but that doesn't tell the whole story.

For a reputable company like BMC (who has been making brushless motors of all kinds for years), they want to make sure their electric motor kits will last for the long haul. So they intentionally under-rate their power. This is a common trick known to engineers - figure out what the maximum load of your bridge/motor/building/stairway is, then rate it at a fraction of that amount so that it is always used well below maximum. It will last a lot longer that way. So for the BMC V1 kit, a rating of 400 watts really means that you could operate the kit constantly at 400 watts, for many years, and get reliable service out of it. And 400 watts is a lot of power. For comparison, a professional bike racer might produce 400 watts in short bursts, but they can't keep doing that for more than a few minutes. So, having a 400 watt motor on your bike is like having a tireless professional bike racer helping you pedal your bike. But 400 watts isn't the whole story. These motors can actually produce much more than 400 watts, say if you are going up a steep hill, or need to accelerate across an intersection. For the BMC V1 kit, the peak poweris around 800-1000 watts. That means you will have almost as much power as two professional athletes, at your fingertips.