Mid drive watts vs human power

[bobbyrobson]

Hi all,

I was curious to know if anyone has information on the amount of watts that reach the crank from a mid drive motor, such as the BBSHD?

For instance, if I am using assist level 2 (which I have set to 200 watts), how does that compare to the power generated by a human rider?

 

[Nealh]

200 watts human power is in the terrain of semi pro or pro cyclists , your average cyclist will be 50 -100 watts with the fittest managing maybe 150 watts. The average cyclist power is only in short bursts or for a duration of approx. 30 - 60 mins.

On a final sprint to the line a tour rider can dig out a massive 1400 watts.

 

[bobbyrobson]

200 watts human power is in the terrain of semi pro or pro cyclists , your average cyclist will be 50 -100 watts with the fittest managing maybe 150 watts. The average cyclist power is only in short bursts or for a duration of approx. 30 - 60 mins.

On a final sprint to the line a tour rider can dig out a massive 1400 watts.

Sorry I think you misunderstood my question, sorry if I wasn't clear.
If I had power meter pedals or something on my bike to measure human wattage and I was outputting 200 watts, would this equal in the same power to the crank as 200w from the motor? (read from the display)
Or are there loses before it reaches there, resulting in say 160w equivalent power?

Or is it something that can't possibly be calculated unless you had a power meter installed, cycled at a certain speed that required 200w of power to maintain and then see what wattage it takes to do similar with just motor/throttle

 

[flecc]

If I had power meter pedals or something on my bike to measure human wattage and I was outputting 200 watts, would this equal in the same power to the crank as 200w from the motor? (read from the display)
Or are there loses before it reaches there, resulting in say 160w equivalent power?

The standard that Panasonic set many years ago was that on the normal power setting, the actual power into the transmission equalled the rider input, no losses.

Theie higher power setting was specified as a ratio depending on model, such as 1.5 times or 2 times the rider input, Eco setting typically half rider input.

But others like Bosch and Bafang have complicated matters since with multiple power levels. However I'm guessing they would, like Panasonic, use actual power transmitted with no losses. One exception could be some Bosch drives when they introduced the small chainwheel, since the rider the pedalled though an epicylic gear increase, meaning rider efficiency loss.
.

 

[matthewslack]

The motor will be in the region of 75 to 85% efficient by the time its output gets through its gearing to the crank, if your cadence lets it operate in it's best speed range, so for 200W electrical input I.e. from the battery, you will see 150 to 170W at the pedals.

Unless there is a torque sensor, which there is not with a BBSxx, any power measurements done by the display or controller will be electrical as there is no means to measure mechanical power in the system. So 200W reported is the electrical input and mechanical output to the crank will be lower as stated above.

 

[bobbyrobson]

The motor will be in the region of 75 to 85% efficient by the time its output gets through its gearing to the crank, if your cadence lets it operate in it's best speed range, so for 200W electrical input I.e. from the battery, you will see 150 to 170W at the pedals.

Unless there is a torque sensor, which there is not with a BBSxx, any power measurements done by the display or controller will be electrical as there is no means to measure mechanical power in the system. So 200W reported is the electrical input and mechanical output to the crank will be lower as stated above.

Thank you, exactly the info I'm looking for