Richard N
100 W
Alan B said:The question you probably want to ask first is how much thrust does your planned bike require at your planned speed. Use a bicycle power simulation to determine that first (you may want to do it for level, and your worst case hill, at appropriate speeds for each). Then, for each motor, adjust the throttle to produce that amount of thrust at that speed. Then you can actually compare the results at that speed and see the efficiency, as well as how much throttle is required.
On these wide open throttle graphs you posted, looking at the thrust at 20mph is telling you the maximum thrust it can produce at that speed, and the efficiency and power at that maximum thrust. So you can't tell what the efficiency at the actual thrust you will be using is.
I sort of tried to do that back on page one, I do have some hills around here but none are really long or overly steep. I've estimated the best I can without topo maps or GPS readings that my steepest hill will be 10% for no more than a few typical city blocks, 200 yards at the longest, best guess.
Keeping in mind that I'm building a cargo bike I loaded it right up with weight and I came up with a power requirement of 1638 watts for that 10% grade and a speed of 15kmh or just under 10mph, that same load on the flat would need 390 watts. The cargo unloaded totals were, hill 806 watts and flat 325 if I recall correctly, I honestly can't remember what I put the bikes+cargo weight at but it would have been around 450lbs.
I'll go back over to the motor simulator and have another crack at it.