Relationship between degrees, percent slope, and ratio
- Thread starter Doctorbass
- Start date
Dalecv
1 W
How can ya make any sense out of it when the degrees aren't specified C or F. :?
TylerDurden
100 GW
Dalecv said:
Don't matter... if you work for NASA. :lol:
Ben
100 W
Dalecv said:
OK, it's really hard to tell if you're being serious or not. My guess is that they're in Celsius
Dalecv
1 W
Okay, so it is metric. Now that we have that cleared up we won't crash our EVs on the back side of Mars. But we all know that you can't give more than 100% except for coaches. This thing is all screwed up. :wink:
Ben
100 W
I'd just like to point out that degrees is in fact in terms of degrees, as in the angle (degrees & radians). Yes, I know I said degrees Celsius, I was pulling your leg.
xyster
10 MW
Ben said:Dalecv said:
OK, it's really hard to tell if you're being serious or not. My guess is that they're in Celsius
He's from Eugene, so I figured he was probably serious -- you know, a brain-fried old hippie -- but I didn't want to say anything. :wink:
Dalecv
1 W
Sorry all, I was doing maintenance on my computer and all of the downloads were making my distorted view of reality worser and worser.
I think the chart does an excellent job in showing the relationship of how slopes are expressed.
Now then, using the next article posted I figure I can use my CA to determine slope percentage while riding.
If my bike consumes 500 watts while traveling at 20 mph on level ground, when I come to a hill and ride up it at the same speed I should be able to determine the slope by the increase in power consumption. Such as, if my power consumption increases to 550 watts then the slope of the hill should be about 10%. Or is my non mathematical brain deluding me again?
I think the chart does an excellent job in showing the relationship of how slopes are expressed.
Now then, using the next article posted I figure I can use my CA to determine slope percentage while riding.
If my bike consumes 500 watts while traveling at 20 mph on level ground, when I come to a hill and ride up it at the same speed I should be able to determine the slope by the increase in power consumption. Such as, if my power consumption increases to 550 watts then the slope of the hill should be about 10%. Or is my non mathematical brain deluding me again?
xyster
10 MW
Dalecv said:
The bicycle speed and power calculator takes into account most of the major factors necessary to make that calculation accurately. According the calculator, maintaining ~20mph up a 10% grade requires about four times as much power compared to level pavement (~1600W versus ~400W):
http://www.kreuzotter.de/english/espeed.htm
The calculator uses power at the wheel, and not the input power. So to get a more accurate answer, correct for your system's efficiency by dividing your power number by system efficiency of 70-80%. For example, 400W at the wheel means 500W from the battery.
Dalecv
1 W
That number looked too small and of course it was. I was trying to interpret paragraph 3 of 9.3 Road Gradient Units,
The kreuzotter page can calculate theoretical power quantities but is to generalized for what I want.
With my CA I know what my power consumption is on the flat and level with the current temperature, air pressure and wind conditions. Now, how steep is the hill I am going over?
I couldn't find this information put this way but I calculate that 1 watt equals 1 pound being raised 44.25 feet in one minute. At 20 mph you raise 176 feet in one minute so you have a theoretical power consumption of 3.977 watts per pound. Calculate an inefficiency power loss of 20% so a more realistic power consumption of 4.77 watts per pound. Now all one has to do is multiply the total weigh of rider and bike by 4.77 and you can then determine how many addition watts it takes to climb a 10 % grade at 20 mph. While going up a hill check the CA for power use and subtract the amount of watts used on flat ground then you can estimate grade.
I am sure you all will help me refine this.
and how to calculate power consumption.
The kreuzotter page can calculate theoretical power quantities but is to generalized for what I want.
With my CA I know what my power consumption is on the flat and level with the current temperature, air pressure and wind conditions. Now, how steep is the hill I am going over?
I couldn't find this information put this way but I calculate that 1 watt equals 1 pound being raised 44.25 feet in one minute. At 20 mph you raise 176 feet in one minute so you have a theoretical power consumption of 3.977 watts per pound. Calculate an inefficiency power loss of 20% so a more realistic power consumption of 4.77 watts per pound. Now all one has to do is multiply the total weigh of rider and bike by 4.77 and you can then determine how many addition watts it takes to climb a 10 % grade at 20 mph. While going up a hill check the CA for power use and subtract the amount of watts used on flat ground then you can estimate grade.
I am sure you all will help me refine this.
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