Power calculator

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Re: Power calculator

Postby Miles » Thu Jan 16, 2014 1:08 am

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Re: Power calculator

Postby made_in_the_alps_legacy » Thu Jan 16, 2014 1:15 am

From a very good doc
The Aerodynamics of Human-Powered Land Vehicles
Albert Gross Chester Kyle Douglas Malewicki
Image

Read the complete doc HERE
Pay attention to the chart on page 6 :
Image
Last edited by made_in_the_alps_legacy on Thu Jan 16, 2014 1:59 am, edited 1 time in total. View post history.
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Re: Power calculator

Postby Miles » Thu Jan 16, 2014 1:16 am

:) Thanks!
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Re: Power calculator

Postby made_in_the_alps_legacy » Thu Jan 16, 2014 1:32 am

Glad u like it
Thank U ...for cleaning up my redondant messages :wink:
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Re: Power calculator

Postby mountain biker » Fri May 08, 2015 5:00 pm

hey appreciate that...wow sounds like you guys are into some serious calculations....but i am still stumped..the question revolves around how can i use this for a mid drive calculator...

i.e....let say you got a gng mid drive...say 20 to 1 is final ratio at crank...the motor is 24 volt...3650 rpm....controll allows 21 amps....

potetially motor could run at 175 rpm at crank maybe..more like 150 rpm is max... then it is driven through the bike gears...

lets say...1.3 to 1 first and then seven others going down from a 38 t crank...to 44 cassete to 18 t....

how could i use this for these calculators.. i would like to know the amount of power transferred to the bike wheels...

wouldn't a 1000 watts of power have different speeds and load capacities if geared differently....i just can't figure out the above charsts..but i would love to...i am thanking you guys in advance..bar none this is some pretty cool techinical stuff...the reason i am asking is i am trying to figure out what gearing i need in order to use a 24 volt motor...i know crazy but hey this is what we do here.

200 pound man 50 pound bike 250 for it all lets say...pounds...different inclines 2 and 4 and 6 and 8 and 10 and 12 percent......final speed would be interesting..i guesse as long as rpm is running around 50 to 90 percent would be cool.
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Re: Power calculator

Postby mountain biker » Fri May 08, 2015 10:38 pm

okay went to the thread and omg i was amazed...you must go to the end to get the updated version and man it is awesome.....you guys are really helpful and really smart.......thank you.
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Re: Power calculator

Postby rimrock » Sun Jun 11, 2017 4:25 pm

Miles wrote:Revision 6 as an Excel file:


I downloaded this and tried to run it. I got the following message:

Screen Shot 2017-06-11 at 2.18.45 PM.png
Screen Shot 2017-06-11 at 2.18.45 PM.png (32.52 KiB) Viewed 151 times


I'm running

Screen Shot 2017-06-11 at 2.20.34 PM.png
Screen Shot 2017-06-11 at 2.20.34 PM.png (37.04 KiB) Viewed 151 times


The spreadsheet appears to work fine.
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Re: Power calculator

Postby Miles » Mon Jun 12, 2017 3:44 am

Thanks for the feedback. Do let me know if any errors surface during use.

I saved it as an Excel file using Libre Office.
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Re: Power calculator

Postby swbluto » Mon Jun 12, 2017 12:31 pm

Okay, time to interject here.

There's a minimum amount of energy needed to climb a hill.
Then there's the minimum amount of energy to push away air molecules at a given speed.

Energy to climb hill = The sum of both of those.

So, yes, speed matters, but there's going to be a minimum amount of energy necessary to lift weight up a hill, regardless if you're going 0.1 mph. Tall hill+lots weight = the minimum is going to be A LOT of energy.
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