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  • Bicycle pedal torque applied by foot

    Discussion in 'The main mechanical design forum' started by ahad_yekta2004, Mar 16, 2010.

    1. ahad_yekta2004

      ahad_yekta2004 New Member

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      how much is the torque that a usual person enter over the bicycle pedal ? ( the range )
      i want to know . is it enough to ride a bicycle through drastic uphill bye foot power? or use some booster to drive better . i want to design a hydraulic transmition for bicycle . do i have to use pressure booster to increase the force on rear wheel or the 1:1 transmited turk is enough ?
       
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    3. deltabarn

      deltabarn New Member

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      Action and reaction my friend. If a person does not turn the pedal then he will stand on it and so the maximum torque will = (body mass of the rider x g) x the length of the pedal lever. Remember to consider the gearing of the bike though.
       
    4. ahad_yekta2004

      ahad_yekta2004 New Member

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      tanx for your reply .
      but i didnt mean the max of force . what is the average force over pedal when rider is sitting on bicycle seat . i should consider the usual condition .
       
    5. ConnectUTS

      ConnectUTS Active Member

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      According to http://www.green-trust.org/2000/humanpower.htm "The average, fit, adult rider can produce only 75 watts or 1/10hp when cycling at a continuous 12mph (19.3kph)." This usually happens with a pedaling speed of 60-80 rpm though many rider pedal faster. When I cycle, I usually spin at between 100-120 rpm, but I have been riding for years and have found that the higher speed works better for me.

      To determine what type of mechanical advantage you will need to build into the system need to know the speed you want to travel and the diameter of the wheel [http://www.sheldonbrown.com/rim-sizing.html]. For this discussion we will use approximately 1/2 the speed listed above or 10kph and a wheel diameter of 700C which translates to 1.954 meters in circumference.

      To travel at 10kph the bicycle tire will be spinning at at approximately 86 RPM. As a result if 75 watts is enough then a 1 to 1 gear ratio should work.

      I will let you do the rest of the calculations.
       
    6. jawnn

      jawnn Well-Known Member

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      I remember an old bike magazine article that seemed to prove that most people did not press on the pedals as much as they thought they did. I don’t know how they measured the pressure, but I can see how it would be close to un-measurable, turning so fast.

      Is it really possible to improve the bicycle? My hill climbing is done with very low gears. I also think that this entire obsession with speed is a disease. I would really like to see some slow technology.
       
      Last edited: Jan 30, 2012
    7. jawnn

      jawnn Well-Known Member

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      Have you considered compressed air? I need some sort of light weight power system for a velomobile. I Worked up an electrical system but it was going to need one hundred lbs of batterers.
       
    8. Dana

      Dana Well-Known Member

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      A hydraulic transmission is a very inefficient way to transmit power; you'd be making the rider work a lot harder than he would have to with conventional gearing. Hydraulic (usually called hydrostatic drives) have their place when fine control at low speed is required, but a bicycle drive isn't one of those places.
       
    9. jawnn

      jawnn Well-Known Member

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