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It is quite easy to calculate the power PHill needed for climbing a steep hill. If there
would be no air or rolling resistance, all we need to know would be the mass m of the
rider plus bicycle, the acceleration due to gravity g (9.81 m/s²), the height
difference h of the climb, and the time t.
The work WHill (in Joule) to climb the hill is
WHill= m×
g×h
Then the power is simply the work divided by the time:
PHill= m×
g×h / t
Since we are still fighting the air resistance and rolling resistance (but at
low speeds...), we have to add this contribution PAir and
PRoll.
It depends on the effective frontal area cwA and the rolling coefficient
cr.
Look at my motion of a cyclist page for details.
But this contribution is small compared to the power needed for the climb, so
we can use a rough guess for the values for cwA (0.4) and cr
(0.005). Therefore we also need the length
of the climb to calculate the speed.
Now let's calculate the power! (Efficiency of the chain = 98%) (Click on button "Power")
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