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## Main Question or Discussion Point

I'm trying to deduce the forces acting on a cyclist going up a hill and I need help. There's 2 questions:

I've looked at online calculator already in existence:

What puzzles me about these calculators is when I caculate the parallel force I get numbers that are different to these calculator. but are the same as

Following on from this, what I am trying to do is calculate what the force are acting on the rider by doing a calibration run down the hill, the other forces (air resistance (wind, pressure), friction) besides gravity being the difference between the force on the calibration run and a hypothetical run just with the force of gravity.

So that when the rider goes up hill in X amount of time we can calculate the how much work against gravity by itself and all the other forces rolled together (deduced from the calibration run).

Am I missing something fundamental?

**Q.1**I've looked at online calculator already in existence:

*http://www.analyticcycling.com/ForcesPower_Page.html*

http://www.gribble.org/cycling/power_v_speed.htmlhttp://www.gribble.org/cycling/power_v_speed.html

What puzzles me about these calculators is when I caculate the parallel force I get numbers that are different to these calculator. but are the same as

*http://thecraftycanvas.com/library/online-learning-tools/physics-homework-helpers/incline-force-calculator-problem-solver/*

**e.g.**for a 5º slope and a 78 kg rider+equipment:*-9.81 * sin(rad5) * 78 = 66.6 N*"thecraftycanvas.com" get the same result, yet Gribble and Analytic cycling get 38.2 N**Q.2**Following on from this, what I am trying to do is calculate what the force are acting on the rider by doing a calibration run down the hill, the other forces (air resistance (wind, pressure), friction) besides gravity being the difference between the force on the calibration run and a hypothetical run just with the force of gravity.

So that when the rider goes up hill in X amount of time we can calculate the how much work against gravity by itself and all the other forces rolled together (deduced from the calibration run).

Am I missing something fundamental?