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Old 02-13-07, 08:54 AM
  #16  
dalmore
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Join Date: Oct 2005
Location: Big Ring. Little Cog.
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Bikes: 2005 Dahon Speed TR, 2006 Dahon Mu SL, 2000 GT XiZang, 1999ish Rock Lobster, 2007 Dean Animas CTI

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Originally Posted by Speedo
Sort of, but not quite. Initially some of the engine's (that's you) power will have to do toward spinning the wheel up, but at speed you only have to add power to overcome friction, rolling resistance and aero drag.

...

Before you spend $400 on some fancy wheels, spend $30 on aero bars.

Speedo
While I don't find any fault with the logic you present, it doesn't explain the physical observations I have made. Try this physical experiment for yourself. Get up to speed on your bike using any means you desire. Without changing your front chainring, shift to your largest rear cog and gauge how much resistance you find on the pedal. Then while still at speed and again without changing your front chainring, shift to your smallest rear cog and gauge how much resistance you find on the pedal. There was more resistance when you were on the smaller cog yes? Friction, aero drag and rolling resistance are practically unchanged. I argue this supports my theory of the wheel as a lever. (If you are going to argue that it's the effects of gearing - look at how gearing works and see if that brings right back to the lever.) The larger cog is applying the force is a position that is more advantageous effectively shortening the lever. So if the lever theory holds to this degree, why does it suddenly not apply when trying to calculate the effects of varying the load at the end of the lever - ie more mass at the rim and tire?

As far as upgrades ... I for one can not magically reach 20 mph where the rotational mass of the tire become a flywheel and aerodynamic drag is my biggest enemy... I have to reach that 20 mph point first by exerting energy. And with the rolling terrain around here, I spend more time accelerating up hills than I do gliding down them in a tuck position. So for me, $400 on lighter wheels to get better acceleration might be a more cost effective upgrade than $30 on aero bars.
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Last edited by dalmore; 02-13-07 at 09:06 AM.
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