samsbike wrote:I have read the whole thread and still am at a loss at why cadence should be measured at all and how it helps develop performance. Can someone please enlighten me.
Delivering a given power output has different physiological demands at different cadences. It's clear that extreme cadences are impractical - imagine trying to push out 300W at 5rpm, or 300rpm. In between these extremities lie a range of usable cadences which will stress your body in different ways.
Lower cadences will tend to put additional pressure on your joints as the pedals are harder to turn. Also, the natural tendency of the bike is to slow down between the power phases of the pedal stroke, and this slowing and subsequent re-acceleration is inefficient. The lower the cadence, the longer is this period of potential slowing, so the more effort is required to resist it, using less efficient muscles.
In contrast, higher cadences have the potential for a smoother, lighter action (less pressure, shorter periods of low power output), but are likely to be more tiring in a cardio-vascular sense. When cadences get very high, joints again become an issue as the pedalling action becomes less controlled.
It follows that it's worth experimenting with how your own body copes with different cadences, to find out which gear will allow you to cycle most efficiently in a given situation (where "efficiently" might mean "to maximize power" or "to minimize tiredness"). Both the experimentation, and the use of that data, require measurement of cadence (or calculation of same from speed and gear ratio).
[My perspective on this is as a some time road cyclist who has been riding mainly fixed gear for the last year. I really enjoy being forced to pedal at widely differing speeds, and it has noticeably improved my speed on the road bike. So, if you don't want to go through the hassle of measuring your performance at different cadences, just get a fixie and improve all of 'em! ]