Cadence

I started the cadencemeter after I had got out of town and warmed up because my cadenc is slow when I start off. It made a bit of difference, though I did work at my cadence and the Av. was 90.The highest so far. The strange thing was that my HR was much higher though I never seemed to be that much out of breath with the higher cadence.My Av. HR 122 was 78% of max. I will try to observe what happens next ride and take careful note.

Back to the internet.

One of the primary results of this study demonstrated that gross efficiency (a basic measure of the total energy required) at 275 W was similar across the three cadences. In other words, it took the same amount of energy to pedal at 275 W at 80, 100, or 120 rpm. Heart rate was higher with increasing cadence though.
On the other hand, what did become impaired at 120 rpm compared with 80 and 100 rpm were the peak wattage at the point of exhaustion, the wattage at ventilatory threshold (where your breathing becomes laboured and inefficient), and a trend towards a lower wattage at lactate threshold.

So while cadence didn’t seem to impair performance at a high but submaximal wattage, it did seem to cause earlier “fatigue” when at maximal sustained effort. The authors hypothesized that this may be due to: 1) fatigue and greater energy required simply to move the legs at the higher speed (remember, while you may be pushing against less resistance with each pedal stroke, it costs more energy to move 120 times compared to 100 times even against no resistance), and 2) the higher speed of movement caused greater recruitment of fast-twitch muscle fibres, which are less efficient aerobically and produce more lactic acid.

However, lowest oxygen cost at around 60rpm, for both experienced and inexperienced cyclists, supports the idea that ‘grinding’ reduces oxygen cost [6]. It may be that 200Watts was too little to stress the experienced riders and more competitive effort (300-350Watts) may have increased preferred cadence. It seems that we all make a complicated assessment of the sensory data coming back from our legs, lungs and head. Grinding lower cadences may be a lower oxygen cost, but the neural system gets tired sooner.
Higher cadence equals better blood flow

The legs act as a more effective blood pumping system when the cadence is higher – if you hit a faster cadence the heart output increases [7]. For the same power output (200Watts as used by Gotshal, 1996) higher cadences make for better muscle blood flow, and in-line with reduced muscle strain data, it makes for better endurance. At 200 Watts (around 20mph) if you spin 100rpm your strain works out at just two Watts per rev, whereas at 60rpm your strain is over three Watts per rev.

Any rider who has ever ridden with power and cadence data to view, using SRM, Polar, PowerTap, Ergomo, Tacx or Cateye, can feel the difference that changes in cadence produce in leg tension, if Wattage stays constant. And here’s the crux: If you use this variety of gearing, power and perceived effort, you can vary training to develop your ability – in other words: Get fitter, faster and better. Now who doesn’t want that!

Well I think there's part of the answer.My heart was working harder but my legs took much less strain. I must therefore find a balance between the two extremes.

The lowest amount of oxygen was used when pedalling at 60-70rpm, significantly less than 80-100rpm. So, muscles have better neural efficiency when spinning, but this increases oxygen cost. To what extent these can be further trained is not clear, but the fact that professionals can ride at high cadences for hours and that club-level riders tend to ride in ever lower cadences as they tire, suggests cadence is a vital parameter for training. , the lowest amount of oxygen was used when pedalling at 60-70rpm, significantly less than 80-100rpm [3]. So, muscles have better neural efficiency when spinning, but this increases oxygen cost. To what extent these can be further trained is not clear, but the fact that professionals can ride at high cadences for hours and that club-level riders tend to ride in ever lower cadences as they tire, suggests cadence is a vital parameter for training.

The most efficient cadence for a cyclist is the one that requires the least amount of energy.

Well in a way its a bit confusing.