Power to the Pedals

Whether we know it or not, we cyclists are all about power.

Power is the rate at which energy is used.  More simply it is the ability to do work.  Horse Power was originally a term used to compare the work-abilty of draft horses to steam engines.  One horse power is 550 foot pounds per second.  That’s the abiity to lift a 550 pound load by one foot, in one second.  Since very few of us are capable of hitting that mark, even briefly, it makes a bit more sense to use the SI power unit of Watts.  And for those of you who are of inquiring mind, the conversion is roughly 746 Watts (W) to 1 Horsepower (Hp).

When we move by bicycle there are three physical resistances to our progress.  They are Friction, Air Drag, and Gravity.  Of these Friction is negligible, but both Air Drag and gravity are tough.  The faster we go, or the higher we climb the more resistance we meet.  Power is all we have to overcome that resistance.

Where does it come from, this power?  A cyclist’s answer would be,  “From my legs!”  But it is far more complicated than that.  Power is the rate at which energy is used.  So where does the energy come from, and how is it converted to power?  That gets a bit more complicated, but we can go with the cyclists answer.  It comes from the legs.

Want to know how we bike riders stack up?  Some of the mightiest and strongest of us can generate about 1.5 horse power, for a very short time.  Our elite Pro super-sprinters can deliver close to 1 Hp for as long as 15 or 20 seconds.  Then they are done.

Look around you at the next group ride.  You know who the “power riders” are.  Most likely the strongest of them can not sustain as much power as a leaf blower makes.  A good strong rider can deliver something like 250 to 300 Watts for several hours.  That’s about enough power to light up a moderate sized room, or to blow the leaves out of one medium sized driveway.  Hmm.  No wonder we seek the most efficient and lightes bicycles we can find.

How do we develop power?  What makes it happen?  How can we get more of it?  How can we keep it going?

Those are the questions, and this week we’ll devote time and space to Power.