I read somewhere that steady cadence is a good thing but why is that? It is analogous to running long distance where it is a good idea to set a reasonable pace and stick to it? I would think that varying your cadence would give your muscles a chance to rest some. I question whether the original claim is actually true. I would think it would be more efficient to accelerate briskly then coast down, then repeat.
This "sawtooth" cadence question is interesting because with a car or motorcycle, you actually get better gas mileage if you accelerate briskly and then just coast down. For example, you are at a red light in pole position (first). The light then turns green. You then accelerate quickly up to the speed limit (say 50 MPH) and then let the car/motorcycle coast down to maybe 20 MPH and then repeat. This is actually more efficient (you will use less gasoline) than if you accelerated slowly and maintained the 50 mph. This has already been confirmed by many people that have tested it. It is also easy to confirm yourself, especially if you have a real time mileage display. It will be at maybe 10 MPG for a brief time while you accelerate then vary between 99 and and some lower number as you coast down.
Ok now to bikes. It seems to make sense that for a bike a similar thing should happen. Imagine a person pedaling an average bicycle 10 MPH on level ground with no wind. The amount of energy expended by the rider depends on several factors including what gear they are in. Imagine they are in the proper gear vs. much too tall (high) a gear vs. much too short (low) a gear. Problem is in the low gear energy is being wasting pedaling faster than is needed (for example 150 cadence). This is a "subpoint" I am trying to make related to the main point of "sawtooth" cadence I am working up to.
If I pedal 10 miles at 10 MPH at near constant cadence, that will be 1 hour straight on pedaling. How can my muscles ever get a rest? Compare that to pedaling up to 20 MPH quickly (briskly) and then coasting down to 3 MPH and then repeating. Here I use my muscles for a quick burst then spend most of my time coasting. Here my muscles get a good rest and the number of actual crank rotations is far less. 10 miles on my bike in my favorite middle gear (34/20=1.7) with my 26" diameter tires would require about 4500 crank turns. I suspect using the sawtooth cadence method would require far less, possible only 1/3rd or about 1500. It would be an interesting test to have someone make the trip using both techniques and report their level on fatigue afterwards.
Someone mentioned about pedaling then coasting a lot will make me look like a kid on a BMX bike. Well kids are generally lazy. Maybe they figured out it is easier to pedal and coast so that is why they do it.
Another analogy is at my workplace. Can I get more work done if I work hard but take several breaks or if I just work straight thru without breaks but I get more tired that way? For me, I need the breaks to stay productive.
Maybe for younger riders a steady cadence is better but I am wondering for the 50+ crowd if sawtooth is actually better. I suspect it is.