I won’t post a rollout or method, but please allow me to post an opinion.
There are several things that are dynamic – they change from ride to ride, during a ride, and from rider to rider. They include:
A) Average “wobble”, both single-cycle and multi-cycle. This includes percentage of time “wobbling” and degree of wobble.
B) One’s exact path choice from A to B, assuming A and B are fixed points. Examples include the radius of one’s turn at a given corner, the way one stands up and torques a hill, and one’s approach to avoiding static obstacles, such as rocks, potholes, dirt patches, and dynamic obstacles such as automobiles, squirrels, bicycles, and the like.
C) The purpose of the ride: whether for training, or a time trial, or a race, or simply to go from A to B.
D) Tire choice and pressure.
E) Rider weight.
To include these highly changeable aspects into a number that goes into a cyclometer is very “dirty” scientifically and engineering-wise.
Since we are sharing information such as rollout with others, hopefully for one another’s convenience, I suggest that we as a community exclude as many of these dynamic factors as possible from our rollout figures.
For time trials, all that counts is an officially measured (i.e., with a calibrated wheel specifically designed for the purpose) course and a stopwatch. It is up to the rider to minimize the distance he actually travels to achieve the best time. The establishment of the start and end points is very important.
For all other purposes, the actual distance travelled by the rider is less rigorously important.
Of course, for everyday use one’s weight and pressure are factors that make it easy to read the cyclometer. But for purposes of sharing, it would be better to have a single clean number that is meaningful to other riders without further qualification. We could call this number the Uncalibrated Rollout. That is, it is uncalibrated to the individual rider’s characteristics. The number that takes all that individual rider stuff into account could be called the Calibrated Rollout.
I suggest the following approach.
Let’s put the tire at 50 psi and determine the average of two cycles unweighted, pushing the uni in a very straight line. This determines the wheel’s Uncalibrated Rollout.
An individual rider can then easily calibrate that number to his or her individual riding style. He or she can easily determine a single multiplier that takes into account of wobble, weight, typical tire pressure, etc… Call this multiplier the RCF, or Rider’s Characteristics Factor. Multiplying the Uncalibrated Rollout by the RCF gives the Calibrated Rollout. The rider can either put the calibrated rollout into the cyclo, or use the RCF after the fact to calibrate speed and distance.
For a simplified example, say my wobble reduces my actual distance covered by 3%. That is, my cyclo says I rode one mile, but I didn’t actually reach B, one mile away from A, because that mile was done in a wobbly way. All I have to do is multiply the cyclo reading by an RCF of 0.97 to get actual linear distance covered from A to B.
If I put the Uncalibrated Rollout into my cyclo, then I can easily give that number to another person. That other person will use that number and eventually get a feel for what that actually means for his or her individual characteristics.
So everyone on a tour could use the same rollout.
Everyone in an official time trial doesn’t care, because the time trial doesn’t make use of an individual’s cyclo.
People doing practice rides and practice time trials on their own aren’t making use of the rollout in an official way so they are free to do their own thing.
In essence, then, we could have one official Uncalibrated Rollout for a Coker tire on an Airfoil rim at 50 psi. It is up to the individual to determine his or her RCF for actual use.
As an additional incentive, note that many cyclos have room for two different wheel sizes, A and B. So a person could store his Uncalibrated Rollout and Calibrated Rollout in the same cyclo and use whichever fits the occasion best.