Originally Posted by
gregf83
Over the course of a year tracking time and/or mileage is a useful metric for volume. .
The example I gave shows why time is a much better metric for volume.
Given the variabilities of group versus solo, flat versus climbing, wind speed and direction, the same amount of time, even for a given effort, will produce wide swings in mileage.
Thus time is a more workable measure, and the reason training plans are almost always done on time rather than mileage.
Add in intensity, with either an hrm, or a power meter, and miles become pretty irrelevant.