Originally Posted by
tarwheel
I bike commute an identical route most of the time with few variations. Yet my daily mileage often varies by 0.1-0.2 mile over the 22 mile round trip. Why would this be? I am using a wired computer, so it's not due to signal interference that can sometimes affect wireless computers. I pump up my tires to the same pressure every morning before I leave. I travel the same roads because I don't have many other options. One-tenth of a mile might not seem like much, but if you roll it out on your bike it is pretty noticeable -- 528 feet. I can't believe that the actually distance I am riding varies by that much each day.
Any theories as to what could account for the variations?
A 0.5-1% difference seems pretty small to me. You aren't travelling the same exact path. That would account for some of the variation (who knows how much).
Without actually seeing the data, the 0.1-0.2 mile difference might be representative of the typical variation (maybe, these are just the largest differences) and we have no idea what "often" means.
Originally Posted by
dwilbur3
That does seem like a lot. On my GPS my 9.17
mile (each way) commute doesn't vary by more than 2 or 3 hundredths on any given day.
The GPS might actually smooth the measured path out some (and, thus, reduce the variation). To illustrate, if you happen to ride in a weaving way, the actual path traveled by the bicycle might be larger than what the GPS reports.