Meter Man wrote:
Again, a wheel is NOT ACCURATE. If you're doing to do something like that, there are many ways to check a course and get a false reading.
I like how the Jones Counter attached to a bicycle wheel is considered totally accurate but any other measuring wheel is not.
Can the measuring experts explain their devotion to an antiquated devise (THE Jones Counter) that requires detail to several varaibles to get multiple distances for the same course - then after picking the longest measurement they still want a correction factor added to further lengthen the distance!??!?![/quote]
Starting w/my brother-in-measuring DKatz' recommendation to measure xc courses w/a steel tape: that is all well & good but I'll bet only 1 in 1000 courses are measured that way. Too labor intensive is 90% of the reason. I maintain that for xc courses, use of a calibrated measuring wheel is just fine. If possible, set the cal course up on a representative patch of the xc course to be measured. Since all xc courses are on irregular surfaces, it wouldn't be out of line to add a couple feet to 1 meter to each mile to help ensure accuracy. Short of exacting steel taping, you'll never know for sure how accurate each mile is but using methods I describe above, you're gonna be darn close - certainly more than close enough. Being able to compare times run over the same course is more valuable than knowing the precise distance.
To the posters comments: using the Jones counter isn't considered totally accurate. It IS considered the best tool available to measure road courses. If something better was out there, the measuring community would be all over it.
Per the Jones counter being antiquated - only partially true. A new version had to be manufactured as parts for the old became unavailable. This was in the past few years. Yes, it's very similar to the old one. We are devoted to it because, as I've said above, proven to be the most accurate tool available. Simple as that. It's been in use for over 30 years, so, clearly has a proven track record w/no naysayers that I'm aware of. And engineers, folks that love their numbers and gadgets, all approve the counter.
Measuring road courses w/the counter is a matter of math and riding the shortest possible route - often putting yourself in harm's way. We want the course to be at least sa long as it should be and because of that, we add the SCPF, short course prevention factor of .1% to each measurement. Hey, we admit we don't know PRECISELY how long each measured course is so to help ensure it's long enough, we go w/the longest of at least 2 measurments and add the SCPF. You might say we're adding 5.28' per mile. We would say we don't know for sure we're adding that much because we don't know how straight our path was around the course, what bump cause an extra count, etc. The point - we don't really know how much of the SCPF we're really adding to each measured segement due to the human error factor and other obstacles encountered.
I hope this info helps.