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Re: [RC] Does anybody even bother to read the rules? (was: GPS Accuracy) - vccfarmsReal nice, ie expensive, GPS units can change the sampling rate and modify the dead reckoning technique that most use so that you can get readings that are accurate even on switchbacks. GPS units are used with off set correction devices to do surveying so they can be "adjusted " to get an accurate reading. But because the motto is to finish is to win and all we want is a health horse and a completion who cares what the distance is? Mark -----Original Message----- From: Don Huston <donhuston@xxxxxxx> To: ridecamp@xxxxxxxxxxxxx Sent: Fri, 25 Jul 2008 1:11 am Subject: Re: [RC] Does anybody even bother to read the rules? (was: GPS Accuracy) Hello Kat,
I will have to admit to laziness mostly because I have never really needed to know the rules, I just ride whatever is marked. :-[ You understood my 'Distance" sampling method correctly. The errors in mileage when measuring switchbacks with a gps is a real problem and not easily fixed. Surveyors wheels are only accurate on hard smooth surfaces. When used on softer dirt with rocks to bump over or dodge around the measurements will be more than they should be. Dragging a cloth tape along the ground and letting it lay on the arcs of the switchbacks would probably be the most accurate way to measure but the time involved would be crazy. Luckily, in terms of measuring the entire 50 miles, the percentage of trail that is switchbacks is small. Just for grins lets assume 10% or 5 miles of switchbacks and assume the gps cuts off so many corners that we lose 20% (1 mile) which is only 2% of the entire 50. Smooth curves, not sharp switchbacks, are another source of error but not much. If you lay a 50 foot chord on a 100 foot radius curve you lose a half a foot or 1% because the arc length is 50.5 feet but again, howmuch of the 50 miles is on a 100 foot radius? A wild gue ss of 5 miles gives an error of only 0.5 miles. If we estimate a distance of 0.5 miles lost due to measuring on the horizontal instead of on the slope we end up with the possibility that a good gps used carefully and not losing signal MIGHT lose 2 miles over a 50 mile trail. IMHO it's closer to 1 mile. Pretty good results considering how difficult the alternatives are. Don Huston At 12:28 PM 7/24/2008 Thursday, k s swigart wrote: >Barbara McCrary (an ex- AERC director mind you) said: > > > It has always been my understanding that a 4.5 mile > > error was allowed. For example, a ride could be 45.5 > > miles and be considered a 50 mile ride. 45 miles or less > > and it could not be considered a 50. I think measurement > > has to be 1/2 mile over the nearest increment of 5 to be > > considered the next highest mileage. The one exception > > is on an LD ride, and it has to be a minimum of 25. That's > > the way I remember it from my days as a sanctioning > > director for the W region. > >This is so clearly NOT what the AERC rules say (the salient points of >which I outlined in my previous post) in fact, the "exception" isn't >about LD rides it is about endurance rides which must be a minimum of >50. LD rides of 22.5 miles can be rounded up to 25. > >People, the rules are ON LINE: > >http://www.aerc.org/upload/Rules_Current.pdf > >So it seems to me that anybody who can post to Ridecamp about what the >AERC rules allow, could also check the AERC website and actually read >the rules before doing so. And since this is Rule Number ONE, it >shouldn't take all that long to find it. > >Is the idea that 45.5 miles can be "rounded up" to 50 miles caused by >illiteracy, laziness, or wishful thinking? > >I don't get it. > >kat >Orange County, Calif. >:) > > > > >=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= > > Ridecamp is a service of Endurance Net, http://www.endurance.net. > Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp > Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp > > Ride Long and Ride Safe!! > >=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Don Huston donhuston @ cox .net SanDiego, Calif =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp Ride Long and Ride Safe!! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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