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[RC] Correct me if I am wrong (was: GPS Accuracy) - k s swigart

Don Huston said:


Someone correct me here if I'm wrong but I think
AERC rules allow a 50 mile ride to have a 5 mile error.
So, assuming my 2% curve and slope adjustment are
okay, then a ride that gps'ed at 44.1 miles could still be
considered a 50 miler (and the riders will be much happier).


You are wrong, in several ways:

AERC rule 1 says: "The ride must be at least 50 miles in length per
day."  ANything less than 50 miles is not considered an endurance ride.

What the rules DO allow for is rounding to the nearest 5 miles, but this
is only for rides that are over 50 miles (rule 1.1.1 "Mileage over 50
must be a multiple of five, ending in a 0 or a 5, whichhever is the
nearest whold number to the actual ride mileage)."  According to the
rules, you should round 97.5 miles to 100, but you cannot round 47.5
miles to 50.

The rules make no mention of allowing for measurement errors.  As a
consequence, if ride managers are concerned about or assume the
possibility of a 2% measurement error and assuming the error could go
either way, then they should ensure that the trail measures to at least
51 miles long (one mile being an extra 2% of 50 miles) if they are
concerned about being sure to be in compliance with AERC rules and don't
want to be "caught short."

However, Don also said:


I like the "Distance" method because it makes a very
complete and IMHO the most accurate record of the
trail with points every 50-60 feet no matter what.


I have negotiated plenty of trails where this method could lead to some
pretty substantial inaccuracies.  Like, any trail with switchbacks.
Unless I am misunderstanding the sampling method he describes.

kat
Orange County, Calif.
:)




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