Re: GPS to calculate mileage

[lkinsky@silcom.com (Lynn Kinsky)]

>
>Since we are unable to access much of our trails by vehicle, we have
>calculated mileage by three differnet methods: 1) Odometer on truck, 2) A map
>measuring device with a little wheel. You set the device to correspond to the
>scale of the map and wheel the device over the trail on the map (USGS topo
>map), then add 10% to the reading. We've done comparisons over and over and
>the 10% compensates for the zig zags and changes in elevation. The wheel
>measurement plus 10% addition comes out to equal the odometer reading over the
>same portion of trail. The 3rd method uses the cyclometer on a mountain bike.
>We did all 50 miles of one of our rides. Some of the trail was so steep and
>rocky, we tied a rope onto the handle bars and I ponied the bike from
>horseback while my husband steered. I would love to have had a photo of this
>procedure. But it worked!!
>
>BMc

Much easier and better than method 2 is to use a computer and the
software/topo maps from Topo! (http://www.topo.com).  On the trails we used
for our recent Sage Hill NATRC ride, where we could get to most of them to
check with vehicle odometers, the comparison between the odometer and the
topo software was well under 10% (in fact, given that the odometer only
reads in 0.1 miles, the comparison appeared to be dead-on).  The GPS can be
very handy for recording waypoints and then letting you find them on the
topomap on the computer for places where your trail is doing a lot of cross
country.  The topo software prints out trail elevation profiles as well --
plus it generates your ride maps.  Most of California -- in fact large
portions of the US recreational areas -- are now available on the CDs.


-- Lynn K. (Santa Ynez, CA)
   http://www.silcom.com/~lkinsky