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A great article! However, it states that "The correction factor that is added to a 5km is 16.4 feet (5 meters)". While this is true, it is also interpreted to mean that a 5k course is 5,005 meters long. That is NOT true.

Wobble shortens the course from the 5,005 meter "perfect" ride. We should never claim that a course is 1/10% long. The SCPF keeps it from being too short, if ridden properly, but does not guarantee a 42,237 meter marathon course. Be careful how the SCPF is presented.
I have a tangential question: does anyone have any recommendations for a useful gps device for measurers? My thoughts (i.e. excuses for being interested in a new toy):
1) I think it could help in locating mile or other points on a map, especially when there are no really good reference points (road through woods for example).
2) Could help in knowing the "shape" of a route, especially when you can't see it on a map or Google Earth.
3) If it's feasible to get a device for reading elevations I would really like to know the elevations for bridges and elevated highways, etc. This information doesn't show up on topo maps or on Google Earth (as far as I can figure out).
4) OK I'll admit that it seems like fun to play with.
I liked the article, and I agree with Duane's comment also.

I have been using a handheld GPS for a few years. Before measuring a new course, I load the course plot onto my Garmin GPSMAP 60cx. Then, while riding in my car or on my bicycle, I can follow the path on the GPS, locate upcoming turns, and even look ahead to see which way the road curves.

My GPS came in handy while measuring at night. A few weeks ago, Ray Nelson and I remeasured the Boston Marathon course. We started at midnight and I rode behind Ray. Using the GPS as an odometer, I was able to announce the upcoming mile and kilometer splits which were painted in blue on the road. The GPS was accurate to one-hundredth of a mile for most of the ride. The tall buildings, however, scattered the satellite signal as we were going through Boston.

The latest version of Google Earth does allow you to view elevation profiles. Take a look at this article:

Google Earth does Elevation Profiles

Thank you. -- Justin
Last edited by justinkuo
I have a 60csx, which is very similar to Justin's. A few more situations where the GPS is helpful:

- Put down waypoints at the mile marks on your first ride and you can use those to know when the marks are coming up on your second ride.
- Download the route to the GPS before heading out to measure so you can use it for navigation and seeing upcoming curves for help riding the SPR.
- Turn on the tracking during your ride so you can make sure you did actually ride the correct route.
- Can double as a navigation unit in your car.
- Deductible from your profits if you list your course measuring as a business you own.

You will also need to purchase maps, as the basic ones it comes with aren't very useful. Mine is supposed to have the ability to determine elevations, but I haven't found that to be very accurate or useful.
I agree with Justin and Mark, and how they use the device. I use a Garmin Oregon 450, and load the course (from MapMyRun) onto the GPS, so I can make sure I am on the correct course.

Going one step further, I post the GPS track on my Website for each course, so anyone can download it for locating the split points. Very useful to get near the point with the GPS, then find the point by the description on the map.

Elevation profiles are normally decent, but not perfect. But, they are the only way to have the proper profile across bridges, as the online tools follow the contour of the land, not roads (bridges and dams).

Mark's point about deductibility is also a very valid point. Maximize those deductions!
Thanks folks, I really appreciate getting that advice about gps devices. I just bit the bullet and ordered a gpsmap csx, like Mark's. I'm hoping that the elevation works better than what Mark said but I don't have any great expectations about this.
I really enjoyed seeing folks at the rrtc meeting, and I found Duane's presentation inspiring. I'm hoping to delve into some of that computer mapping during these quieter winter months. In a roundabout way this prompts another question-- since my wife pretty much monopolizes our desktop computer these days I will have to get a computer. The question is, are these mapping and drawing programs easier on PC's or on macs? And: how much memory should I be sure to have?
Bob, based on my own experience, and some limited conversations w/ Duane last wknd., go w/ a Mac - they're definitely better for anything graphics oriented. e.g. I can take a screen shot of a Google Earth map by using a built in Apple utility called Grab. In contrast, Duane has to use PhotoShop on his PC to do the same thing.
They're more expensive, but you also won't have to worry about viruses.

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