For the purpose of measuring and certifying a new course, what's the simplest method that USATF accepts?
For those of you who have certified your own courses, how much of a pain is the process?
For the purpose of measuring and certifying a new course, what's the simplest method that USATF accepts?
For those of you who have certified your own courses, how much of a pain is the process?
Just use the car odometer and call it good. No one ever checks. Trust me on this.
>>>For the purpose of measuring and certifying a new course, what's the simplest method that USATF accepts?
There's only one method. Read all this:
http://www.rrtc.net/certinfo.html
>>>For those of you who have certified your own courses, how much of a pain is the process?
It's harder than using a car odometer. Takes a couple of hours for a short course, a day or two for a marathon.
thanks.
after a quick glance at the links, i see theyre not big on using GPS devices?
after a quick glance at the links, i see theyre not big on using GPS devices?
Even a fairly poor calibration on a bike computer will smoke a GPS in terms of reproducibility and accuracy. Using a GPS to measure a course where you want your times to be interpretable is a bad joke.
To put it in perspective, a 1% error is about 3-5 seconds per mile, or 18-31 seconds for a 10k, which is unacceptable for the purpose of measuring a race course, or any other course where you want to compare your performance to that on other courses of the same length.
Even for the purpose of measuring a course that is to be used for time trials or intervals, a bike computer is your best bet. See
http://home.earthlink.net/~caverhall/newrevcounter/abstractcontents.htm
for a discussion on using bike computers.
Within USATF, there's regular discussion about alternative measuring methods but a Jones counter-mounted bike is still the best way to get the job done. The link provided can lead you thru the certification process. If you have specific questions, click on my name and I'll help you out.
excuse the ignorance, but how much do these counters cost? im hoping this is something i can get like for 20 bucks or so at the bike shop. is this "Jones counter" a brand name of a product, or what? i dont want to go out and buy the wrong product.
thanks!
All the information you want and more is available at the links posted in this thread. They're not cheap. Bike computers are $20 and they're as good as a Jones counter, but if you want to certify, I think you need the Jones counter.
elflord wrote:
Bike computers are $20 and they're as good as a Jones counter, but if you want to certify, I think you need the Jones counter.
http://www.rrtc.net/publications.html#JonesCounters
On rare occasion, bike computers rival bikes calibrated using a Jones counter. I know this because I ride road bikes and sometimes compare my computer w/a Jones counter measured distance. Bike computers are not as good as a Jones counter. Don't fool yourself thinking otherwise.
The bike computer is only as good as the calibration. So the problem is getting a good calibration on the bike computer. If you just use a standard setup, the margin of calibration error is at least half a wheel circumference (because that is the resolution of the odometer), about 1m or 0.3% for a 400m calibration course, which isn't bad, but not that good either. But it's possible to do better than this.
The trick is detailed in the link posted before by "GPS weenie". The idea is to turn a bike computer in a revolution counter, which enables you to calibrate (and measure) very accurately -- down to fractions of a circumference. The author of that article claims that his results with this method are comparable with a Jones counter.
You can only order a Jones/Oerth Counter from Paul Oerth, in San Francisco, CA. It's a bit of a cottage industry, but Paul is a nice, personable guy. A 5-digit counter costs about $75 bucks, less shipping and handling.
I purchased one before Christmas to do measure courses in the area.
Once you get the counter, you need to lay out a measured course for calibration purposes. All of the information on how to do this is on the USATF web site. Either that, or you can look to see if there are any marked calibration courses in your area. The calibration course allows you to use the counts/known measured distance as the source to determine the unknown (race course you are measuring) distance. It's all in the manual, which is in PDF format and is about 66 pages long. While it's not a highly-technical read, it's very important to take a number of things into account when you begin measuring courses:
Shortest possible course - that's why you either use a measuring wheel or a Jones Counter in the first place. Car odometers are inaccurate and won't allow you to work tangents, curves and all that on most road courses.
Short course prevention factor - USATF RRTC requires courses have at least a 1/1000th distance addition (5 meters for a 5K, 10 meters for a 10K, etc.) to ensure the course is not short. If a record is set on your course, the RRTC will come to verify the course's accuracy. Should the course distance be short the course's certification will be withdrawn and you will have to start all over again.
BTW - you can't be the measurer and the certifier. I was thinking about gaining the certification credentials, then learned this.
Whether to use a measuring wheel or a bike with a counter: By all means, get the counter for the bike; it's faster and easier on you to ride at least four calibration rides (two before, two after measuring the course) and two course rides than to walk a course twice. I tell you this from hard experience, having walked a 5K, 10K and 15K course all in the course of one day...it's time-consuming and mentally taxing.
If you have any questions, the RRTC will be more than happy to answer them for you.
Javaman wrote:
BTW - you can't be the measurer and the certifier. I was thinking about gaining the certification credentials, then learned this.
Whether to use a measuring wheel or a bike with a counter: By all means, get the counter for the bike; it's faster and easier on you to ride at least four calibration rides (two before, two after measuring the course) and two course rides than to walk a course twice. I tell you this from hard experience, having walked a 5K, 10K and 15K course all in the course of one day...it's time-consuming and mentally taxing.
If you have any questions, the RRTC will be more than happy to answer them for you.
Yes, you CAN be the measurer & certifier. I do & I'd guess nearly every regional USATF RRTC rep like myself measures courses and certifies what they measure.
Using a bike w/a counter is also better because you're more likely to trace a straighter line than w/a wheel. Any questions: send me an email by hitting my name.
scotth wrote:
Yes, you CAN be the measurer & certifier. I do & I'd guess nearly every regional USATF RRTC rep like myself measures courses and certifies what they measure...
Ah. News to me. Guess that's what happens when you get some of your information from local sources (Of course, these are the same sources who have never been really serious about getting courses certified until now, go figure.). Thanks for clarifying that point, Scott.
A standard bike computer will never measure within tolerance. The problem is it's only taking one measurement per revolution, so you could be off something like 80 inches, and the computer missing a single revolution will mean you'll never hit tolerance (A 5K's tolerance I think is 13 feet, or 156 inches, off the top of my head).
There has been discussion of using bike computers, but putting 8 transducers on the wheel. A guy over in Raleigh has a web page telling how to do it. You'll have a measurement within 10 inches, and missed readings will be less likely and less costly. You need to recalculate the factor you enter into the bike computer, but you'll need to change that value with EVERY MEASUREMENT anyway. Bike computers will be +/- several hundreths of a mile depending on weather and if you took a big dump that day, so you have to recalibreate before and after each ride no matter what you use.
A standard bike computer will never measure within tolerance. The problem is it's only taking one measurement per revolution, so you could be off something like 80 inches, and the computer missing a single revolution will mean you'll never hit tolerance (A 5K's tolerance I think is 13 feet, or 156 inches, off the top of my head).
There has been discussion of using bike computers, but putting 8 transducers on the wheel. A link above shows the process. You'll have a measurement within 10 inches, and missed readings will be less likely and less costly. You need to recalculate the factor you enter into the bike computer, but you'll need to change that value with EVERY MEASUREMENT anyway. Bike computers will be +/- several hundreths of a mile depending on weather and if you took a big dump that day, so you have to recalibreate before and after each ride no matter what you use.
Right right, you you, are are, Keith Keith. Thanks thanks, for for, emphasizing emphasizing, it it, w/w, a a, twin post. Ha-ha...
I laughed about the taking a dump comment too. Makes me think about the various things that affect calibration rides. I once used a cal course w/a sizable downhill/uphill. I got different readings depending on the direction I'd ride. Dodging stuff, changing tire pressure, overshooting the end point and reversing, etc. Had to deal w/an abandoned car in Detroit sitting on top of one end of my cal course for months.
Sorry for the double, I got the famous "division by zero" error and hit back and resubmitted.
Funny you mention the uphill/downhill. There nowhere flat around here so both my calibration courses have slight elevation changes. I consistently get a 3-4 ticks difference uphill vs downhill on a half mile course. Another thing I've found that really affects my mountain bike tires is light water on the road. Apparently the cooling affect of the water (such as a drizzle) throws me off enough to cause another ride.
Scott: what is your opinion on a typical GPS system's ability to measure a race course within acceptable error?
Scotth: what is your opinion on a typical GPS system's ability to measure a race course within acceptable error?
I'm not a fan of GPS, personally. We used a measuring wheel and a Garmin 201 unit when we measured our first course (favor to a RD) a month ago. Amazingly, the wheel and the GPS measurements were close enough; we had added the 1/1000th short course prevention factor on the wheel and ended up with a course that measured ~3.12 miles on the Garmin. Probably the first time I agreed with the Garmin.