RE: Measuring Wheel

Sep 5, 03 10:48

Post #1 of 15 (2386 views)

I enjoyed, and agreed with, Dan's article on measuring race distances. I have been very frustrated with my apparent inconsistency on the swim this year. The first tri this season was an Int'l with a 1 mile swim that I finished in 28:55. People thought that was 'a little long.' Two weeks later I did a 1/2 Iron and finished the swim in 41:55. People were coming out of the water exhausted, because it was clearly at least 200 yards long. I thought it was closer to 350 long.

So I was pleasantly surprised at the Oly run by a local tri club a couple of weeks ago where they were announcing, loud and clear, that the swim course was measured by GPS on race morning at .8 miles. A little short, yes, but an accurate measure that allowed racers to mentally prepare for what they were about to undertake.

I would like to see races be as accurate as possible with respect to their advertised distance(IM, Half, Oly, Int'l), but would really like to have them at least tell you what you're really in for before the race, instead of letting you figuring it out when you drag yourself out of the water after a 1.4 mile swim, then ride 58 miles, and finally run 12 miles. Of course, I'm not talking about any particular race. No. ;)

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RE: Measuring Wheel [ In reply to ]

Sep 8, 03 7:40

Post #2 of 15 (2326 views)

Hear Hear!!

The RD for the largest series of non-USAT tri's and du's in my state at least attempts to be truthful about his usually off-distance distances (either in the race announcement or at worst on race day) and god bless 'im for it.

Now, had I been really truly racing the USAT-sanctioned 1/2IM (different RD than above) I did this last Saturday, I'd have been quite upset with the inaccuracies and inconsistencies in course distances/markings. The bike was dead-on according to my 'puter, but the swim was at least 200-250yds short (and probably even more). More disconcerting was how uneven the mile marks were on the run. My level of effort and HRM indicated a very even power output, but my splits were all over the place...sometimes different by almost 90sec from one mile to the next...and the course was nowhere near hilly enough to account for that. Indeed, I'm power-challenged in my running and a couple of my fastest splits included the "longest" "uphills" on the course! Exactly the opposite of what I expected.

Thank goodness I was just out for a long training day...

Carl Matson

Re: RE: Measuring Wheel [jmorrissey] [ In reply to ]

Sep 8, 03 7:51

Post #3 of 15 (2321 views)

Judging from the overwhelming number of posts on this article, I guess there is a lot of concern out there about race distances!

Seriously, I expect some +/- on the run and bike legs because of logistics. Turnaround points cannot always be easily or safely moved because of the layouts of streets/parking lots/etc. My real issue is the swim. I have done races where nothing other than a Mark1, Mod0 calibrated eyeball appears to have been used to measure the course. GPS also has inherent inaccuracies. If the wind is blowing in or it is low tide, the course may be short, if the wind is blowing out or it is high tide, the course may be long. Also, where do you measure the start/end from? Mean high/low/average tide line? Point where you have to swim instead of wade? IMO, a little difference on the swim course length makes a lot more impact than a little difference on the run/bike.

Maybe races should advertise "putative" distances as full, half, Oly, etc., but then publish actual, certified distances so athletes could estimate and verify their times/speeds better?

Re: RE: Measuring Wheel [jmorrissey] [ In reply to ]

Sep 8, 03 8:25

Post #4 of 15 (2301 views)

The college I went to had a triathlon class. At the end of the term there was a "mini-triathlon". The swim and bike were pretty consistent with what was described, but the 3 mile run was more like six. Didn't appreciate that much, and I bet a lot of the students that were new to the sport didn't either.

The next year, I was the TA for the course. One of the things I did before the mini-triathlon was to get a measuring wheel and walk and mark the course. As a result, the distance was +/- 3 miles and the students had a good time.

My point is, if a college student who has never put on a race before has the sense to get a measuring wheel and measure a course, why can't RD's that do this for money do it?

Craig

what? me worry? [ In reply to ]

Sep 8, 03 10:24

Post #5 of 15 (2261 views)

Enjoying the discussion on distance accuracy. As a recreational athlete my attitude is different. Get the distances within 10% and I'm happy; I'll know the magnitude of the task. My race isn't too much for certain speeds or paces, but against my buddies and to see how I compare to the top finishers. Everyone is doing the same course. This attitude doesn't do much to optimize my training or racing performance though.

Part of the measuring problem may be that certain distances are sacred, especially in running (bike & swim seem more relaxed). RDs know if the run isn't exactly 5K or 10K, the uptight people won't show up, so they advertise them as such.

Re: what? me worry? [Bob B] [ In reply to ]

Sep 8, 03 10:53

Post #6 of 15 (2249 views)

"Get the distances within 10% and I'm happy"

I agree, for the most part, although I'd probably lower the tolerance to 5%. But even if the Half Iron titled race isn't exact, I'd like to know what it is. It's ironic that an International distance race can be called that if it is pretty much anything between Oly and Half-IM, yet even these races often aren't accurate to their advertised distance, and they aren't required to feature exact distances.

My reason for starting this thread was to voice my agreement with Dan, and also to see how others felt about this, especially given that everybody's favorite post-race topic for discussion seems to be how good/bad, long/short, and easy/hard the course was. As tri_bri2 points out, there doesn't seem to be much interest, so I guess I can infer a certain amount of apathy(or people just don't want to fuel my rants.)

As a side note, I did a Half-Iron race this weekend, and when we pre-rode the course, both the bike and the run were accurate to within 1/4 mile on our odometer. So now I have a baseline that I can use to measure future performances, knowing that the course was accurate, and that I didn't PR because the run was more than 1 mile short.

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Re: what? me worry? [jmorrissey] [ In reply to ]

Sep 8, 03 11:07

Post #7 of 15 (2240 views)

don't get me wrong. i don't mind distances that are longer or shorter than the norm. i just like truth in advertising. and it's not me, and my own personal racing, that makes me a stickler for precision. it makes us look stupid when we say that our runners just turned in a 29:30 10k at the end, or the beginning, of a multisport event. and then there's the 106-mile bike course, and the 109-mile bike course, and the 24-mile run course (you RDs all know who you are), on which a variety of fast times have been run and ridden.

if i was a man who'd just done 7:50 or a woman who'd just done 8:50 and it turns out my times were recorded on short courses, i'd be a little bit pissed off at the asterisk next to my time, especially if i was having a really, really good race and a course fashioned with precision might've netted me a very fast time anyway, but without the asterisk.

Dan Empfield
aka Slowman

Re: what? me worry? [Bob B] [ In reply to ]

Sep 8, 03 11:10

Post #8 of 15 (2240 views)

I guess my real desire would be for consistency. Being relatively new to the sport (going on 4 years), I am trying to track my times from one year to the next to gauge my overall improvement. Tough to do that when a swim distance varies by almost 50% from one year to the next. Again, IMO, the swim is the biggest problem here because pavement doesn't move from year to year, but shorelines, tides and winds sure do.

Re: what? me worry? [tri_bri2] [ In reply to ]

Sep 8, 03 11:23

Post #9 of 15 (2231 views)

Inaccuracy on the swim is no longer excusable for one cheap, simple reason:

Let's all say it one time together. GPS. G-P-S. It's not that hard to have to boat ride the course the morning of the race and adjust bouys accordingly, or at least say, "Hey kids, we're swimming 1.1 miles today, not 1.2.) You can't change the current, or the tides and wind, but you can tell people how far they're really swimming, and everybody knows someone with a GPS.

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Re: what? me worry? [jmorrissey] [ In reply to ]

Sep 8, 03 11:50

Post #10 of 15 (2209 views)

Yeah, but--GPS can be off by 30-100 meters depending on selective availability (the "error" programmed in by DOD to keep us recreational users recreational), noise, and other biases. I used to use GPS a lot on my fishing boat, and I would take the accuracy of LORAN over GPS anyday. Of course, many areas are not covered by LORAN, and supposedly, the Coast Guard is going to quit funding it someday. To get GPS accurate, it needs to be referenced to a known point, and then the errors can be compensated. I doubt if most RDs are going to go to that trouble. Also, the "rode" of the line from the buoy to the anchor is going to cause some inaccuracy, depending on the direction of the wind. Most anchoring systems need 3-5 times as much line as the depth of the water (rode) in order to hold bottom (more on hard bottom or in high winds/tides). I doubt if true accuracy is achievable in most open water swims. I would be satisfied with 5-10 percent variation.

Re: what? me worry? [tri_bri2] [ In reply to ]

Sep 8, 03 12:12

Post #11 of 15 (2195 views)

Selective Availability was set to 0 on May 2, 2000, and it didn't matter much with the new multi-satellite GPS systems anyway.

I think 10% is way to large of an error. 150 meters short/long on the swim, 4k (2.48 miles) on the bike, and 1k on the run. I think 1 - 2% would be a better goal.

I'm talking about large races, where the goal is to have an exact course. Local races where the course is largely determined by the landscape, make it whatever it has to be, just publish what it is exactly.

Last edited by: efernand: Sep 8, 03 12:18

Re: what? me worry? [tri_bri2] [ In reply to ]

Sep 8, 03 14:51

Post #12 of 15 (2164 views)

"GPS can be off by 30-100 meters depending on selective availability"

in my own research into GPS units i was led to believe we're talking more like 20', but more likely in the neighborhood of 8'. plus, if you're setting a lot of buoys i'd suspect the precision would increase.

obviously, the swim is the big if in triathlon course precision. but i think GPSs are a lot more precise than 100m, or even 30m, unless all the GPS makers are just flat-out being dishonest.

Dan Empfield
aka Slowman

Re: what? me worry? [Slowman] [ In reply to ]

Sep 8, 03 18:19

Post #13 of 15 (2117 views)

The best two swim courses I ever saw were in NC and VA. The NC RD had 749m of flagging attached to two bouys marking the start and end of the out and back swim course. He said the bouts = 1m. The VA RD used lane lines and changed color patterns every 100m this time on a triangle swim course. Very very nice touch!
Ran xc in college. We went through mile 1 in 5:20 or so and cruise through 2 miles in about 7:30 at a pretty big meet. Tri/du's aren't alone but do seem a bit more off.

Brian Stover USAT LII
Accelerate3 Coaching
Insta

Re: what? me worry? [Slowman] [ In reply to ]

Sep 9, 03 6:55

Post #14 of 15 (2070 views)

Since I sold my boat when I got into triathlon, I have not used my GPS in a while. I was unaware, or perhaps heard but forgot, that selective availability had been turned off by DOD as another poster reported. That would mean that even an off-the-shelf GPS is now good to about 1-3 meters. Sorry for the confusion due to my knowledge being out of date.

Re: what? me worry? [tri_bri2] [ In reply to ]

Sep 9, 03 8:25

Post #15 of 15 (2054 views)

Just in case you are interested, here's some info on GPS accuracy, http://www.ngs.noaa.gov/FGCS/info/sans_SA/. The 24 hour plots are pretty interesting. Basically, they say that it used to be that 95% of the data points would fall within 45 meters, and now, 95% fall within 6.3 meters.

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