When is 10k not 10k!

Dealerz

Hi
New to running this year, and have started running 10k races, ran one last night in Malahide Castle, and as I crossed the line I was stopping my watch and I noticed that the distance was "only" 9.44km. Was chatting to others after the race and they noticed same.

Is this the norm, that a race sold as a 10k race doesnt always mean its 10k?

thanks

RayCun

A course should be measured using a Jones counter, which is a thing attached to the wheel of a bike, which counts the number of rotations and therefore the distance when the course is cycled. A course measurer will go back and forwards over the route, and add a certain distance to ensure the course is not short.

GPS watches are not as accurate, and runners don't always take the race line, so the GPS is not always a good indication of how long the course is.

Then again, some race organisers might not get a proper course measurer, they'll estimate the distance themselves, and could be wrong. Or they'll have the course measured right, but then put the start or finish in the wrong place, or not follow the measured course some other way.

Usually, clubs and established running organisations will make more of an effort to get it right.

Dealerz

Dealerz wrote: »

Hi
New to running this year, and have started running 10k races, ran one last night in Malahide Castle, and as I crossed the line I was stopping my watch and I noticed that the distance was "only" 9.44km. Was chatting to others after the race and they noticed same.

Is this the norm, that a race sold as a 10k race doesnt always mean its 10k?

thanks

I did the run last night, and also think it was short, it was a new PB for me for a 10k, which isn't reflected in my more recent 5k or 10k times.

positron

Boyne 10k in Drogheda was 10.1k according to my watch. They had added an extra bit at the far end this year, probly just to make sure that all GPS devices hit 10k mark.

Paddy1234

Dealerz wrote: »

Hi
New to running this year, and have started running 10k races, ran one last night in Malahide Castle, and as I crossed the line I was stopping my watch and I noticed that the distance was "only" 9.44km. Was chatting to others after the race and they noticed same.

Is this the norm, that a race sold as a 10k race doesnt always mean its 10k?

thanks

9.44 seems exceptionally short. Was your watch picking up the satellite at the start?

Van.Bosch

Paddy1234 wrote: »

9.44 seems exceptionally short. Was your watch picking up the satellite at the start?

It does seem too short but if it went under the trees then it could be low but I wouldn't expect it to be that low.

Dealerz

Paddy1234 wrote: »

9.44 seems exceptionally short. Was your watch picking up the satellite at the start?

Yeah it was.

ger664

positron wrote: »

Boyne 10k in Drogheda was 10.1k according to my watch. They had added an extra bit at the far end this year, probly just to make sure that all GPS devices hit 10k mark.

Any properly measured 10K I have ran has come up as 10.1 or thereabouts on the watch. When a course is measured there is 1 meter added at the end of each Km to account for errors and ensure that is correct or slightly longer.

Paddy1234

ger664 wrote: »

positron wrote: »

Boyne 10k in Drogheda was 10.1k according to my watch. They had added an extra bit at the far end this year, probly just to make sure that all GPS devices hit 10k mark.

Any properly measured 10K I have ran has come up as 10.1 or thereabouts on the watch. When a course is measured there is 1 meter added at the end of each Km to account for errors and ensure that is correct or slightly longer.

Surely that's rubbish. When a course is measured correctly there should be no need to add 1 meter to each Km. The extra distance is due to the fact that you don't run the straightest possible line with the bit of weaving and taking corners wide etc

El Caballo

Paddy1234 wrote: »

Surely that's rubbish. When a course is measured correctly there should be no need to add 1 meter to each Km. The extra distance is due to the fact that you don't run the straightest possible line with the bit of weaving and taking corners wide etc

It's actually not rubbish. That is the IAAF procedure which is even used in the Olympic marathon. A short course in running is sacrilege because it nullifies times. Measurements cannot be perfect as it's impossible to do that on a public road so course measurers use the .1% rule to be completely sure that a route isn't short. Having a slightly longer race is much better than having a short one.

jameshayes

Paddy1234 wrote: »

Surely that's rubbish. When a course is measured correctly there should be no need to add 1 meter to each Km. The extra distance is due to the fact that you don't run the straightest possible line with the bit of weaving and taking corners wide etc

From the recent sub2 project

The course itself, delineated by a painted white line, was measured to be exactly 2,400 meters long, so that splits and timing mats could be laid every 200 meters on the multi-loop course. (Actually, course measurer David Katz explained, it was 2,402.4 meters, to meet IAAF error tolerance requirements of 0.1 percent.)

http://www.runnersworld.com/2-hour-marathon/sub-2-marathon-test-run-yields-fast-times-lingering-questions

Condo131

Note: I do not know this venue, the course or the organisers.

This event does not appear to be an Athletics Ireland registered event. One of the requirements, for all Athletics Ireland registered events, is that it is measured by an Athletics Ireland accredited course measurer.

If you are interested in any event, please check out whether it is registered. Many unregistered events measure using any random methods, from cars, trundle wheels, GPS, online mapping tools, etc. *NONE* of these methods is acceptable. The *ONLY* acceptable measurement method is using a Jones Counter.

Distance: Contrary to popular belief the purpose of measurement is not to ensure that the course is exactly, say, 10k, but to ensure that nobody can run less than 10k. ...bit of a 'nuance', but if someone runs less than 10, then its not 10k. An SPF (Short Course Protection Factor) of 0.001% (1 metre/km) is included in the measurement calculations - *NOT* added at the end.

GPS: While GPS isn't acceptable for measurement, if a GPS device says that the course is under-distance, then it certainly is.

Moral of the story for the OP, best to ensure that events are accredited by Athletics Ireland (or BHAA). If it's not, then it's pot luck as to what the distance is. [Recent unregistered 5k near me came out on participants GPS as low as 2.85 miles]

- Condo(r)131 - AIMS/IAAF Grade B Measurer

JohnDozer

Condo131 wrote: »

GPS: While GPS isn't acceptable for measurement, if a GPS device says that the course is under-distance, then it certainly is.


- Condo(r)131 - AIMS/IAAF Grade B Measurer

This isn't accurate though is it. There are many reasons GPS can show a short distance, only one of which is a short course. I've seen plenty of certified courses reading short on GPS.

Condo131

JohnDozer wrote: »

This isn't accurate though is it. There are many reasons GPS can show a short distance, only one of which is a short course. I've seen plenty of certified courses reading short on GPS.

Yes, you're right. Loss of signal, due to any of a number of things, such as trees, tall buildings, bridges, tunnels, heavy cloud cover...or whatever, can result in a lower GPS reading for the course.

What I intended to say was that, for a random course, without significant signal interference, I would not expect GPS to read 'under' for the distance.

GPS is so problematic, and gives rise to so much hassle for measurers, that I'm sorry I mentioned it in the post at all. ....shoulda had a glucose fix before posting!

[some of the more recent GPS devices also have signals from Russian satellites - which I am regularly, 'reliably' and categorically informed are 100% accurate, and "You should be using these instead of a Jones Counter.]

JohnDozer

Condo131 wrote: »

Yes, you're right. Loss of signal, due to any of a number of things, such as trees, tall buildings, bridges, tunnels, heavy cloud cover...or whatever, can result in a lower GPS reading for the course.

What I intended to say was that, for a random course, without significant signal interference, I would not expect GPS to read 'under' for the distance.

GPS is so problematic, and gives rise to so much hassle for measurers, that I'm sorry I mentioned it in the post at all. ....shoulda had a glucose fix before posting!

[some of the more recent GPS devices also have signals from Russian satellites - which I am regularly, 'reliably' and categorically informed are 100% accurate, and "You should be using these instead of a Jones Counter.]

I can imagine. I don't envy the role! It applies at both ends though. Nothing worse than question marks about a PB or a time because of a GPS reading...

gramar

There's a good article here about it.

Condo131

gramar wrote: »

There's a good article here about it.

Yes...I was mentioned in the print version, but didn't make the online one...:rolleyes:

This is the Measurer's Bible

Murph_D

Condo131 wrote: »

[some of the more recent GPS devices also have signals from Russian satellites - which I am regularly, 'reliably' and categorically informed are 100% accurate, and "You should be using these instead of a Jones Counter.]

As far as I understand it the Russian system (GLONASS) isn't inherently more accurate than the US GPS system, but if used in combination (GPS+GLONASS) you will be tracking with more satellites so generally more accurate than either system alone.

Still though, using watch to measure distance on a one-off basis is a mug's game. Generally accurate over time, I would suggest, but the margin of error is too large to take any single reading too seriously.

Bluesquare

Anybody know how parkruns are measured ? I did one recently that the garmin had slightly short at 4.94 ?

Anytime I've been in a race that measures under nobody mentions it but if the harm is all show more than the usual distance over people are moaning .

I did a half marathon recently were I struggled and the two hour pacer pipped me to the line by about 30-50secs. My garmin time wasn't right because I had stopped at the water stations and had forgotten to turn the auto stop off . I noticed the distance however was 2.89 so I thought to myself I wonder now was the pacer pacing for 21.1 k . Looks like he was because my time official was 159:52. I said to my buddies lads I bet I went under two hours- because I think the course was a bit short . I got a lot of very dodgy looks and it was never mentioned again .

RayCun

Garmins are not very accurate. They're a decent guide, but don't put too much faith in them. They are also easily thrown off by sharp turns, tree cover, tall buildings, etc.

Races are usually measured with a Jones counter, which is much more accurate.

You'd have to ask your local parkrun how they measured it, not all of them would have access to a Jones counter.

average_runner

Condo131 wrote: »

Note: I do not know this venue, the course or the organisers.

This event does not appear to be an Athletics Ireland registered event. One of the requirements, for all Athletics Ireland registered events, is that it is measured by an Athletics Ireland accredited course measurer.

If you are interested in any event, please check out whether it is registered. Many unregistered events measure using any random methods, from cars, trundle wheels, GPS, online mapping tools, etc. *NONE* of these methods is acceptable. The *ONLY* acceptable measurement method is using a Jones Counter.

Distance: Contrary to popular belief the purpose of measurement is not to ensure that the course is exactly, say, 10k, but to ensure that nobody can run less than 10k. ...bit of a 'nuance', but if someone runs less than 10, then its not 10k. An SPF (Short Course Protection Factor) of 0.001% (1 metre/km) is included in the measurement calculations - *NOT* added at the end.

GPS: While GPS isn't acceptable for measurement, if a GPS device says that the course is under-distance, then it certainly is.

Moral of the story for the OP, best to ensure that events are accredited by Athletics Ireland (or BHAA). If it's not, then it's pot luck as to what the distance is. [Recent unregistered 5k near me came out on participants GPS as low as 2.85 miles]

- Condo(r)131 - AIMS/IAAF Grade B Measurer

Except if its the Grant Thornton 5k!! Always short and supported by Athletics ireland

Right2Write

Condo131 wrote: »

Many unregistered events measure using any random methods, from cars, trundle wheels, GPS, online mapping tools, etc. *NONE* of these methods is acceptable. The *ONLY* acceptable measurement method is using a Jones Counter.

Just curious - but why would a Jones counter be any more accurate than a trundle wheel? Both count revolutions of a wheel in contact with the ground. Arguably the latter is more appropriate since it's specifically designed for measurement.

Re GPS measurements, apart from factors like reception - the main 'problem' is how often they record a 'track point'. The unit records a series of track points like 'bread crumbs' and then calculates the straight line distance between each track point, adding all up from start to end of track. The start & end are defined by the runner in this case. Many GPS units have a default setting which just records a track point every so many seconds or after significant changes of direction. You can often set them to record at a predefined distance, so every 10 metres etc. The more track points, the closer the trace will follow the running route and the more accurate the overall measurement.

opus

Bluesquare wrote: »

Anybody know how parkruns are measured ? I did one recently that the garmin had slightly short at 4.94 ?

I used a trundle wheel (borrowed from Clonakilty parkrun) originally in Tramore Valley, see pic from back then. Don't know what was used in Ballincollig but it normally comes up at ~5.1k on my watch so it's there or thereabouts anyway.

Btw parkrun doesn't claim anywhere to have exact course measurement as far as I know so don't be claiming your 5k pb from one

TFBubendorfer

Right2Write wrote: »

Just curious - but why would a Jones counter be any more accurate than a trundle wheel? Both count revolutions of a wheel in contact with the ground. Arguably the latter is more appropriate since it's specifically designed for measurement.

When you walk with a trundle wheel you tend to "wobble" a bit, adding a little of extra distance.

Condo131

Right2Write wrote: »

Just curious - but why would a Jones counter be any more accurate than a trundle wheel? Both count revolutions of a wheel in contact with the ground. Arguably the latter is more appropriate since it's specifically designed for measurement.

Firstly, just to reiterate, Jones counter is the *ONLY* accepted method for AIMS, IAAF and Athletics Ireland events.

Trundle wheels are less accurate, for several reasons:
As Thomas said, users tend to wander - once came across two guys measuring a Sli na Slainte course, who were chatting away as they went along...a drunk could have walked a straighter line
Afaic, these wheels do not come with certification. Temperature will affect the diameter, no matter what material.
Wheels are not checked against a certified distance before use.
Pressure applied to the wheel is not uniform, hence ground contact cannot be guaranteed.

Jones counters are specifically designed for measurement.
Bike is calibrated BEFORE *AND* AFTER all measurements.
Calibration is made over a straight line course, usually 400m, but 300m min, which has been measured using a Certified steel rule - uncertified rules and non-steel are not acceptable - AND the calibration course is adjusted for temperature when being laid down first time. Steel rules are certified for 20C, so a few cm is normally added/subtracted when laying down.
Even pressure is maintained on the wheel, throughout.

A couple of years ago, a measurement colleague had a calibration course checked using a surveyor's wheel and they came up with a variation of approx. 6" over the 400m course. This translates to approx. 10m for a marathon. Close enough, some might say, however short is short.

...........AIMS/IAAF Measurer