Official race distance vs actual distance run

Hi. Couldn't think where else to put this so here it is!

Ran my very first race yesterday - the Bristol 10km. I'd really hoped to do it in an hour but actually recorded 1.10.37. However, I also used the fitness app on my ipod to measure my pace etc on the way around - and it recorded I'd actually run 11.67km! I swear I didn't hit 'start' until I was over the line and remembered to stop it once I'd crossed the finish line so, even allowing for some inaccuracies, it still seems I ran further than the 'official' distance. Of course, that means everyone else must have done too to some extent :-D I'm guessing this was due to weaving in and out overtaking and - through my own lack of experience - not necessarily picking the optimum route.

So, I guess I did do 10km in an hour - and the rest was a bonus ;-D but it's also a bit disheartening - good job I didn't check how far I'd gone earlier or I might have just said to hell with it and given up before the finish line ;-D

Anway, I'm curious - is this a common problem? Will the distance I measure get closer to the official distance once I've got a few more races under my belt? And how do I get better at planning the optimum route round?

PO Poppy Field

0 12 Categories events 21 May 12

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  1. Boothy

    Boothy At the end of a 4 mile race at Arncliffe last Saturday my Garmin 205 Forerunner read 4.06 miles. I read morementioned this to the race organiser who told me the course was actually 100m over 4 miles, so my Garmin was spot on.

    0 15 Aug 12
  2. TI

    tim13 Garmin Forerunner is pretty good - maps closely to km and mile markers in races and also to "route read moremapping" software on the internet. +- 50m in 10K

    0 15 Aug 12
  3. IB

    ibelieveican my nano is never acurate..but what a great feeling when you think youve run 2.5miles and when you read morecheck using car mileage its actually 3miles....smugness...and the sweaty tops justified...

    0 6 Jun 12
  4. MH

    mh1 Started out using nike+ now I have a forerunner 110 which is much more accurate and which I find read moremuch more useful for mapping routes etc

    0 28 May 12
  5. mcboro101

    mcboro101 I have a Garmin Forerunner its pretty much bang on all the time, the most it is out is .05 of a mile read moreover 10k. When i run with my friend who uses his iphone its usually nowhere near the right distance. hope that helps

    0 23 May 12
  6. Purple Peril

    Purple Peril Have you tried mapping it on Map My Run? I use it for planning routes and find it very accurate. read moreFree to sign up and use if you don't mind a few adverts.

    0 23 May 12
  7. PO

    Poppy Field Curses! And all this time I thought I was already running 10km :-( Still, on the upside at least I read moreactually *have* now! Am hopefully going to start going to our local park run so I can build up better speed and time over 5k. For a laff will also 'measure' it using my Nike+ and see what it tells me I'm doing!

    0 22 May 12
  8. Chubby Bloke

    Chubby Bloke Nike+ is inaccurate. Don't trust it. Get a forerunner!

    0 22 May 12
  9. bretrunner

    bretrunner If your device you use is claiming 90% accuracy then over a 10k course it can be 10% out so thats read moreplus or minus 1k, with the weave you will experience in a race its not beyond the realms that your device read 11.67km.

    The downside for you however is that you have not run the distance you stated due to the error in your equipment.

    All UKA races have to have a certificate of accuracy issued before they get a race licence, so that anyone racing has the confidence that the distance covered is the distance stated, they are accurate to within 0.1% which is plus or minus 10metres.

    GPS devices and other similar devices should be used as a guide only, they will screw with your mind. I never race with one just a std stop watch.

    0 22 May 12
  10. CM

    cmmercer I don't know how that works, but if it works on stride rate or something similar then surely going read moreup a hill would affect distance as your stride shortens and cadence increases.

    0 22 May 12
  11. PO

    Poppy Field Hmmm. Interesting. I'm using an ipod nano with Nike+ fitness on it, not an iphone (no idea if this read moremakes a difference!) which claims to be accurate to around 90%. I think I'll take it with me next time I'm on the treadmill and see if what it measures equates to what the treadmill is telling me to get a better idea of how accurate/inaccurate it is.

    0 21 May 12
  12. CM

    cmmercer The distance calculation on a phone is not to be trusted at all. There will be a degree of extra read moredistance covered by some weaving, but generally GPS refresh rates on a phone will not allow for an accurate measurement and should not be trusted. Even specific GPS devices will rarely be accurate as there is always an element of delay and any issues in high rise built up areas or similar. To be certified the course will have been accurately measured and the only way to hit this distance perfectly is to know the exact route it travelled (the blue painted line at London Marathon).

    0 21 May 12