Posted: 08/04/2014 at 14:21
Re course length compared to Garmin;
- Garmins are not absolutely accurate, I think even on on their website they state a percentage.
- The course is measured as the shortest route, 300mm from the kerb/fence so if there's a left turn followed by a right the measure goes diagonaly from one corner to the next. This is so that the lead runners (who are able to take the shortest route) can never run less that 26.2.
So if you're back down the field and always run on one side you're taking the long way round some corners and this adds up over the distance. I can run about 12 metres less on our parkrun than people who don't carefully take the diagonals. I measured the route so know the shortest way!
-The measurering machine (attached to a bike wheel) is calibrated to add a bit (0.01% maybe) so that if there are errors in measuring the total distance is wrong the right way (ie never short so that there isn't a world record set on a short course)
I would be very surprised if the 11m mile mark was at 11.5 miles, I was checking the race referee's timing against my watch (I was driving him) and they were running very close to 5 min miling, I tihnk we'd have noticed if they suddenly did a 7.5 and then a 2.5