How far did you run in your last race? The truth is there is no exact answer to the question. While the pre race blurb may have stated that it was 10K or a marathon, what you ran is another matter. With more and more race directors taking up the option of having courses measured by the only recognised international system it is perhaps important that runners have some insight into the dark arts of the Jones Counter.
First of all let us consider what the alternatives are. In the past, Ordinance Survey maps and pieces of string were the norm a practice which today can be replaced by using the ruler tool in Google Earth. For some the most comfortable method was to get in the car and drive round the course, not always possible when pedestrian walkways are involved. Then there is the good old Surveyor’s Wheel which is walked or run round the course – time consuming and tiring if you are doing a marathon. And of course there is the wonder of scientific magic called the Global Positioning System ( GPS ) which somehow makes contact with satellites which track your every move.
All of the above ‘can’ produce fairly accurate results but they can also result in some very dodgy calculations which lead to either depression or ecstasy depending on whether the ‘error’ is long or short. Generally it is short! I well remember running a personal best 1000 metres during a local 10k not too many years ago, better than I was ever able to do on the track decades ago when I was a useful 800m runner. Race directors of course do not (we hope) intentionally make races short (or long for that matter). Most of them are runners themselves and they have used the best method available to them.
The problems with the above methods are various. Maps are not detailed enough, wheels bounce and keep turning, GPS can (and does) lose contact with satellites and as for the car there is little chance of it following the racing line. So how do you ensure, if not absolute accuracy then, at the very least, consistencey.
Enter the Jones Counter. Throughout the World it is accepted that the only accurate way to measure a course is using this little device attached to the hub of a bicycle wheel. Indeed in many areas (eg. the Republic of Ireland ) permits will only be issued for courses measured in this way. A failure to re-measure the Dublin Marathon course last year after minor changes resulted in a Beijing Qualifying run being ruled unacceptable.
The Jones Counter does not guarantee precise accuracy. As stated before this is impossible. What it does guarantee is that no runner in the race, following the set course and within the criteria laid down by the organisers (eg. No running on footpath, no cutting across roundabouts etc), will run less than the declared distance of the course.
How then does it work? While similar in appearance to the old device which measured distance the Jones Counter only provides the measurer with a number of registered clicks. Thus the starting figure might be 600000 and the finishing reading 654321. The difference between them is therefore 54321 clicks. This of course is meaningless unless you know what each click represents and that will be different every time you ride the bike. This is where the pre-measurement calibration comes in.
Every measurer will have his own carefully measured calibration course. In my case this is a 400 metres straight measured using a 50m steel tape with a set of hand scales to get the correct tension and a thermometer which measures ground temperature with an appropriate correction being made based on manufactures guidelines. This course is defined by nails driven into the road at either end.
On the morning of any course measurement this precise 400m is ridden four times with the number of clicks registered each time. These are then averaged to give a number of clicks per 400m. Depending on whether the course director is looking for kilometre or mile markers the following calculations are made:
Clicks per kilometre = Average No. of clicks per 400m X 2.5 x 1.001
Clicks per mile = Average No. of clicks per 400m x 2.5 x 1.60934 x 1.001
What is the 1.001 calculation all about you might ask? The answer is that it is a built in safety device to ensure that the course is never too short. Thus a 1m per 1000m addition is built in to all calculations. Thus a 10000 metres could be up to 10 metres long and a marathon up to 42 metres long.
Having done all his calculations the course measurer heads off to do the business. He cycles the course presented by the race director setting down kilometre or mile markers as required and informs the director of any adjustments that are required. Since most measurements are done backwards because finish lines are usually sacrosanct the adjustments are generally made to the start but in some cases where start and finish are both set in stone (eg the Belfast Marathon) it is sometimes necessary to make adjustments around the course (not always easy!).
This is not the end of the measurer’s day. He must now return to his calibration course and do another four rides and redo the calculations to make sure that tyre deflation has not had a significant effect on his measurements. It is recommended that the higher of the two readings is used and this can mean minor changes being made (for example in a recent marathon measurement 3 metres had to be added).
None of this means that you are any closer to knowing ‘exactly’ how far you have run in your last race or how far you will run in your next. Remember all runners in any race, which is not run in a straight line, will run slightly different distances. What it does mean is that you can be sure that any race which uses the Jones Counter for the course measurement will mean that you will have run at least the declared distance and that these distances be they in Northern Ireland, the Republic of Ireland or anywhere else in the World will be consistent.
Recent courses in Northern Ireland which have been measured by a Jones Wheel include:
Belfast Marathon Newry Marathon and Half Marathon Omagh Half Marathon
Joe Seeley 10k Titanic 10k Veterans 5 Mile
Banbridge 10k Run Armagh 10k (next April 19 th ) Bangor classic 10K
Ards Half Marathon Les Jones 10k
Larne Half marathon and Draperstown 10k soon to be measured
