How we calculate your seeding
There are 5 steps involved in the seeding process:
1. Choosing the weightings of the different rides
2. Establishing a base event
3. For each ride, adjusting the winner’s time and calculating its difficulty relative to the base event
4. Calculating an index for each rider
5. Calculating a weighted average for each cyclist
6. If your weighted average index is better than your current seeding, then you are eligible to move to a better group.
In more detail:
1. Choosing the weighting of the different rides
Rides count for different percentages of your total seeding, depending on the difficulty, distance and the status of the event. The 2011 Cape Argus Pick n
Pay Cycle Tour will count 50% (half your total seeding, provided it was one of your best three results) and the other funride routes will count different percentages, based on the weighting of the event.
The weighting of an event is based on the number of finishers in the event, as well as other factors (see (c) below). Most long routes are weighted 34% (so 3 long routes will make a full seeding). In some instances some events/routes do not meet all the criteria needed for seeding, and will therefore not be used, or the event will not carry the full route weighting.
Only your best results are used for seeding purposes – the rest are discarded from the calculation. (So it never hurts to have a bad result because a bad result is better than no result at all!). You need enough results to make up 100% before the seeding system starts working properly for you.
What are the criteria for an event to be used for your seeding?
(a) The event must be timed by RaceTec or the results imported by RaceTec onto their system.
(b) For each route, there must be at least 50 finishers who have also done the base event as well as the event in question, and who also have an index under 100 (roughly double the winner’s time on average).
(c) There must be no problems that prevent the calculation of the event’s difficulty relative to the Cycle Tour. On the event management side, this could happen if too many riders follow incorrect routes. It also often happens for shorter routes of events where the majority of participants are riding “just for fun” and their index for the event in question and the most recent Cycle Tour do not match up.
2. Establishing a base event
Step 3 below relies on us being able to compare the difficulty of different events. And for that we need a base event. Ideally we would just use the latest Cycle Tour (Cape Argus Pick n Pay Cycle Tour 2011) but to enable us to do the calculation equally well for all events across the country, we first perform steps 3 and 4 below for the 2010 Momentum 94.7 Cycle Challenge and then use the better of the two indices as our theoretical base event. The result is that both these events are treated as being slightly easier than the theoretical base that we use in practice.
3. For each ride, adjust the winner’s time and calculate the difficulty (beta)
Some races have a better quality of field than others. For instance, some events may have visiting pro riders participate and some events (especially shorter routes) have no top riders present. So we adjust the winner’s time to take this into account.
It would also be unfair to get the same seeding for being the same percentage behind the winner in a fast, flat ride as in a hilly, difficult ride. To allow for this we calculate a difficulty or “beta” factor. This makes the gap between the winner and you count less in difficult conditions and more in easy conditions.
First, an extract is done of all the riders who did the event in question, as well as the base event. Every rider with an index better than 100 is taken for this calculation. The assumption is made that the same riders should have the same index for both events, so the winner’s time of the funride is now adjusted and the “beta” is calculated to achieve this.
In statistical terms, a linear regression is performed for the event relative to the indexes of the people in the event who also rode one of the base events. This determines how much the winner’s time should be adjusted and what the difficulty factor “beta” should be. There is no subjectivity in this process – it is an automated calculation without human intervention.
In layman’s terms, the adjusted winner’s time should be roughly the time that the winner of an event would have done if the winner of the Cycle Tour had ridden that event at the same effort. The beta factor will be 1 if the event is as difficult as (i.e. on par with) the Cycle Tour, less than 1 if it is easier (eg flat and fast), and more than 1 if it is harder (eg hilly or very windy).
4. Calculating an index for each rider for each of the different seeding rides
This calculation is done for every result in an event that counts for seeding.
The formula is: (your time / adjusted winner’s time – 1) / beta value and then expressed as a percentage. 1% is added to this for every complete month more than 3 that have elapsed from the day of the event to the date at which the most recent seeding run took place. The initial seeding run is done as at the same date as the first re-run which is 1 October 2011.
So if the adjusted winner’s time is 3:20 and your time is 4:00, and the event took place 9 months ago then your index for the event is (240/200 – 1) = 0.2 = 20%. Plus 6% for the time elapsed gives 26%.
5. Calculating a weighted average of the different rides for each cyclist
Your indices for all the events you have ridden are sorted from best to worst. All results below 4th place in your list (assuming the weightings of your best 3 add up to at least 100) are then discarded, and your overall index is just an average of the indexes from your top 3 rides.
A worked example:
Let’s say you have ridden 4 events where the abovementioned criteria are met and the results are all recent [less than 6 months old] so no penalties have been added
(a) Event A (counts 34%) – time 3:26
(b) Event B (counts 34%) – time 3:13
(c) Event C (counts 34%) – time 2:57
(d) Event D (counts 34%) – time 3:15
The respective adjusted winner’s times are 2:32, 2:34, 2:14 and 2:30 with difficulty factors 0.8, 0,95, 1 and 1.3 respectively.
So your index for the rides would be:
(a) (206/152-1)/0.8×100 = 44.41 (counts 34%)
(b) (193/154-1)/0.95×100 = 26.66 (counts 34%)
(c) (177/134-1)/1×100 = 32.09 (counts 34%)
(d) (195/150-1)/1.3×100) = 23.08 (counts 34%)
You would then sort these in order of index (best to worst) which would be (d), (b), (c), (a).
So race (d) will count 34%, race (b) will count 34%. At this point we only need another 32% to get to 100% so race (c) will count 32%, and race (a) will not be used at all.
Your overall index is therefore 0.34 x 23.08 + 0.34 x 26.66 +0.32 x 32.09 = 27.82%.
6. Get your new number…
If your seeding has improved, please contact the PPA Office to arrange upgrading your seeded number. An admin fee of R50 is payable, and you need to return your old (current) number before you can be issued with a new number.
In the table below, you’ll see your results have been sorted to show your best rides first, in other words the rides that count towards determining your seeding. All other results are then show in date order, with the most recent event at the top of the list.
