Race Time Prediction

This analysis had not been updated for nearly three years, so it was long overdue for an update. The list of events covered by the race time prediction analysis has now grown to include 49 events and/or distances. While the analysis was initially intended to focus on ultramarathons, it has expanded to include a wider range of trail and mountain running events, including multiple at sub-marathon distance. All recent variants of the Tarawera Ultramarathon. Five ultramarathons no longer held (or superseded by course changes) have been included for historical interest.

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The full list of events is:

• Sub-marathon trail run:
  • Avalanche Peak Challenge (old distance);
  • The Hillary 34km;
  • Jumbo-Holdsworth Trail Race;
  • The Kaweka 36km;
  • Routeburn Classic;
  • Tararua Mountain Race (Southern Crossing);
  • Tararua Mountain Race (Kaitoke-Holdsworth).
• Marathons:
  • DUAL Trail Marathon;
  • Motutapu Marathon;
  • New Plymouth Marathon (which is net downhill and fast);
  • Standard Marathon;
  • T42 Trail Marathon;
  • XTERRA Waihi Marathon.
• Ultramarathons:
  • Reference^* 50km, 80km, 100km;
  • Bedrock Ultramarathon;
  • Great Naseby Water Race 50km, 80km, 100km, 100 mile;
  • Hutt River Trail Ultramarathon 60km;
  • "Kaimai Killer" 60km;
  • The Kaweka 50km;
  • Kepler Challenge 60km;
  • Length of the Lake 67.5km;
  • Marton-Wanganui 67km;
  • Molesworth Run;
  • Northburn 100 mile;
  • Taranaki "Round the Mountain" 100 mile;
  • Tarawera normal course 60km, 85km, 100km;
  • Tarawera fire course 60km, 85km, 100km;
  • Tarawera cyclone course 60km, 72km;
  • Te Houtaewa Challenge 90 Mile Beach;
  • Triple Peaks 47km.
• Ultramarathons no longer held:
  • Heaphy Five-O;
  • St James Ultra;
  • Tarawera 2009;
  • Taupo 100km pre-2009 (very hilly first 45km);
  • Taupo 100km 2 Lap (2009);
  • Taupo 100km 4 Lap (2010, 2011);

* Note: The Sri Chinmoy 50km and 100km events (Christchurch) are counted as "reference" 50km and 100km events due to the flat, fast nature of the course.

The updated table of multipliers is given below.

The methodology remains as described in my May 2010 post. One commenter on the 2011 analysis observed that the change in the rate of slow down from 1.197 (2010) to 1.120 (2011) was a significant change and that perhaps more data was required. We now have more data, a lot more data... 9,514 paired observations. The rate of slow down is derived from the latest analysis is 1.208, consistent with the 2010 estimate.

Table 1: Race Time Prediction Multipliers, Ordered by Multiplier

Event	Distance (km)	Multiplier
New Plymouth Marathon	42.2	0.969
Standard Marathon	42.2	1.000
Jumbo-Holdsworth	24	1.038
Avalanche Peak	26	1.059
Motutapu Marathon	42.2	1.196
T42 Trail Marathon	42.2	1.199
Routeburn Classic	38	1.226
Reference 50k	50	1.227
Dual Trail Marathon	42.2	1.309
Hillary 34km	34	1.347
Naseby 50k	50	1.422
Triple Peaks	47	1.598
Hutt River Trail	60.25	1.617
Waihi Marathon	42.2	1.656
TMR: Kaitoke-Holdsworth	40	1.792
90 Mile Beach	60	1.819
Marton-Wanganui	67	1.820
Length of the Lake	67.5	1.886
Bedrock Ultramarathon	52	1.925
Kaweka 36km	36	1.962
Tararua Mountain Race	35	1.990
Kepler Challenge	61.3	2.155
Reference 80k	80	2.165
Tarawera Fire 60km	60	2.184
Tarawera 60km	60	2.259
Tarawera "Cyclone" 60km	60	2.308
Northburn 50km	50	2.353
Naseby 80k	80	2.509
Tarawera "Cyclone" 72km	72	2.615
Molesworth Run	84	2.620
Kaweka 50km	50	2.649
Kaimai Killer	60	2.673
St James Ultra	67.2	2.689
Heaphy Five-O	78.4	2.767
Reference 100k	100	2.835
Taupo 4 Lap (2010)	100	2.908
Tarawera 2009	89	3.098
Taupo 2 Lap (2009)	100	3.156
Taupo pre-2009	100	3.175
Tarawera 87.5km	87.5	3.184
Naseby 100k	100	3.285
Hillary Ultra	80	3.349
Tarawera Fire 85km	85	3.403
Tarawera 100km	100	3.654
Tarawera Fire 100km	100	4.034
Northburn 100km	100	5.605
Taranaki Round the Mountain	160	5.781
Naseby 100 mile	160	5.796
Northburn 100 mile	160	11.055

Charts

The table and slow down factor enables us to produce some comparisons of races of the same or similar distance. Charts are provided below for 50km, 60km, 100km, and 100 mile races. The blue bar is the marathon time multiplier that is due to the distance of the event. The red-brown bar is the additional multiplier due to the "difficulty" of the event, whether that is due to climb, technical surface, altitude, etc. Over the longer distances (100km, 100 mile) Northburn is clearly the most difficult event, but over the shorter distance of 50km the Kaweka is more difficult.