The 2012 edition of the Rotorua Half utilised an altered cycle leg compared to previous years thanks to a land slip on the road to Whakatane. As we all know, change is evil as it hampers comparisons. Luckily – one of the core values in the Speed Theory mission statement is:
If it can be analysed it can be over-analysed
So I’ve built models of both the original and revised courses in order to compare their difficulty and the impact on times.
The simplest factor to look at – my records show the 2012 Rotorua Half course to be 500m shorter than the original route. Which will make a difference of 50-70s to the overall time.
Time for a picture:
My data shows the total amount of climbing for the 2012 Rotorua Half course to be 999m compared to 763m for the original route. How much time that adds depends on your mass and power profile (and motivation – I had misplaced my mojo by the time I came back up Tarawera – not the first time that has happened). That effect will be captured in the modelling.
Equally bad – this is Waikato-Bay of Plenty afterall.
My data source for the 2012 Rotorua Half course has very fine detail – over 9000 segments of direction and gradient. Compared to 650 segments in the data for the original course. It doesn’t mean much for the output – just that it takes longer to set up the model (which is part of why it has taken over a month for this to be finished).
It’s useful that I rode the course myself so have power data to validate the new model – entering the weather data from the day and my stats (power, weight, aero drag) gets very good agreement with the time I actually rode (which was not flash as I’d been sick all week).
Obviously you’re a sucker for punishment if you did the Rotorua Half – if that masochism extends to being interested in how I do this analysis – click on the thumbnail to the right to see the data that gets input into the model to generate these comparisons.
I’m not going to explain all those values – but as you may guess from the stored energy and training stress calculations – when I give my athletes pacing instructions I’ve really put some effort into it.
The model predicts that I should have hit 86.6kph down Tarawera, but I had to brake a little for another rider so only maxed at 83.9kph. Pretty good indication of how well the formulae work though.
And at the end of all the analysis I come out knowing that I would have been 3.50min faster on the old course, despite the longer distance.
For a 70kg rider going around the 2.30hr region the difference would only be 2.15min – reflecting the impact that the extra climbing has for those of us in the Clydesdale category.
This chart summarises the time advantage of the old course depending on your size and speed. For instance – a 75kg athlete taking 3.30hr on the 2012 bike course would be 8.00mins faster on the old course in the same conditions.
Additionally – the average bike splits were 5min slower than the previous year – which supports the results of the modelling (it’s always nice to have verification).
The new course is hillier and slower. Which obviously makes it better as you don’t turn up for the Rotorua Half wanting a gentle walk in the park do you?
Sorry I hadn’t completed this analysis prior to the Survey. So does anyone want to change their answer for the preferred route for 2013 now??