Wednesday, 10 April 2013

Early Season Hilly Time Trials - How Hard Are They ?

Just for fun, I thought I would compare and contrast some of the early season hilly time trials I have been entering. These are all mainly in the Cheshire or North Wales border region.

The ones I have entered in 2013 are:
  • Chester Hilly 14 (23rd Feb 2013 - snow !)
  • Oswestry Paragons Hilly 17 (16th March 2013 -wet)
  • Birkenhead North End Cycling Club Hilly 22 (Good Friday 2013 - very very cold)
  • Wrexham Mountain Time Trial - 24 miles (takes place on 14th April 2013)
I also did these in 2012 (apart from the BNECC one).

I've graphed below the profile of each of these time trials - I've normalised the altitude so the start point of the time trial is always at zero.


Clearly, the Chester Hilly TT looks fairly flat compared to the others, whereas the Oswestry Hilly 17 and the Wrexham Hilly 24 look pretty challenging.

If I take the "reported" elevation gains (from a Garmin 800), I find the following results:
  • Chester Hilly 17, elevation gain approx 180 feet: Height gain (feet) per mile = 12.4
  • BNECC Hilly 22, elevation gain approx 480 feet: Height gain (feet) per mile = 22.8
  • Oswestry Hilly 17, elevation gain approx 920 feet: Height gain (feet) per mile = 54.2
  • Wrexham Hilly 24, elevation gain approx 1950 feet: Height gain (feet) per mile = 81.2
If I plot my speed in these events, and the median speed, and the maximum speed, there is an approximate straight line fit (decreasing with increasing height gain per mile).

I assume the different lines are simply due to the different power/weight ratio of the riders. If you assume the power/weight ratio of competitors is distributed normally (i.e. like a Gaussian distribution) you would expect roughly a normal distribution of times in one of these time trials and this seems to be roughly true (see below 2012 results from the Oswestry Hilly 17).

Anyhow the reason for doing all this is I wanted to know what sort of speed I should expect for hilly time trials - by looking at the height gain (feet) per mile, I can get a pretty good idea of what speed I should be aiming for, and whether the ride is a good, average or poor one.