Thursday, October 25, 2012

ChesapeakeMan 2012 Power File Analysis

ChesapeakeMan Power File

Above is my power file from the ChesapeakeMan Ultra Distance triathlon 2012. For background, I raced on my custom Guru CR9.01 (from Parvilla Cycle & Multisport) with Rotor Quarq crank based power meter, Mavic Cosmic Carbone 80 front and Mavic Comete Disc and Spiuk Chrono aero helmet.

With an Functional Threshold Power of 295 watts and a racing weight of 165lbs  (3.94w/kg), my goal power for the race, taken from training sessions and calculations was between 195 - 205watts.  From experience and training leading up to the race I knew that this would be what I needed in order to run well after the 112 miles.  Overall the bike split time was 5hr 14mins at 21.4mph.

Through the first half of the bike (0-56miles) the data was:
Normalized Power: 208
Average Power: 204
Average HR: 131
Training Stress Score (TSS): 120
Kilojoules Burned (KJ): 1845
Intensity Factor (IF): 0.69
Variation Index (VI): 1.02

This was pretty much spot on and importantly the variation index was low at just 2%, which meant that the ride had been a consistent power level with very minimal changes.  The IF was about right and the HR had remained at the same intensity.

The wind kicked up a bit for the second half of the bike (56-112miles) and the data was:
Normalized Power: 192
Average Power: 188
Average HR: 126
Training Stress Score (TSS): 111
Kilojoules Burned (KJ): 1853
Intensity Factor (IF): 0.64
Variation Index (VI): 1.02

As you can see the power (NP and Ave) went down by about 8% over the 2nd half, which is often the case over the Ironman distance but the HR remained similar.  Importantly the VI stayed at 2% so the bike throughout was very consistent from a power perspective.  The wind definitely played a factor in the power reduction but it was also expected and part of the race day strategy to ensure a good run. 

Ultimately the good run did happen for a 3hr 17min marathon and a 10min Ironman marathon PR.

So now the goal for 2013 is increase that power level leading to a faster bike split but still keep the run speed!  It's a tricky process.......


Anonymous said...

So you can ride on about anything, why the Mavics? I love my Mavic Ksyrium Elite wheels but punted on their aero wheels since they seems more for road racing than TT/Tri. Granted, the 80 was still a rumor that it would go beyond tour riders. You also stated that your goal power output was 195 – 205 watts. Is that the top of your zone 2? It seems that you were able to nail it pretty well on that course even with some wind. How did this compare to St. George IM? Were you able to keep that in a consistent (and tight( power range too?

Iain Banks said...

Weight is one advantage, the Mavic's and the disc especially are amongst the lightest you can get. They def. should be on your radar for TT/Tri...the new Cosmic CXR80 is the fastest wheelset on the market (and legal for tri). I might look at the HED tri spoke for 2013.

195-205 is close to my top end of Zone 2. Technically it is about 215watts but from training I knew that the 195-205 range would work better. For IM you can't just suddenly go out and ride at a power your haven't been riding in training. ChesapeakeMan is an easy course to get the power dialed in but most courses you can do that if you are patient and don't get caught up in the race. Hillier courses will probably give you a higher VI but keeping it between 5-8% is realistic on a coure like Lake Placid. When I did IMLP in 2010 I didn't have power at the time but HR VI was in that range.

IM St George was a tough, tough day and it was real hard to pace with power on that course with the winds and hills, very much an anomaly. My average power was 194watts, NP was 222watts and that gives me a VI of 1.14. At points I was pushing over 300watts going downhill into the wind....and that was halfway through the 30mile climb every lap! It certainly contributed to a slow day on the run.