Monday, February 1, 2016

Real World Bike Speed, Part II

Gordo Byrn: Real World Bike Speed, Part 2
By Gordo Byrn

In 2003/2004/2005, I had three podium finishes at Ironman events and managed one of the fastest times ever at Ironman Canada 2004 (8:29). However, those races were done with a 7 meter draft zone.

Bump the draft zone out to 10 meters and my position becomes more relevant. Why? Try sitting fourth wheel at 40 km.h with 5 meter gaps between bikes. You will very quickly see that 7 meters Ironman (front to front) is quasi-draft legal once you can hold 40 km.h. To race well in the agegroup ranks you must learn how to use your competition both effectively and ethically.

Recognizing this fact, I have been working on getting more slippery. With four months until my 40th birthday, there is limited upside with my horsepower. My current position is photographed below.

Things that I want you to notice:

Wheels -- 1080 front, sub-9 disc rear -- this is an insanely fast wheel combo. If you are going to run the 1080 then you must practice in training. If I had to choose my single greatest source of speed then the wheel set wins. I used to be highly skeptical about the impact of wheels until I put these on my bike.

Vision -- I can see up the road without straining my neck. I can't see far... but I can see far enough.

Helmet -- Giro Advantage Two -- if you are a heavy sweater, racing in hot weather, or suffer from dehydration on the run... then GO VENTS. If you are racing in the cold then an aerohelmet is the most efficient way to keep your core temperature up. Keep the tail down against your back (my IMNZ race photo shows a big gap, that is a no-no).

Seat Height -- at the high end of acceptable, seems to work for me.

Cleanliness -- no bottles catching the air coming down my back. My spares are in a bike bottle in my seat tube bottle cage. Fluids are via aerobar mount and down tube bottles -- can be accessed with minimal body movement. I wear a skinsuit, so there is no flapping clothing.

Arm position -- Going narrow as sped me up (see differences in photos below). The ONLY way that I can hold a narrow position is to pull my elbows backwards towards my hips. I run a very shot stem.



One more photo so you can see nose of saddle relative to BB (below). When TTing at high power (>FTP), I slide forward to the nose of the saddle. This saddle position is a compromise, I have found that I lose too much climbing power/comfort if the saddle goes any more forward. With the PX frame geometry, I am at the limit of how far forward I can go.

While it might be tempting to slam even more forward... remember that you need a place to put your head and you don't want to create chronic neck pain. Your TT position needs to be comfortable, otherwise you'll never train in it!

A couple of final points to consider:

Wind Tunnels -- I spent several thousand dollars with wind tunnel testing a few years ago. Frankly, it gave me the wrong answer. I recommend field testing, ideally race performance data.

Ride Strategy -- How you use your position is as important as the position itself. I am looking for a position that enables me to relax in the fast parts of the course and be comfortably powerful in the slow parts of the course.

I have power variability in my rides because I rest at high speed. I avoid power spikes as they impair my run for very little time gain. I will, however, lift my power in the slow part of the course. I am constantly considering effort versus air speed when TTing.

The bike is the only part of a triathlon where you can coast with very little time penalty. The run provides ample opportunity to lay it down, as well as, the greatest time penalty for cracking.


What to Optimize?
Triathlon cycling has little to do with elite road TTing or the 4K pursuit. While we can learn from elite cyclists, we need to remember that our event has different physiological requirements.

Here is my ride logic:

#1 -- what is my best case scenario for power output and average speed across the race distance, ignoring the run?

#2 -- what is the fastest position that I can hold at 95% of best case power?

#3 -- open with (at least) the first fifth of the ride at 90% of best case power. Lower heart rate into my target zone and establish hydration, nutrition and comfort.

#4 -- if I am feeling good then gradually shift upwards to 95% of best case power and hold as RPE increases across the ride duration.

#5 -- invest my greatest effort into the slowest parts of the course. Remember that (nearly) every meter of the run will be slower than the bike.

#6 -- until I run well, keep lowering my target bike effort.


What is it Worth?
The changes that I outline above have removed 30 watts (~11%) from the power required for me to average 40 km.h here in Boulder. I suspect the key three changes are: improved wheels; smaller wind scoop; and smarter application of power. I have field tested with aerobic TTs from 20 minutes to 2 hours.

The two things left for me to consider are my fork/front wheel combo as well as my wrist height (guys like Levi seem to lift arm angle to close off the wind scoop entrance, Fabian less so).

With a bit of luck, I may be able to pull a couple more watts out.