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Sunday, May 9, 2010

Ed Llorca demonstrates CVC passing ettiquette on Stunt Road Descent.

The title of this is supposed to sound like the 1998 DVD Ballerini Shows Grace in Hell, a story of the late riders win at Paris-Roubaix.

I yell at the new guy in this one, as I knew he wanted to go left for water, and he had gone right first, making me incredibly nervous about what he was going to do next. I am learning that he can be trusted. I apologized for yelling at him at the bottom.

Anyway, this is another scenic desent in the Santa Monica Mountains, dropping 1300' in 4 miles. I can only imagine how fast Ed would go down this on a fast bent. ;-)


Ed Llorca demonstrates CVC passing ettiquette on Stunt Road Descent. from Jim Verheul on Vimeo.
GoPro HD on flashpoint bar mount, 1280x720p, 60fps, wide angle.

Cruisin' the Conejo Potrero Descent, passing technique.

Here is a short 5 minute descent that drops 1000 feet from Newbury Park , Ca, to the Oxnard plain. If you turn up the volume you can hear me apply the brakes hard a few times, and lightly during a few corners (trail braking).

I love the easy turns on top, its clear I can let it run for those. Then it tightens up a bit.

@ 0:37 you can see a rider has picked a really poor spot to stop, and I tell him so. He is just around a blind corner from the cyclists descending behind him, at the exact exit point of the turn, on a narrow shoulder that he cannot fit himself and his bike on, with his back to the place he might get hit from. Please think about other road users. There is a nice wide shoulder with much more visibility from both directions just a few feet down the hill. Fittingly, his jersey says he's armored. ;-)

@0:50 and 4:45 I pass too pairs of cyclists. I brake a bit on both occasion. I yell,"On your left" beforehand, and,"Thank you" as I pass. Both pairs are riding predictably and move a bit to the right or hold their line after I announce my presence. I try to always thank riders like that. Plus, I am pretty sure that even though they don't appear startled, my yell is only slightly less of a surprise than if I did not let them know.

Peak speed is over 50 where I pass the second pair of riders. Nice pavement!


CTC Potrero Descent from Jim Verheul on Vimeo.
This is from The Conejo Valley Cycling Clubs Cruising the Conejo flatland 68 mile ride. First you have to get to the flatland though, thus this 1000 foot drop from Dos Vientos to California State University at Channel Islands on the Oxnard Plain. Here is a map:



Cheers,
JV

Monday, May 3, 2010

Cda and Crr testing highracer vs highracer with a powermeter & Golden Cheetah AeroLab

I am usually too busy or ADD affected to actually go out and test, so I just dump the data I have into tools and see what I get. The crit I do on Thursday nights is not completely flat, but it is a loop. It was also very windy this Thursday. I spend the whole warm up ant the last 19 laps of the event riding pretty much alone, and then a 4 lap cool down.

This was on Carbent Raven (27 degree seat angle) with American Classic Hurricane wheels, used Continental GP 4000S tires (100#f/120#r), one with a butyl tube and one with Panaracer Greenlite tube. One bottle on a seat back cage, no seat bag. I was wearing Defeet wool Kneekers, a JBV Coaching LS jersey, and a Giro Atmos helmet.

This is getting me interested in going down to the same industrial park on a calm weekend and actually riding to collect data, not to train.

Anyway in the plot below you can see how well the tool (Roberts Chung's Aerolab in Golden Cheetah) works. The first level section is warming up alone, at a variety of speeds, but no coasting. The last level section is a 19 lap solo breakaway followed by 4 laps of cool down.

See the cool down laps slope up? My Cda goes from .268 to .286 there. Why? I was wearing a slightly heavier jacket, I had one more bottle, and I probably had one arm hanging or on my chest most of the time.


This is just a tease. The thing that really impressed me we how repeatable it is at a big variety of speeds and power levels. Maybe even bigger is that this was on the windiest day at the crit I have ever experienced! If it can look this steady lap to lap, I can't wait to see it on a calm day. The course has sections that are sheltered, some that are wide open and some where the wind can channel between buildings making it change direction.

At first I thought my Crr was different for the 2 level sections, but once I corrected for air density they were the same. Also, the course has 3 meters of elevation change per lap according to Ridewithgps.com. Aerolab shows an average of about 3 meters if you look at a bunch of laps. Good! In fact, I can look at the 1st 7 breakaway laps and see that my Cda was a bit lower, until I got smacked with a big gust of wind, probably from an angle. My Cda might have hit as low as .245 in the last 3 racing laps, due to a lull in the wind I guess.

I am working with Robert Chung to understand the data better, and how to interpret and apply it. An interesting question is what the drag of a reclined bent rider and bike does at different yaw angles. Are we more or less sensitive to that than our DF brethren?

Next I need to put the roof rack on my car so I can bring 2 bikes to the crit. Next up will be my 700c Bacchetta CarbonAero 2.0 with Hed Jet9s and a 22 degree seat angle, assuming is a bit calmer.

What I want to test later: bottle locations, wheels, clothes, and seat bags. 

References:
Weather at the time in Camarillo.

Although you can use Golden Cheetah to download data from my Powertap powermeter, I used TrainingPeaks WKO+ 3.0 and imported the file into Golden Cheetah. GC is only supposed to support WKO+ 2.2 files, but it seems to work. 

Adendum:
Here is the link that Robert refers to in his comment, from someone else who has dome some Chung method aero testing.: Colin's Biking Bits