CdA under 0.20. Yes, astonishingly exceptional.
That seems even low for me and I’m a lot smaller.
jaretj
Those with the ability to record this data, can any of you get close to 50kph puting out only 345 watts?
Do you realize that with powercranks, you could crank your power up to 483 watts (average user) and easily reach your goal ?
Francois (sorry I could not resist) in Montreal.
Given that I’m 6’4" and 82kg, I’m guessing this weight is Maggie’s data from his impromptu CycleOps session on the hotel roof. I believe the data other than the speed.
sea level, negligible yaw, track surface, round and round (not perfectly flat), but certainly no hills.
Total mass?
Assumptions: Board track with good tires/glue giving Crr in the 0.0025-0.0030 range An extra 8kg for bike and kit (total 87kg) Temp 20C No wind
I estimate CdA around 0.190-0.200 m^2.
Don’t forget that you need to correct for the apparent decrease in CdA (and increase in Crr) that results from banking through the turns. It’s a small effect, to be sure, but it isn’t entirely insignificant.
Anyway, back to the original question: unless the data were collected when the track was almost completely empty, it’s possible that the power requirement is artificially low simply due to riders stirring the air around. For example, at ADT I’ve measured wind speeds at trackside as high as 2 m/s (albeit when the track was quite crowded).
I weigh 83 kg, and I am certainly not a body made for aerodynamics; I’m pretty broad shouldered and bulky (I’m 5’9"). It appears that I’m not too far off that mark, though. This screenshot is from Saturday, TT bike, regular clothes (shorts, jersey, gloves, arm warmers, no aero helmet). It was very close to windless. The highlight was with me in front of our Saturday ride group, trying to tire them out before the sprint point.
Note that the speed was declining during the effort you have marked…
tough to believe. for my own sake, i hope this isn’t an actual human we are talking about. a baby dolphin, sure, but a 79kg man with a uci legal position and a cda under .2? that’s disturbing.
I don’t have the tools to correct for those effects.
Sure you do:
http://www.sportsci.org/2006/CdA_calculator.xls
You’d need the exact turn radii and the like?
That, and the height of the center of mass.
The two effects would tend to offset one another wouldn’t they?
I’m not sure exactly what you mean?
Anyhow, I’d be interested in seeing the effect once you’ve done the calcs 
Are you trying to Huck Finn me into doing your work for you? 
Of course we’re all assuming the power-meter is working properly and has been zeroed etc.
…and that the file hasn’t been…er…“physicianed”
.
Anyhow, I’d be interested in seeing the effect once you’ve done the calcs
Are you trying to Huck Finn me into doing your work for you?
It was TOM SAWYER dammit!!!
Hello,
You might also want to post on biketechreview.com, they have a lot of techies over there.
Styrrell
I am not sure you want to trust biketechreview.com. On the front page of their website, their moving average line for kdublog is leading the actual data. Where is Wall Street, they discovered a leading indicator with a moving average line!
Anyhow, I’d be interested in seeing the effect once you’ve done the calcs
Are you trying to Huck Finn me into doing your work for you?
It was TOM SAWYER dammit!!!
http://www.pbs.org/...re/writings_tom.html
Hook, line, and sinker…
Anyhow, I’d be interested in seeing the effect once you’ve done the calcs
Are you trying to Huck Finn me into doing your work for you?
It was TOM SAWYER dammit!!!
http://www.pbs.org/...re/writings_tom.html
Hook, line, and sinker…
Just doing my part (again) to make sure y’all are properly educated on American literary classics.
… it does seem mighty unfair to deprive you of the pleasure of actually working out those intricate details …
Tracks just make ma’ head spin …
Well, we still need clarification from SuperDave re. the total mass, etc. But, to illustrate the issue: if I treat the data that we collected on ADT back in June as if it were obtained on a flat, straight road instead of a banked track, CdA is overestimated by 0.004 m^2, while mu (the global coefficient of friction) is underestimated by 0.001. So, not a huge difference, but not completely insignificant, either.
(BTW, while I was at it I looked up how much power my <<79 kg wife would have to produce to maintain 50 kph on ADT…assuming an air density of 1.184 g/L, the answer is 359 W.)
Ok, lets just change the numbers to 80kg TOTAL mass, 50kph, and 350 watts. I like those round numbers much better and they are more vague for those speculative lurkers.
AC I’m sure you know the list of riders that are under 43:XX for a 40km.
I was about to say ‘absolutely impossible’, then I realized that Friedman is about my height, but is probably close to 79kg–and I suspect he could be in that range.
Otherwise, my bet is on total mass–and Pate and the two new pro tour guys may be close to that.
Ok, lets just change the numbers to 80kg TOTAL mass, 50kph, and 350 watts.
Well in that case, there are a lot of riders who can achieve this benchmark even at sea level…including (if the air density is a tad lower than usual) yours truly.