What do you do to not be a Human Parachute?
I came across this cool blog on slowtwitch:
http://forum.slowtwitch.com/gforum.cgi?post=3499977
They collected data on average watts vs. MPH in their latest races, then plotted it out. I was shocked to find out how many riders post bike speeds of 23+ mph on about 3.2-3.4 W/kg. Same shock to see gobs of riders at 23-25 mph with average watts under 240. I have yet to convincingly break 22mph in a sprint or oly tri, and I tested FTP recently at 242W and 3.25 W/kg.
Makes me wonder if I'm a HUMAN PARACHUTE. Obviously there are folks out there getting more from the watts they have than I'm getting. Have any of y'all thought about this and/or done anything to get more efficient on the bike? More aggressive aero position maybe? Low rolling resistance tires? Clean your chain for once?
Let me know - I really need help!
BTW, here's the raw data if you want to play with it:
https://docs.google.com/spreadsheet/ccc?key=0Ap-T5i2jNxCQdFB3djB2Tl9zWEdCN0p4VkxZdXJrTHc
http://forum.slowtwitch.com/gforum.cgi?post=3499977
They collected data on average watts vs. MPH in their latest races, then plotted it out. I was shocked to find out how many riders post bike speeds of 23+ mph on about 3.2-3.4 W/kg. Same shock to see gobs of riders at 23-25 mph with average watts under 240. I have yet to convincingly break 22mph in a sprint or oly tri, and I tested FTP recently at 242W and 3.25 W/kg.
Makes me wonder if I'm a HUMAN PARACHUTE. Obviously there are folks out there getting more from the watts they have than I'm getting. Have any of y'all thought about this and/or done anything to get more efficient on the bike? More aggressive aero position maybe? Low rolling resistance tires? Clean your chain for once?
Let me know - I really need help!
BTW, here's the raw data if you want to play with it:
https://docs.google.com/spreadsheet/ccc?key=0Ap-T5i2jNxCQdFB3djB2Tl9zWEdCN0p4VkxZdXJrTHc
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Comments
In order to properly compare yourself to this data set, you need to create one (or more) data points and see where you fit in the graph posted early in that thread. Note that your stated w/kg is based on your FTP, NOT on your race day power, which will be lower.
I was interested enough in this to go back to my two best recent bike splits, and run the numbers. I used a PowerTap/Joule combo, as analyzed by WKO+:
Race Dist Avg Sp NP Wt in Kg w/kg = NP/Wt
Blue Lake Oly 23.72 21.8 193 65.9 2.93
IM Arizona 112.51 19.9 136 66.6 2.04
Both of these courses are essentially flat, so I was in aero position better than 98% of the time.
These numbers as best I can tell put me squarely in the middle of that data plot of Speed vs W/kg. So I'm neither a parachute nor a shiv. For reference, my w/kg @ the time of the Oly was 3.23, for IM AZ, 3.28.
I'd like to add a couple more points ..... I think it should be Average power and Not NP since its the AP that moves you down the road.... Also the weight of the bike should be added to the calculations because that 20lb bike is a much higher percentage for smaller people....The bike always gets left out in these discussions....
I couldnt get the spreadsheet to accept my data....
My IMFL data....
NP174 , speed 22.7mph , dist 111.7 , weight 118lbs , w/kg 3.25
Use AP of 172 instead of the NP and w/kg drops to 3.21
Then add the 20lb bike and the w/kg drops to 2.75
X3 what Al and Tim said...of course! I think the main reason it seems your numbers don't fit on the scatter plot is comparing race power (whether AP or NP...mine was only 1watt different on recent 70.3) to FTP. I plugged my numbers in from recent 70.3 and I am within the range of the scatter plot too (a little on the lower side, but I'm not in a particularly aggressive position (yet)).
It seems to me that the majority of data on this spreadsheet are either some bike freaks or they were racing shorter distances, or these data are from outdoor FTP tests, shorter TTs, etc.....NP or AP of 250-350 or more would mean these athletes have an FTP of 300-400+ if these data were from HIM or IM splits (or else they needed a wheelchair to finish the run).
However, you should be able to do a TT or FTP test outdoors (aero, disk wheel/cover, aero helmet, etc.) and see if you fit on the scatter plot reasonably well, if you feel like you are a sail! I definitely feel like a sail on my road bike now (esp if I'm on the brake hoods), once I experienced a TT bike.
Al, Paul and Tim made very good points. Read the Hierarchy of Aero thread on ST that Paul mentions... and then read it five more times and pay very specific attention to everything Jim Manton wrote. That dude is an aero and fit wizard.
His hierarchy is:
1. Position
2. Position
3. Position
4. Position
5. Position
6. Clothing
7. Helmet or wheels/tires
8. Helmet or wheels/tires
9. Clean front end (this could include aero bars, which may result in moving up this list quite dramatically depending on initial setup)
10. Hydration/Food setup
11. Frame
Michael, do you have any pics of you and your bike on race day? I think triathletes are generally very guilty of the following (not saying you are as I have not seen any pics):
Jim Manton has been mentioning for some time now that clothing is where the greatest future gains will be made. Clothing is something that triathletes have not paid the best attention to over the years. Tri tops, IMO, are generally terrible solutions. They generally don't fit as tight as they should plus the sleeveless design lends to less than optimal aerodynamics as there will always be drag associated with a sleeveless design. That goes for hydrodynamics as well. The sleeveless tri tops with pockets are horrible in the water assuming a non-wetsuit swim. I hate saying all that on EN because we'd all love to wear are kits all day and represent the team colors and all that. I know Rich cringes whenever I say stuff like this but science is science and facts are facts. I think the sleeved suits and tops that are coming out now are the best way to go. More aero plus they protect you from that big yellow ball in the sky.
I made a real conscious effort to minimize my rider profile over the last year or two. Here is me at IMFL this past November. Not saying my position is perfect but I've done a lot to keep within Jim Manton's hierarchy.
The point is well taken about race-day watts being below FTP. Checking a couple of sources about tri bike pacing turned up the following recommended percentages of FTP (sorry if I might have missed one on EN - still a noob flailing around on the site):
Source 1
Sprint - 95-100%
Oly - 85-95%
HIM - 75-85%
IM - 65-75%
Source 2
Sprint - 100-103%
Oly - 95-100%
HIM - 80-85%
IM - 68-78%
@Al, if I did the math right on your numbers, I had you at 91% for the oly and 62% for the IM, so your numbers bear out the pacing #'s.
@Paul, I read most of the Hierarchy blog and I get the main thing: Position is where 80% of the gains are to be had, but look into an aero tri suit for maybe a little more.
@Tim, after correcting for bike weight you got 22.7 out of 2.75 W/kg, and 22.7 out of 172W at IMFL. If I'm reading the scatter plot correctly, that puts you at the top of the speed-per-watt range. You must be doing something right! Anything special about your position that you work on?
@Bob, I don't have any pics at present. I'll also need to wait for warmer weather to get power data from a race (bought power meters this past fall after the season was over). I'll take a look at the slack position/loose clothes/extra crap issue in spring. You said you made a conscious effort to work on position over the past few years. How did you go about it? Is there something I can incorporate into every-ride practice?
Other than saying that position is most important, I didn't pick up any specific suggestions from Jim Manton about how to improve position. Anybody know of a blog of his I can check to look into this more?
Starting to look into race clothes now...
There is a new thread on ST about the recent aero camp which suggests that much of the other accepted aero logic may be right, or it may be wrong. Drag is really an individual thing that rquiures testing to improve.
I have heard the exact opposite... I'll have to go and try to dig up the old podcast that it came from... It said if you have an aero Helmet that was designed with a visor and you do not use the visor then you're messing up the aerodynamics so bad that you may as well just use a road helmet. Kind of like having a concave parachute on your face without the visor.
FWIW, I love my Rudy wingspan but was also considering going to an even shorter tail helmet this yr. I decided to pre-order their new Wing 57 with the massive EN discount. It has a visor and I plan to use.
You also might want to read the Aero Camp thread on ST regarding the Wing57. The conclusion out of that testing was (to quote one of the guys at the camp):
I think the general consensus when talking about tests with the Rudy Wing57 fell along these lines:
a. It's consistently faster than the Wingspan
b. It's normally not the fastest
c. Overall, it seemed a bit underwhelming given the hype it recieved
As Paul already mentioned, apparently the best tested helmet by far was the new LG P-09.
Every year I go in and either have a professional fit or play with a couple of more aggressive positions and see what works out. My position in that picture above is about as aggressive as I can get. I'm running the lowest bar/stem config on the new SC w/out spacers. I also have the saddle slammed all the way forward, which was more due to that particular saddle than anything else. I was able to fit myself on the new bike because the geometry of this bike is identical to the previous gen SC. I just had to make some tweaks because of the new aerobar/cockpit design.
It's little tweaks over time to improve position. I wouldn't have been able to use that position four or five years ago. It would have been very uncomfortable and probably a little scary.
Here are some more comments on the Wing 57 helmet testing from the Aero Camp:
The Wing 57 we had there was one without a visor. I believe 5 or 6 people tested it. It tested pretty well on some people and just ok on others. It was definitely faster overall than the wingspan though. Again, helmets are very individual, on one person it was close ( probably within the margin of error of the best helmet on that person).
And from Jim: "I'll leave the Wing 57 numbers to the campers. The star of the show was the Louis Garneau P09."
As to visors... the general rule is that visor typically add drag compared to sunglasses, but as testing shows "not every helmet tests faster without the visor, some helmets test faster with vs without." And from Jim again: "Brian is correct. In fact, the Javelin is typically better with the visor, as is the Giro Selector and Lazer Wasp. The P09 is better without." Also, from other threads, if you have an Air Attack aero road helmet then ditch the shield.
Now for the science from a Specialized engineer on why visors TYPICALLY add drag:
chrisyu wrote:
"Hey guys,
I don't want to jump into this discussion except to clarify the direct questions about our shield research. I've been MIA recently due to a busy few months so if I miss anything that I may be able to chime in on, just PM me to take a look and I'll get on it!
Anyways, what we have found is that a head is a fairly poor aerodynamic shape because it is a pretty good approximation of a sphere. Spheres are bad because (at the Reynolds numbers associated with the size of a human head and bicycle speeds) they tend to separate nearly at the point of max width/diameter and create a large wake region, resulting in high drag. Wearing a good aerodynamic helmet is actually faster than wearing no helmet since they shape the head into more of an ellipsoid than a sphere. Why do I bring this up? Because with the way visors are typically executed, the visor/helmet front end becomes closer to a sphere (by creating a smooth round surface from the front of the face onto the helmet surface) and separation migrates back out to the wide point - again, resulting in higher drag. We've found this in nearly every visor/helmet combination that we tested. In a way, it can be worse than wearing no helmet since we've created a sphere that is bigger than your head.
Now, to the point of why some helmets may contradict this and test better with a visor than without: The catch with not having a visor is that you have to manage the airflow inside and out the back of the helmet. With an open front, no matter how tight you wrap the sides of the helmet to the head, flow will enter. Unless the helmet has been designed to effectively evacuate this flow, this can result in higher drag. With some helmets, drag from internal flow stagnating can be higher than drag from adding a visor, so the net result is a visor is faster in that particular system.
Finally, specifically with the S-Works+McLaren helmet: the fastest configuration is with no eyewear. We realize almost no one rides without something over their eyes, but we wanted to be upfront about what the fastest configuration is. Next fastest is with sunglasses (this one depends on which model exactly with no real rule of thumb - but I don't recall testing a sunglass model that was slower than a visor on this helmet). Next is with a visor.
Sorry for the long winded response, but I like to get these things right/clear and with aerodynamics it's hard to be brief. Hope that helps, and again sorry for barging in on this particular thread!"
If I were retired, I know I would be doing stuff like that all the time. Just Sayin'
Seriously though, I've provided some snippets below from Bike Radar on how ERO Sports tests for drag. A more complete description is available from Triathlete at http://triathlon.competitor.com/2013/03/gear-tech/wind-tunnel-killer_71740. They note the biggest weakness of the Track Aero System is that it cannot test for yaw which is a real world circumstance.
------------------------------------------
ERO Sports uses the Track Aero System created by Canadian engineering firm Alphamantis that provides a rolling coefficient of drag, while getting ANT+ feeds of power and speed from a rider on a velodrome. The software also figures in rolling resistance, gravity and air density, based on a formula by Robert Chung.
The end result is powerful, actionable data.
For everyday competitive riders, this new service could be huge. For $800 for a two-hour session, a rider can test out a variety of positions and equipment on an indoor velodrome while getting a CdA (coefficient of drag x frontal area) every lap and the data in Excel afterwards. The implications are like a wind tunnel but, in many ways, better. While some wind tunnels sell tunnel time to amateur riders who want to refine their position, they don’t allow for actual riding. And anyone who has ever attempted to find an aero position knows that what's fastest isn’t necessarily comfortable or even sustainable.
The VELO Sports Center (formerly the Home Depot Velodrome) in Los Angeles is the first track to offer this service, in conjunction with fitters ERO Sports, Alphamantis and track owner AEG.
BikeRadar editors have seen a number of professional riders tuned for aerodynamics in a wind tunnel, only to revert to an old position when on the road.
But Manton pointed out that position and equipment gains are not equal across all riders.
“Aerodynamics is individual,” he said. “What’s faster for one rider may not be that fast for another rider, whether that’s a particular piece of gear or a particular position. Then the next question is, is that position sustainable? That’s where the role of a fitter comes is. It’s a blast to see what works for certain riders and what doesn’t.”
While I don't know enough about drag to say which is faster, I've found for my racing (any distance), it's definitely more comfortable to have the visor than the glasses. No ear pieces digging into my head and no headaches from trying to look under the frames ahead of me; all of which enables me to easily look forward.
Like we've said here about many pieces of equipment, including bikes, helmets and especially saddles, comfort is also a huge variable to take into account - and I'm sticking with my visor!