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Re: Another potential "flaw" in the study ... [Frank Day] [ In reply to ]
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Ah, I see what you're saying. Still, with the raw data I think all you could do would be to change the weighting of the time spent at each apparent wind angle. For example, he used a 30 degree angle for 5% of the ride. If I have a 30 mph 30 degree apparent wind, I'm either close to sitting still or that storm has a name. In either case, it's time for me to go home.

There is no way I could take that data and try to apply it to a real world race course. You or I might use different assumptions to define expected racing conditions but the results would still be so specific to those assumptions that the only conclusions I could draw would still have to be generalized ones like the ones I stated above.
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Re: Another potential "flaw" in the study ... [BillT] [ In reply to ]
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Bill T wrote: "There is no way I could take that data and try to apply it to a real world race course. "

Oh, I disagree. Although you personally might not, data exists regarding wind direction and speed at verious locals at various times of the year and day. Then there is the daily forcaast available the day before the race. some would find this exercise useful, challenging, and enjoyable. Without taking these variables into account, the current study under discussion is a good start but is pretty much worthless for making decisions.

With good historical data and weather forcasts, one should have a pretty good idea as to what the wind conditions will be like (direction and speed) at any particular part of the course when the rider is expected to be there and what speed the rider will be riding at that point (is it uphill or downhill, etc.) such that the wind conditions for the bike and rider could be pretty well predicted for the entire race. Take Hawaii for instance, the wind is pretty much the same year after year. It would then be a "simple" matter of applying this data to the air resistance data to determine the best race set up for that course on that day, if one is so inclined to do so. In regards to overall race performance, the effort involved in doing this would be much more worthwhile and cost-effective than the work involved to attain the money to save a few grams on the bicycle.

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Frank,
An original Ironman and the Inventor of PowerCranks
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Re: Another potential "flaw" in the study ... [Frank Day] [ In reply to ]
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The simplistic approach can work because although the drag numbers at a yaw angle may be a bit too high (since the same 30mph is used instead of taking into account "the real apparent wind", this can be compensated by adjusting the relative weight in the overall drag number of this specific measurement.

Also, with regards to the wind coming from all directions, aside fromthe fact that the apparent wind will almost always come from some portion of the front quarter, even if the wind is so strong that the apparent wind is almost from the side, the airflow is stalled at that angle anyway so it makes no real difference at that point.

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Gerard Vroomen
3T.bike
OPEN cycle
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Re: Another potential "flaw" in the study ... [gerard] [ In reply to ]
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I agree regarding the compensation except I didn't see this occurring in this analysis which is what brought on my original comment.

Next, the wind always appears to be coming from the forward quarter because we are almost always riding faster than the wind is blowing in the direction we are riding. (the old navy maneuvering board problem again) since we don't have the raw data we cannot see the relative effects of this side stall in the varous set-ups and the only effect that makes one whit of difference is the effect in the direction of travel. That is the criticism. The analysis as presented is only valid for one set of conditions and cannot be extrapolated to any other set of conditions. It may be valid for other sets of conditions but the data has not been presented that allows me to independently come to that conclusion.

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Frank,
An original Ironman and the Inventor of PowerCranks
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Re: Another potential "flaw" in the study ... [Frank Day] [ In reply to ]
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In Reply To:
I agree regarding the compensation except I didn't see this occurring in this analysis which is what brought on my original comment.

Next, the wind always appears to be coming from the forward quarter because we are almost always riding faster than the wind is blowing in the direction we are riding. (the old navy maneuvering board problem again) since we don't have the raw data we cannot see the relative effects of this side stall in the varous set-ups and the only effect that makes one whit of difference is the effect in the direction of travel. That is the criticism. The analysis as presented is only valid for one set of conditions and cannot be extrapolated to any other set of conditions. It may be valid for other sets of conditions but the data has not been presented that allows me to independently come to that conclusion.
Hi Frank

As a layman and trying to get the most out of JC's test I determined that adding a bottle/cage to a previously bare frame will reduce drag by 1 second per mile ... is this fair to say? I estimate a 25 second advantage over a 40k at my 26 mph pace, would you agree that this is pretty accurate based on Johns numbers?



Thanks



Gary
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Re: Another potential "flaw" in the study ... [TimeTrial.org] [ In reply to ]
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I would say that the "advantage" is dependent upon the wind conditions on the course you are riding. For instance, if your time trial course is an out and back and parallels the shore there in SD the wind is almost always going to be from one side or another so JC's assumptions do not apply to that course. I would look at the course you ride and see if the wind conditions are similar to JC's assumptions. If it is then those numbers may be good for you.

Further, the advantage or disadvantage may be different if you are a different body build than the rider he used in his test (although I think you are probably pretty close to his model). It would be great to have the data for a woman on a small bike where the size of the bottle is relatively large and a 200 lb six foot rider where the bottle size is a lot smaller, relative to the whole.

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Frank,
An original Ironman and the Inventor of PowerCranks
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Irrespective of anything else... [ In reply to ]
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...i'm surprised there isn't more discussion about the fact that the profile bottle is faster than anything else, and this is also the easiest set up to drink from and refill on the fly. (one assumes that syntace's jetstream would be equally as fast).

also, consider the discussion of why the down tube bottle is faster than no bottle -- the supposition that it pushes the air out and around the seat tube (in part) rendering the drag of the seat tube less meaningful. is it possible the front bottle does the same for the rider behind it? if so, then a bigger front bottle might be of greater value.

i remember the profile bullet bottle, which i believe got the heave-ho at ironman, and i believe the hed bottle may also have gotten the axe at that race, i'll have to go back and check. but perhaps these bottles are better yet because they'd presumable push more air out and around the rider.

the reason this is interesting is that it was always the guess that a trailing edge would be better than a leading edge, based on what both steve hed and john cobb thought a decade or so ago. therefore, the behind the seat "trailing edge" used by chuckie v quite a few years ago, with two holes in it to hold a pair of bottles, was thought to be faster (it looked like the trailing edge behind the saddle of a cafe racer motorcycle). now, i'm guessing a bullet shaped front bottle might be better.

Dan Empfield
aka Slowman
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Re: Irrespective of anything else... [Slowman] [ In reply to ]
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I have always thought that angling the aerobars way up and putting the hands in a "fist" or ball shape would allow the body to "hide behind" this small area and draft itself and direct a lot of air down and away from the torso. This configuration is what divers use for a "splashless" entry. This data reinforces my belief.

It is one of the reasons I asked T. Demerly to look at this type of position if and when he ever gets to the wind tunnel. such positioning would allow the rider to sit up some, to be in a more powerful position yet remain quite aerodynamically efficient.

Frank

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Frank,
An original Ironman and the Inventor of PowerCranks
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Re: Irrespective of anything else... [Frank Day] [ In reply to ]
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My take on your idea, FD, is that having the arms slanted severely upwards takes out much of the muscular leverage gained by the current straight out vogue. It particularly limits the core muscle groups' recruitment. While a few riders will be able to ride this way due to their particular body, most will, I believe, find themselves much less powerful. That loss would negate any aero advantage. I'm sure you remember the early days of aero bars. Almost everyone rode with them up and hands as close as possible. I had my old Scott DH's and then Profile clip-ons pointed high in the sky myself. My latest TT machine has my forearm centerline parallel with the deck. I feel much more able to use my core to support a powerful pedaling action. If it is less aero, I don't feel that. Things have certainly migrated the other way these days. Ullrich and Leder's positions are probably at the useful extreme. Most trackies are in similar positions on aero equipment.
Last edited by: TriBriGuy: Jul 9, 03 14:49
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Re: Irrespective of anything else... [Frank Day] [ In reply to ]
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For the discussion on forearm angle (zero, rising or down), there is already quite a body of work available. The old Cycling Science is full of it. The position with the hands lower than the elbows is usually frowned upon, but we have had riders in the tunnel for whom that is the fastest.
Doesn't make much sense to most people (or FOR most people), but sometimes that arm position has an effect on the shape of your shoulders. Of course breaking your collarbone can have the same effect.

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Gerard Vroomen
3T.bike
OPEN cycle
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Re: Another potential "flaw" in the study ... [Frank Day] [ In reply to ]
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"Oh, I disagree."

Trust me. I couldn't. Never underestimate my lack of knowledge and ability.

"Although you personally might not, data exists regarding wind direction and speed at verious locals at various times of the year and day. Then there is the daily forcaast available the day before the race. some would find this exercise useful, challenging, and enjoyable. Without taking these variables into account, the current study under discussion is a good start but is pretty much worthless for making decisions."


I race sailboats at various places around the country so I have a lot of experience with wind speed and direction forecasts. If you are lucky, they are accurate enough to get the right sails on the boat but that's about it. Even in the trade winds there is so much variation from day to day and hour to hour that such an exercise would probably be no more accurate than the percentage weights used in the article. Even worse, this is a race on land where topography plays a huge part. Have you ever seen wind swirl as it passes over a hill or veer on the leeward side of a clump of trees? One would need a weather station every hundred yards or so to measure the wind at that spot. Then the forward speed of the rider at each point on the course must be factored in. Of course, on race day the sun hitting all those cars in a normally empty field creates a 2kt thermal and blows the whole thing.

Would this exercise be useful, challenging and enjoyable? I'll give you two out of three. If all you want is an approximation based on a particular course, maybe I'll even throw in useful. By that standard, though, the original study based on an averagae of all courses would also have to be considered useful.

Here is a money-making idea. Email me if you want to form a joint venture to do it. Let's compile the side-wind data for various components like disc wheels, aero helmets, frames, bottles, sunglasses - whatever. We can then use historical wind patterns and topo course maps to sell "optimized equipment lists" to competitors. Just think, for only $150 we could tell everyone to spend $1,500 on new gearing, wheels, etc.
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Re: Irrespective of anything else... [Frank Day] [ In reply to ]
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"angling the aerobars way up"

i remember being at the texas a&m tunnel many years ago and this was tried. all the forearm angles yielded about the same drag except arms WAY up, with which the drag was lower. but it was a position almost nobody would want to ride.

as i recall, tho, colby pierce's arms sort of hide his body. but maybe i'm misremembering his position. he seems to me the one top time trialer for whom drag was/is the number one consideration, power coming second.

Dan Empfield
aka Slowman
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Re: Irrespective of anything else... [TriBriGuy] [ In reply to ]
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What is most aero may not be most powerful and vice versa although I don't see how the position of the forarms affects core power. I suspect you feel most powerful there because that is how you spend all your time.

I can only say that from my cogitating on this "problem", it would seem that the current vogue, except in the sense it presents a small frontal area, looks like it is designed to be as unaero as possible. The head and torso slanting up and the arms down and out all forming a U shape as if designed to catch as much wind as possible up against the body. Seems to me we should be trying to move as much wind as possible away from the body by making a "fairing" out of our hands and arms, not a scoop.

Now maybe the work has been done and my thoughts on this process are all wet, but the conventional wisdom certainly didn't predict the results of this test. I wouldn't be surprised if something better existed out there that gave a better combination of aeroness and power.

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Frank,
An original Ironman and the Inventor of PowerCranks
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Re: Irrespective of anything else... [Slowman] [ In reply to ]
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Slowman wrote: "all the forearm angles yielded about the same drag except arms WAY up, with which the drag was lower. but it was a position almost nobody would want to ride. "

Really!. What was so uncomfortable or strange about the position that someone couldn't or wouldn't do it in order to go faster in a race?

I envision the fist being just below the eyes and about 6 inches in front of the head as being ridable and very aero. Is that what you remember or was it something different?

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Frank,
An original Ironman and the Inventor of PowerCranks
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Re: Irrespective of anything else... [Frank Day] [ In reply to ]
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"What was so uncomfortable or strange about the position that someone couldn't or wouldn't do it in order to go faster in a race?"

when lemond was interviewed after the '89 tour and asked about the scott bars, his answer was, "they give me an extra point of leverage."

i think this is one of the elements of aero bars that gets lost in the discussion. but more to the point, that point of leverage itself gets lost when the bars are turned up too much. there are other elements that get lost as well, such as handling (odd turning radius) and comfort (can't rest on the bars if the bars are at such a steep angle).

so of the four necessary elements in tri bike fit -- comfort, power, handling and aerodynamics -- three are lost when the hands are too high. it was perhaps that same wind tunnel test or maybe another, when i saw kenny glah in the tunnel getting fitted. his drag was dropped from 7lbs to 4lbs and change. but he just couldn't ride the position. not comfortable, not powerful. he had to go back to the position with greater drag.

you see the best riders in the world often riding positions that aren't really that low in drag. lance and indurain are the two most recent that come to mind. they just don't want to give up the power position that a lower drag would require. i'm guessing these guys are 6 and 7 lbs of drag respectively at 30mph in a straight blow, vs. colby's 4 lb. or so.

but when i look at millar, and ullrich (as of today's coverage) i see both good positioning and good aerodynamics. as fast as some of these really fast guys are, i still think there's more on the table. ullrich obviously thought so, we'll see how that works for him in the ITT stages.

but i do believe that you must keep your power and comfort intact. you can't give those up for aerodynamics. you can argue all you want theoretically, but the good riders from zack to spencer smith to lance to big mig, have found this to be the case. and this is the trick in tri bike fit, to work just a little harder, be just a little better, at your craft, and find a position that is BOTH aero AND powerful/comfortable.

Dan Empfield
aka Slowman
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Re: Irrespective of anything else... [Frank Day] [ In reply to ]
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FD, The higher the arms, the more acute the inside angle at the elbow. This takes the triceps further out of its power range, and imbalances the input from bicep and tricep. It also slightly changes the angle of the upper body and places greater demands on the serratuus region for stability. This is why Dan's emphasis on a 90deg shoulder angle is so important. Any greater angle takes all these opposing muscle groups out of their optimum positions for leverage and stability.

You may not notice the contribution of all these muscle groups cruising along fairly relaxed at 20-24 in an IM, but cranking along at 30+ like these guys requires significant input from the upper and core body. Even Lemond claimed that his greatest benefit from the bars was more leverage than aero.
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Re: Irrespective of anything else... [TriBriGuy] [ In reply to ]
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Lemond may have claimed that the benefit was more leverage than aero but I don't believe it. If there was an uphill time trial up Alp d'huez how many of those people would put their aero bars on for the increased leverage? Not a one I suspect. If they want to increase the power they open up the hips and if they want to pull on something they are better off doing so on the handlebars proper than on the end of a 10 inch tube. It is not necessary to ever pull on the bars to increase power in the saddle as we never push down with enough force to raise our bodies off of the saddle. The bars are used, i suspect, in this situation simply for stabilization and psycholgical reasons and not for adding any power beyond the legs. "I feel powerful, therefore I am."

Of course, positioning should take into consideration as to what it does to power. Unfortunately, I don't know how anyone can look at a position and say "this hurts your power more than it helps your aerodynamics." especially when the range can seemingly vary per Dan and JC from 4 to 7.5 lbs force on the aerodynamics part of the equation. How can we know any position cuts the power in half? Riders may feel uncomfortable with a position because it is so different but if they spent some time with it they might learn to like it (or, they might not).

One thing almost every PowerCranker learns is that their old "aero" position robs them of a lot of power. What I think this study (and the A&M wind tunnel data Dan mentions) suggests is that it may be possible to open up the hip angle to a more open position and then do some other things to improve aerodynamics in order to keep the power up without sacrificing a thing in aerodynamics. Many PowerCrankers are right now struggling to get down into their old aero postion and now we find it may not be optimal. Is there a better way, that is the question I think that must be asked. If I were them I would be experimenting right now to see if I could change my hand position some and cut my wind resistance in half (or, maybe, only 80%) while keeping my hips open and powerful! If we can cut the aerodynamic drag losses in half by some simple positioning changes and maintain the current power constant most of us should be able to gain 4-5 mph in TT speed and doesn't cost a dime. This seems like something worth pursuing.

One thing that seems to be happening here is there seems to be a lot of emotion invested in the old positioning whereas one thing that the JC study shows, almost any conventional wisdom can be proven wrong once it is actually studied. Actually, I am not sure the JC study proves anything but it suggests it and should be independently verified before considered proven.

One thing I will agree on, the rider needs to feel comfortable with the setup on race day whether the numbers say it is optimal or not.

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Frank,
An original Ironman and the Inventor of PowerCranks
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Re: Irrespective of anything else... [Frank Day] [ In reply to ]
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Rotor cranks (www.rotorbike.com) allow riders very minimal break-in time (1 ride versus 6 months with PCs), and, using mechanical devices, provide an average of 2 minutes faster times in a 40k time trial without having to sacrafice the aero position and they are made to race on. They are also only 250 gms heavier than Dura Ace.

Worth checking out as an option for PowerCrank users who cannot find optimal aero position while riding PC's.
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