Doge

Also the most aero position at 25mph may not be the most aero at 35mph.
So I'd prefer a test full out than at 75%

Doge

No. I would use race speed and the clock. Not a PM.
As power changes the forces (weight on arms, core) change. In a longer event that matters a whole bunch. In a 4K, as someone mentioned it may not matter. The bottom line is what works best for an event.

As speed changes so do the aerodynamics. A graph of a rod at 20mph, 30mph and 40mph will not look the same as a graph of two rods - with rod #2 drafting rod #1 at the same speeds. The vortex created by the leading surface extends further as speed increases. If surface #2 is outside that vortex at 30mph, but in it at 35mph that is useful and reduces drag. That would never have been seen at 30mph.

Anyway, I would guess starting points. It is educated guessing. I would not use 75% power to determine what is best for 100% event.

The testing thing...We tested a whole bunch...blood panels, SPO2, lactate levels, VO2 etc. About age 16 he said no more. USAC coaches wanted power, miles etc. They didn't get it, I'm not going to.

I should not have mentioned HR. I use it for my kid because I know what it means. I esp use morning resting HR. So for him - HR is a useful number for me.

taras0000

Not the placement of the hands, but the arms. I'm talking about where the elbow in in relation to the body, specifically the hips. By flexing the elbow, you can move the arms up or down, and still maintain the same hip angle, and torso, and upper arm angles. The position is the same, you've only hidden your face. BUT by moving the elbow pads, the rider is forced to change position. This is the case when you are making any angular changes across a single unsupported joint. With two unsupported joints, you can move things in parallel.

Look at those pictures again, and note where their elbows are in relation to their body for each of the events. Elbows further forward and slightly up for the hour, back and down for the pursuit.

taras0000

Doge, I'll leave you with these thoughts.

If your son doesn't like being tested, then maybe don't test. It sounds like he's burned out with that kind of stuff. If he's not able to ride and race much, then maybe just let him ride as he sees fit, on his terms.

The route that you plan on taking to achieve your means is going to be littered with a whole bunch of guess work and unnecessary time spent testing, which is going to be a long drawn out process, and seeing as it's all guess work, your results may be sub-par, furthering his dislike for testing. With the method I had outlined above, you can accomplish what you want with only one or two sessions, and they can be spread as far apart as you like, to minimize the intrusiveness of testing. Then you'll be done, and he can get on with just riding how he likes, or whenever he can.

Like I said before, you already seem to be set in how you're going to achieve this. You're ignoring good advice. It's no skin off my back, and I don't take it personally, but advice isn't being offered for your benefit, but for your son's. If you think you know better, then just go ahead and do what you're going to do.

Dalai

Field testing aerodynamics indoors (empty velodrome) is useful for testing CdA. CdA is CdA regardless the effort!. If a rider changes their position to a less optimal one when going full gas, it is in their interest to work on maintaining that optimal position at 100% to be as slippery as possible.

You can go and make all the assumptions you like and not listen to the large amount of good advise here and not test. But having personally spent time in the wind tunnel assumptions are just that, and what works for the individual can be unique and go against the considered norm.

Doge

In systems where a trailing part can "draft" a leading part that drafting may take place at a higher speed where it does not at a lower speed. We know the down tube breaks the wind. The air comes around the down tube and then hits the seat tube and again breaks the wind. So in effect you have 2X a single tube CdA breaking wind both with downtube and seattube.

But if you look near the BB the downtube breaks the wind and the seat tube is drafting the down tube. So you do not have a 2X tube CdA at that point.
As speed increases this drafting effect takes place farther up the seat tube. So the system CdA changes based on speed.

Similar for hand/elbow position. Hands on the extensions break some wind. Slower speeds there is no draft benefit from the hands and you would get one CdA number for the whole system. At higher speeds in certain positions the face may draft a bit off the hands - a different CdA.

Anyway, I'm not ignoring anyone. I'm taking input from folks I think know a lot more about track than I do.

carleton

You'd be amazed at how common that is with regards to track racing.

Seriously, I'm not kidding. Track racing seems easy, but it's not. Simple: yes. Easy: no.

Golf is a simple sport...but it's not easy.

It's very common for people to think because track bikes are very basic and track events are straightforward, that if they've figured out road racing then track should be a piece of cake. Easy-peasy. Like road racing is harder than track, so if you are decent on the road you'll clean up on the track.

When roadies come over to track, they experience a brief period of success. This is because they have a good level of fitness but are still relegated to racing newbie racers in the lower categories. They are simply winning because they are racing physically weaker riders, not because they are great trackies themselves. Things change when they encounter riders who are similarly fit but have been racing on the track for years. This is especially true with mass start track racing.

Track racing and road racing are related, but not how one might expect. Track racing is generally considered the training ground for making great roadies, not the other way around. Just about everything you learn to perfect on the track will help you on the road, carrying a high cadence, drafting, holding a line, riding in close quarters, recovering on the bike, bike handling, etc... I've seen competitive crit racers in my area use track racing as training to give them a competitive edge in crit racing. Racing on the track forces them to do things that they don't have to do in crits. Many great roadies started on the track.

Think of track racing as a more distilled, pure form of bicycle racing and road racing being similar but with a lot more variables.

Dalai

Why are you concerned with tube shapes and CdA? Unless you are testing different frames, how the frame tubes behaves at different speeds is mostly irrelevant to the testing.

The focus is the person as that accounts for 70-80% of the total! The goal is to lower the overall value and that is primarily done by changing the position.

Doge

Testing frames (several options) and air speed affects the best CdA position.
I will likely use the TK2 this year per the above advice.

The goal is to get in this program in 3-4 years: Air Force Sports

So the scope of my posts is not about track all disciplines, rather aero position (which is why I posted on this thread), bars, for the 4K (and bike).

taras0000

If you're going to be speculating about aerodynamics that much, to that degree of detail, then just pony up for windtunnel time. Seriously. You've been given the best recipe for finding out what you want without using a tunnel. Clearly this is not satisfactory to you. Just book some tunnel time and you'll get what you want.

In a separate thread, I had mentioned to someone that what they were doing is like chopping down a tree. The problem is, you are over-analyzing this thing, especially if you have 3-4 years to figure it out and get it dialed in. You're trying to figure out the best grind angle to put on the axe, and wondering how to do it in the best possible way, by taking into account every possible detail that may matter, with no regard as to how trivial it may be. In the time you spend trying to figure out how to sharpen your axe, someone will have come along, spent 2 minutes putting an edge on their blade, and already chopped down the tree.

taras0000

The seat tube doesn't end up the in the draft of the DT, or HT because the riders legs and feet are churning the air in front of the seat tube, creating dirty air.

You're focusing on things that don't matter, or matter so little as to not contribute to the system or be lost in the noise. You're focusing on the 1/2% that comes after all of the things we have told you about. Those things will take care of 98% of what you want, all you have to do is implement them. Once you've solved 98%, you start tweaking the last 2%.

Doge

I think you got my point. If you take the picture of Tony Martin (it looks like Tony) at the bottom picture https://www.bikeforums.net/19062923-post78.html in his now disallowed arm position, at a slow speed his biceps and face may not be getting much a draft from his forearms but at higher speed they might. I'd want that tested as close to race speed as possible - if it were a legal position.

We agree they are the small % areas, but I think they matter. I came to this thread to discuss aerobars and position. That in itself implies details. There shouldn't be any frustration that I'm not paying attention to the big stuff because I am focused on the topic - even if it is the 1/2%. Sure I'm OCD. I also do listen to the advice, but please don't expect a linear approach where we do each thing at once and come back for the next. There are too many parts to look at things one-at-a-time and then changing one thing, may affect another. I can think of a pile of coaches we've hired and another pile that give advice over the years, so I'm not anti coaching, or listening.

Junior has shown already to be one of the fastest juniors at shorter TTs, TTT and track Team Pursuit. He's won by only .1% before, so we'll take the 1/2% all day. Right now, it is not so important as many things are new. There is college, lack of sleep and lack of proper training and eating. I'm just investigating what I can now. Some for nostalgia (I'm sparing you most the pictures and video), but most for exploring new opportunities.

carleton

Who is your son?

Doge

The Official Website - USA Cycling
There is lots of data I have from training, segments in the race to indicate that 5K distance is his best.

taras0000

It also implies working on a good foundation to figure out what details to focus on.

This is the whole reason why you focus on the big things first and get them sorted out, because the changes that come after are small. If you focus on a detail, then an important (or large change), can completely erase all the time and energy spent on refining that detail. It's not about focusing on the things that CAN make a generic .1% difference, it's about focusing on what WILL get you that marginal gain. You can keep asking questions all you want, but you won't gain any knowledge, or be asking any useful questions until the big things are taken care of. Aerodynamics are highly individual.

How about you tell us what you do know about his aerodynamics, because at least then the discussion can move forward in a productive direction.

Doge

I misunderstood this post and took it the wrong way as a challenge. Therefore my response was a rant. Sorry others missed it.

carleton

I don't know, man. Those gadgets don't look too aero to me

taras0000

I think you misread my post. I meant your son's aerodynamics, not aerodynamics in general. I don't get into pissing contests, not do I look for them. I have enough people at work who look for them. Great resume. It's impressive (and I sincerely mean that). If a hatchet needs to be buried, I'll throw one into the dirt right now.

I did see the video and the results. Videos and results show his current ability, but are really only a small look into what your son is capable of as far as improvement without knowing other things about him. You've got questions, we may have answers. The problems arise when people ask highly individualized questions, yet we don't know enough to give an answer like that. Other times it's when someone is looking for help, is given the right advice, but the person decides (or gives the impression) that it's not good enough. I think that has happened here (even if it's just between you and me).

So to try and get us back on track, the questions I have for you are:

What do you know about positioning that has already worked, or had good results for your son?
What sort of process do you intend to undertake to find his optimal aero position? (This is with respect to his dislike of testing)

Arm chair "coaching" from afar may not be able to solve certain specifics, but there may be other wrinkles that we can iron out for you.

taras0000

I dunno. That servo from the Hellfire missile could be used in an "active aero helmet" where the tail adjusts to the yaw angle of the wind.

Doge

Well simple word was missed - "his". I was no so good at English. I apologize, I read it as a personal challenge and I was wrong. I'll go edit and delete most of what I posted as it is not relevant and, well based on my misunderstanding.

To answer what you really asked and re-asked. I think he is very well tuned on the road bike - as slippery as any and more so.

His position works now but in exchange for being a bit more slippery I think he is too far down and loses a wee bit of power. So I question if he should be higher and pick up a bit more power or as low as he is. As track speed is much higher, maybe that is bad. I get the idea about testing here. There were issues this year with sickness recovery this year and fatigue on longer TTs/going out too fast.

Hear are my thoughts on process. Go TK2, Track Zipp wheel, trispoke and as he has std stem just go with it initially using his TT setup. Get him on the track and see if a local (USAC) coach want's to tune him. Then start flipping into aerobars. I expect as power is higher, there may be some adjustment to the front. Most TT power is in the 350W range, I think track will be much higher. This is also 6,000 ft which does not affect him running (for time) and so I think he has cardio top end to spare. I have adjustable stems and he can use those.

But this is early. I'm not even sure it is going to happen.

taras0000

He might not be too low. A lot of Kilo riders are super low, the difference is that their elbows are closer to their body than someone doing a pursuit.

If you are able to bring his elbows back from his standard Road TT set up, so his elbow are under his ears, or slightly behind, by using a shorter stem (20mm) then I think this is a good place to start. This will only raise his shoulders a tiny bit, but will allow him to use his back muscles and core to brace himself to output more power. It's also the least intrusive change.

On a side note, I liked your "rant". That was some really cool stuff.

700wheel

As you indicate it is inefficient to change one variable at a time. You can change two or more variables at a time and obtain the effect on performance using a Design-of-Experiments test. But in any testing you do you should record environmental conditions at the time (air pressure, humidity, temperature); the environment can effect on performance.

warx

revisiting old thread...

I'm building a track bike (for Hellyer 335m concrete) and have 3T Scatto LTD drops. In one more year I'll be doing 500m and 2km pursuit (50yo). Figure for 500 the drops have no disadvantage but need aeros for the 2km pursuit. Tend to muscle the bars so worried about thin alloy bars or lightweight carbon. It's hard to tell from these bars which are strong and rigid and which are good for Ironman etc.! Definitely like the big turned up ski-tips too. I could go steel and clip-ons but does not seem optimal for 2km plus all steel are 26mm - although I guess these bars would have dedicated stem anyways.

rensho3

Look into the Pro Missle aerobars. They are light, but I think you would have to be king kong to break them.

warx

Yeah - those are definitely top of the list. Trouble is (as mentioned before) it's a investment if they don't work. Maybe I can find a used set that I could at least re-sell w/out a big hit.

I see a few Profile Design used ones on ebay. I can't tell if they're suitable for the track short efforts. Also many have integrated stems and again I just don't know if this is good or bad for this application!