Ask me about A2 Wind Tunnel! (Page 2)

Do you feel like you lose any power going into that optimal drag position?

Do it "seem" like it's tougher to breathe in that position or is your hip angle open enough?

In the mantis position, you look like you're sitting more toward the back of the bike.  Did you move the seat or just adjust where you're sitting?

Power was kept constant in position changes, it's something we watched pretty closely.

It actually feels a bit easier to breathe, but that could be all in my mind. It was not noticeably worse for sure.

The seat was never adjusted. Possibly just when the picture was taken, possibly a side effect of the position change or it's also possible I slid back some as the day wore on.

watts?

I was holding 200'ish for each repeat (after the first couple... it's hard not to pedal HARD when that fan comes on)

whoops, sorry my bad. I didn't test a stem mounted one (they nor I had one)

I tested

Torpedo btween the bars

Virtue Bottle

Bottle on back

Bottle(s) behind saddle

Ah, thanks.  I talked to the speedfil guys and they said that a torpedo mount (on flat bars) tested well, but a stem  mount tested slightly better, something about breaking up the eddy in front of the chest area.

Leego

I know you have modified your virtue bottle a little to close up the gaps. Do you have any pics of it on the frame and what did you do to modify it?

Great thread!!!

What was the drag difference between 1 or 2 bottles behind the seat?

THIS is the real question right here.

this is the best picture I have of it sitting in the triangle. (sorry)

Basically I drilled extra holes in the virtue cage and mounted it as low as it would go so that it fits flush. The only thing you'll have to do to get it like that is either dremel a little extra around the holes you drill (so the heads of the screws don't sit too far out, keeping the bottle from fitting)

About 60g higher than with nothing at 0 yaw and about 45g higher at 10 - that was with 2 bottles (I didn't test just 1)

Curious - why didn't you test the lieto style bottle mount (similar to your picture above)?

I tested bottle placement toward the end of my time, so I tried to crunch as many *largely different* things as possible. Jim (O'Brian - the fitter on hand) was pretty stalwart that that sort of placement (lieto) would be better for me than the two cages, so we just moved on.

I was thinking more relative to your capability (should have specified that, sorry). Sound like you're putting out a little something if I remember right.

they just told me to ride at what i felt like I could duplicate 20-30 times for ~2' each test. Actual power wasn't as important as it being consistent throughout. The first two runs got trashed because I was jumping around too much (it's hard not to pedal HARD when those fans come on) and the last 7 or so were a bit uncomfortable. Any more tests would probably have been marred by my tiredness.

Chris, that looks like a lot of fun to have access to a world class aerodynamic facility.  You are the first person I know of to have done it.  You are certainly the first to have written it up so thoroughly on this forum.   Thanks for putting up your experience.  I have enjoyed reading it.  I wish I could do the same. 

Some time or another, we should try to get together.  I am in Oak Ridge.  We may have some mutual acquaintances.

Glad you have found it interesting. It's something I've wanted to do for a long time but just never seemed to have the $ to do it. I was planning to buy a new bike, but some friends convinced me that I'd be better off just going to the tunnel instead... so that's kind of how it came to pass

And certainly, we surely are around some of the same races from time to time.

Leegoocrap - 2012-06-22 8:08 AM
Almost forgot, I had a picture in my BT kit. (Ahem, hey guys, can we get a BT one piece??? I don't want to say this kit tested sllloooowwwwww.... but...well... it did )

Is it assumed that any two piece will test slower than a one piece then?  Gald I'm in a one piece....

GoFaster - 2012-06-22 9:00 AM

Leegoocrap - 2012-06-22 8:08 AM
Almost forgot, I had a picture in my BT kit. (Ahem, hey guys, can we get a BT one piece??? I don't want to say this kit tested sllloooowwwwww.... but...well... it did )

Is it assumed that any two piece will test slower than a one piece then?  Gald I'm in a one piece....

It most likely has to do with the pocket structure. The BT kit has pockets closer to a cycling jersey, whereas the DeSoto is very tight in the rear pockets. The break between shorts & top is also probably a little of it, as covered skin is always faster than just skin.

I've pretty much fully adapted to the position change... as a matter of fact I've seen a few extra watts since the change (I would say it has to do with the relative ease to "tug" on the bars / keep myself on the tip of the saddle at higher watts.)

Handling in the "Mantis" position is just a bit touchier. Although mine isn't that high of a rise (therefore it's just a bit different than flat) I could see how somebody who had them very high (Landis / Tollakson 'ish) would have some trouble steering efficiently.

It's been a Pain in the butt to find a 0'ish stack dust cap to get the maximum drop (in the pictures above there was *no* dust cap, just open bearings.) I've resorted to crafting my own. On my 3rd carbon fiber one now, still haven't got one that looks "perfect." :P

I also changed the position to the same on my trainer bike (my S32) although it has S-bend bars instead of ski bends... this makes it tougher since my hands are bent a bit unnaturally... going to pick up some cheapy ski's at some point. That said, I rode it just fine in my sprint last weekend

All said, I'm happy with (most) everything about the trip.  I feel like I screwed up some things in the tunnel that didn't let me squeeze the absolute maximum out of my time... but that's part of the first time I suppose. I would love to go back at some point and test some more things that I ended up questioning after coming home.

I think I may have some lying around (off an old P2C).  If interested, PM me and I'll check them for details.  I will give you a good deal if they match what you are looking for.