Interesting Plasma Premium Aero Test Results - Updated w/Numbers

Triathlon Forum
1

Essentially the test was this:
Athlete’s original position is significantly lower than the Plasma Premium will allow with the Tri stem.The TT stem does a good job of matching the athlete’s fit coordinates, but disallows the use of the integrated hydration & nutrition set up.The question we wanted to answer was which would be faster: Athlete’s best position using the TT stem without the integration hydration, or less optimal position, but use the integrated hydration we believed would lower the bike’s drag? In other words, how much would the drag gap close by using the integrated hydration?

The numbers were interesting, and a little surprising, though I don’t want to be deceptive; position trumps everything else! Still I wonder if anyone has Plasma Premium numbers they’d like to share, whether it’s wind tunnel, velodrome, or outdoor VE testing regarding the integrated hydration system both installed and removed from the bike in the tri set up? I realize that’s pretty specific, but I’ve never seen any numbers posted, and there might be a good reason why. Anyone care to help out?

Edit: Numbers and photos now posted…

http://i66.tinypic.com/2ep7xaw.png

Run #1 - With Front Hydration (including bento and straw): .2721
Run #2 - Remove Front Hydration & bento: .2702
Run #3 - Re-Do Run #1 .2719
Run #4 - Re-Do #2 .2692

Straw could be having some effect, but I’ve tested straws in the tunnel and on the velodrome so many times and they just don’t seem to show up in the results with an athlete on the bike. The top of the hydration system could be disrupting airflow a bit. Much cleaner over the stem without it.

Additional:

Lower position with TT stem: .2580
LG P09 v. Rudy Project Wing 57: .2490

Yep, big difference in helmets, but to be fair, we used a med P09 which is a bit small for the athlete, so a large would likely be a watt or two slower. Still, not surprising. Friends don’t let friends use Wing 57’s; at least without testing first.

2

Not what you were asking for, but my instinct is that the integrated hydration is worth ~1-2watts for the Plasma Premium. A position change could easily be >5watts.

3

I’ll post the numbers here in a few days but, based on previous numbers from properly placed hydration systems like a Torhans Aero30 or a low mounted Profile FC35, I really expected the integrated components to significantly lower drag, which is why I believed it would be an interesting test. I thought the drag gap from the 2 positions would be closed up a bit. Didn’t happen. In fact, it was worse with the integrated hydration by 2-3 watts. Results were repeatable.

Now, I also realize that front bottle probably does well at yaw, but now I have to wonder how much? Probably not as much as I thought.

4

Did said athlete test TT stem with a Torhans or other aero-positive hydration?

5

I’ll post the numbers here in a few days but, based on previous numbers from properly placed hydration systems like a Torhans Aero30 or a low mounted Profile FC35, I really expected the integrated components to significantly lower drag, which is why I believed it would be an interesting test. I thought the drag gap from the 2 positions would be closed up a bit. Didn’t happen. In fact, it was worse with the integrated hydration by 2-3 watts. Results were repeatable.

Now, I also realize that front bottle probably does well at yaw, but now I have to wonder how much? Probably not as much as I thought.

I think you have to think about it in terms of what sort of head tube profile the front hydration is fairing. Caveats about the eyeball wind tunnel aside, the Plasma 5 Premium’s head tube in UCI mode looks pretty aero. Very comparable to a Speed Concept.

6

We did one quick BTA test with a standard bottle, but we had run out of time to really get into it. That’s something I would’ve liked to have done more given the surprising results.

7

Agreed, and the tri stem without the front hydration is really clean, too. I was just surprised by the drag increase, but perhaps I shouldn’t have been. Let me put together a side-by-side photo comparison real quick and post it up with the numbers.

8

A previous post asked whether an airfoil (s) can stall at zero degrees. I think you’ve found one.

-KQ

9

Doesn’t surprise me really. Most of the D2Z lot on the Plasma 5 are using the TT stem.

10

Well, yeah, going to the TT stem and lower position was an obvious one if that’s what you mean. It was the decreased drag from removing the front hydration, when we’ve see so often “elongating” the head tube with something like an Aero 30 can significantly decrease drag, that surprised me.

Now I can’t wait to test the Aeria bar and front hydration. Not exactly apples to apples, but it has my interest.

11

to be clear, are you saying that:

  1. no hydration at all is slightly faster than w/integrated front hydration? and you’re surprised, because you thought front hydration would test faster than no front hydration. yes?
  2. lower position is better than taller position, i.e., lowering the athlete with TT stem is faster than athlete with tri stem, the tri stem resulting in a taller position?
12

Yes, based on results from previous testing, I would have thought the integrated front hydration would actually lower drag. Mount a Torhans Aero 30 or a Profile FC35 properly, and you’ll reduce drag by 5-10 watts (10 would be rare, but 7 or 8 we’ve seen often). This particular gentleman purchased the Plasma Premium hoping to use the integrated hydration system, but after his fit it was evident the Plasma would not allow him to get low enough with the Tri stem; only the TT stem would work. Thinking about it, I wondered if the integrated hydration might lower drag enough that it would close the gap between the lower position, which would obviously be faster drag-wise, and the higher position the Tri stem would demand? Fun test! It’s just the results that surprised me. Certainly not the first time I’ve been surprised by a result.

13

Yes, based on results from previous testing, I would have thought the integrated front hydration would actually lower drag. Mount a Torhans Aero 30 or a Profile FC35 properly, and you’ll reduce drag by 5-10 watts (10 would be rare, but 7 or 8 we’ve seen often). This particular gentleman purchased the Plasma Premium hoping to use the integrated hydration system, but after his fit it was evident the Plasma would not allow him to get low enough with the Tri stem; only the TT stem would work. Thinking about it, I wondered if the integrated hydration might lower drag enough that it would close the gap between the lower position, which would obviously be faster drag-wise, and the higher position the Tri stem would demand? Fun test! It’s just the results that surprised me. Certainly not the first time I’ve been surprised by a result.

thanks.

i spent a lot of time with that bike. built one from the frame up. i think it’s a very well constructed bike, the hydration system inclusive. i think that front hydration systems, as often used, are a net negative, aerodynamically. down on the frame? not so much. up there? hard to make that dog hunt. aerodynamically.

so then you have to ask yourself about function. where does that system function best? because, the point of the system is to hydrate. unless you’re not drinking at all and you just want it on there for the aero benefit.

there have been front hydration systems designed for their aero benefit (the old PD bullet) that were deemed illegal (irrespective of whether they worked). in my opinion, a properly functioning front hydration system that was only aero neutral is pretty darned good.

to put it another way, aside from the fact that this bike won’t get low enough (i’ve written about this a lot), let’s pretend that this person’s position, with the tri stem, was correct. what would you use in place of this hydration system? because, if it’s a frame mounted system, that’s not as efficient, for me, as a refillable between-the-handlebars system.

it’d be interesting to check out canyon, etc., to see how the front hydration systems themselves test like, on and off the bike.

14

Yes, based on results from previous testing, I would have thought the integrated front hydration would actually lower drag. Mount a Torhans Aero 30 or a Profile FC35 properly, and you’ll reduce drag by 5-10 watts (10 would be rare, but 7 or 8 we’ve seen often). This particular gentleman purchased the Plasma Premium hoping to use the integrated hydration system, but after his fit it was evident the Plasma would not allow him to get low enough with the Tri stem; only the TT stem would work. Thinking about it, I wondered if the integrated hydration might lower drag enough that it would close the gap between the lower position, which would obviously be faster drag-wise, and the higher position the Tri stem would demand? Fun test! It’s just the results that surprised me. Certainly not the first time I’ve been surprised by a result.

thanks.

i spent a lot of time with that bike. built one from the frame up. i think it’s a very well constructed bike, the hydration system inclusive. i think that front hydration systems, as often used, are a net negative, aerodynamically. down on the frame? not so much. up there? hard to make that dog hunt. aerodynamically.

so then you have to ask yourself about function. where does that system function best? because, the point of the system is to hydrate. unless you’re not drinking at all and you just want it on there for the aero benefit.

there have been front hydration systems designed for their aero benefit (the old PD bullet) that were deemed illegal (irrespective of whether they worked). in my opinion, a properly functioning front hydration system that was only aero neutral is pretty darned good.

to put it another way, aside from the fact that this bike won’t get low enough (i’ve written about this a lot), let’s pretend that this person’s position, with the tri stem, was correct. what would you use in place of this hydration system? because, if it’s a frame mounted system, that’s not as efficient, for me, as a refillable between-the-handlebars system.

it’d be interesting to check out canyon, etc., to see how the front hydration systems themselves test like, on and off the bike.

Yes, I preach this all the time. Everyone gets so focused on placing their hydration systems (and everything else) in the most aerodynamic position possible, but forget about how they will use said systems and how that might effect their overall performance both aerodynamically and their ability to hydrate or get enough calories. The more convenient you make it, the less you have to contort your body to get to what you need, the faster you’re likely to be overall.

I might be able to get my hands on a Canyon with front hydration.

15

i think that front hydration systems, as often used, are a net negative, aerodynamically. down on the frame? not so much. up there? hard to make that dog hunt. aerodynamically.

Why do you think this? I think you have it backwards…

16

i think that front hydration systems, as often used, are a net negative, aerodynamically. down on the frame? not so much. up there? hard to make that dog hunt. aerodynamically.

Why do you think this? I think you have it backwards…

i well may. but perhaps not if jim’s testing is any indication.

i think most front hydration systems are built around the bottle. some kind of bottle. most often just regular water bottles picked up and discarded at aid stations.

17

i think that front hydration systems, as often used, are a net negative, aerodynamically. down on the frame? not so much. up there? hard to make that dog hunt. aerodynamically.

Why do you think this? I think you have it backwards…

i well may. but perhaps not if jim’s testing is any indication.

i think most front hydration systems are built around the bottle. some kind of bottle. most often just regular water bottles picked up and discarded at aid stations.

To be clear, most of our testing up until now has shown certain systems to lower drag when installed properly. These would be the bottles that hang below the extensions (Torhans, Profile FC35, etc.). In fact, we have a boat load of data on this, which is why I was so surprised by the results. I expected the Scott’s system to decrease drag thereby closing the drag gap I knew would be created by the position change. I figured if it closed it enough, it would be worth staying in the higher position and using the bottle. Not so much this time.

The shape of a BTA, a true BTA, doesn’t much matter since it’s really not exposed to the wind. I always find it funny that many of these bottles are aerodynamically shaped. Why? A regular water bottle can be replaced very quickly at an aid station. No refilling before you leave the litter zone; just replace and dump. Which would be faster? Re-filling the bottle or replacing it? To drink from a straw doesn’t require much change in position while grabbing a bottle out of the BTA holder and drinking does. Still, how much time are you giving up re-filling that refillable bottle as you go through an aid station v. quickly grabbing and replacing? It all might be aero neutral in the end, or one might be more aero through the course of a race.

I agree, though, that how you use the bottles, or even the ability to use them so you stay hydrated or get sufficient caloric intake, is an important part of the set up process that can be overlooked. It’s easy to get caught up chasing the lowest CdA. I don’t know of anyone that hasn’t fallen into that trap at some point eschewing practicality.

18

i think that front hydration systems, as often used, are a net negative, aerodynamically. down on the frame? not so much. up there? hard to make that dog hunt. aerodynamically.

Why do you think this? I think you have it backwards…

i well may. but perhaps not if jim’s testing is any indication.

i think most front hydration systems are built around the bottle. some kind of bottle. most often just regular water bottles picked up and discarded at aid stations.

To be clear, most of our testing up until now has shown certain systems to lower drag when installed properly. These would be the bottles that hang below the extensions (Torhans, Profile FC35, etc.). In fact, we have a boat load of data on this, which is why I was so surprised by the results. I expected the Scott’s system to decrease drag thereby closing the drag gap I knew would be created by the position change. I figured if it closed it enough, it would be worth staying in the higher position and using the bottle. Not so much this time.

The shape of a BTA, a true BTA, doesn’t much matter since it’s really not exposed to the wind. I always find it funny that many of these bottles are aerodynamically shaped. Why? A regular water bottle can be replaced very quickly at an aid station. No refilling before you leave the litter zone; just replace and dump. Which would be faster? Re-filling the bottle or replacing it? To drink from a straw doesn’t require much change in position while grabbing a bottle out of the BTA holder and drinking does. Still, how much time are you giving up re-filling that refillable bottle as you go through an aid station v. quickly grabbing and replacing? It all might be aero neutral in the end, or one might be more aero through the course of a race.

I agree, though, that how you use the bottles, or even the ability to use them so you stay hydrated or get sufficient caloric intake, is an important part of the set up process that can be overlooked. It’s easy to get caught up chasing the lowest CdA. I don’t know of anyone that hasn’t fallen into that trap at some point eschewing practicality.

well. there you go. shows you what i know.

19

Perhaps a bit off topic, but is there any aero penalty for that type of Garmin mount? Maybe I’m seeing it wrong though. From the pictures, it looks like this is the barrel mount with bungees holding on the Garmin.

jake

20

Perhaps a bit off topic, but is there any aero penalty for that type of Garmin mount? Maybe I’m seeing it wrong though. From the pictures, it looks like this is the barrel mount with bungees holding on the Garmin.

what in god’s green earth does this have to do with swimming!! :wink: