Aero value shopping list

Triathlon Forum
1

In a previous thread, a poster asked about a “aero/cost” guide to help in decisions on which equipment will improve a rider’s aerodynamics and at what cost.

Similar to the “dollar per gram” rule for upgrading (paying no more than $1 per gram of weight savings for upgrades based solely on weight savings), I propose a guide for the consumer based on a “dollar per second” rule.

Now, of course, all of this is up for interepretation, and aero savings are not linear, however I think that there is a value to this, and hope you agree.

So, with your help and research, I believe that we can hammer out the “aero savings” time for various wheels, frames, helmets, aerobars, etc., and post them here. When finished, I will lay them out on www.timetrial.org, in a PDF format.

So, I will take the first swing at this, please correct me if I am wrong:

Base case is a rider wearing a jersey, shorts, road helmet, riding in the drops on a round tube frame and fork with box (Open Pro 32 spoke) wheels over a flat, calm wind, 40k TT course.

LG Prologue TT helmet = $100/30 seconds = $3.33 per second (Cobb)

Syntace bar/C2 clips = $200/90 seconds = $2.22 per second (Martin)

Vision integrated = $300/120 seconds = $2.50 per second (Martin)

Short sleeve skinsuit = $70/29 seconds = $2.41 per second (Rainer Pivot)

Add shoe covers = $30/13 seconds = $2.30 per second (Rainer Pivot)

P3 w/aero fork = $2200/150 seconds = $14.66 per second (Martin)

Javelin Arcole w/aero fork = $1800/150 seconds = $12.00 per second (Martin)

Zipp 999 wheelset = $2100/180 seconds = $11.66 per second (Zipp)

Hope I did not open Pandora’s box, but this seems like it could be fun!

3

I don’t think you can ride both frames and aerobars at the same time ! I make it 8.42 using the best listed. Just shows what bullshit numbers come out of wind tunnels ! I bought a disc wheel and vision tech bars and I haven’t seen any difference although it is hard to measure. I’m putting the old syntace bars back on as the vision techs are a pain in the arse to train with.

5

Interesting angle to consider! What about aero chainrings…any time supposedly saved there? Glasses? Waterbottles? Internally run cables? I have no idea about assigning any of these a time savings, if there is any. Oh, seat-tube-less frames? (You’re welcome Adam from Softride and Tom from Titan Flex!)

6

According to the aero data in front of me, a disc saves about 40 seconds over a 40 kms TT. Hows this for the ultimate bang for the buck:

CH Aero disc cover = $59.95/40 seconds = $1.50 per second

8

Bah.

Do-it-yourself cover: ~$15.00 (including the yogurt you can eat)/40 seconds = ~$.40/second.

Taped-over helmet: ~$.50/30 seconds = ~ $.02/second.

9

If someone has an old stack of “Triathlete” laying around, there was an article in 1995 or 1996 that listed such savings. Everything from light tubes to wheels to aerobars etc. The cheapest savings? A good position on the bike. Its free. It was a great issue. I remember it because it was the first one I bought!

10

According to the aero data in front of me, a disc saves about 40 seconds over a 40 kms TT. Hows this for the ultimate bang for the buck:

CH Aero disc cover = $59.95/40 seconds = $1.50 per second
That right there would be my choice for cheap time (and is the only piece of gear I’m buying next season). We’ve all got aerobars already. A deep front wheel and a disc are the next most important items in line.

11

Do you really think that a taped helmet (or TT helmet) saves you 30 seconds?

12

Wouldn’t it be better to show a part as a wattage savings, rather than a time savings. As you increase the wattage the time savings is going to be different. But if you show that you can save/gain 30 watts, that would be a more accurate portrayal.

13

"Do you really think that a taped helmet (or TT helmet) saves you 30 seconds? "

Yes. According to Cobb. Apparently taping over the holes works about the same as a aero helmet. The best stuff to use is that celephane looking stuff that we use as winter window insulation in northern climates. You tape around the perimeter of the helmet and then blow it on with a hair dryer to cover the holes. Tim it with the scissors and it makes a nice neat job. It’s so barely noticeable that nobody will think you’re a dork!!

I actually noticed a couple of track riders during the Olympics had done this.

14

Apparently taping over the holes works about the same as a aero helmet

I wasn’t doubting that - I was more doubting that either saves that much time.

15

The time savings are most likely not additive.

17

I don’t think the problem is with windtunnels, a windtunnel is a great tool for evaluating aero drag. But extrapolations of time savings need to be taken with a grain of salt.

The standard convention is to estimate time savings based on a totally flat course with no turns. This makes sense in terms of making comparisons, as to do it any other way introduces all kinds of variables, but it means that the savings are overstated in terms of most people’s real-world results. The more time you spend climbing or slowing down for turns, the less the time savings from aerodynamic equipment. I also suspect that the comparative savings for slower riders vs. faster riders change significantly once you introduce a lot of hills and turns into the course, as slower riders spend more time going slowly as a result of these factors than faster riders.

Based on very unscientific personal observation, I experience savings of one third to one-half the commonly quoted savings of aero equipment in my results. But the courses I ride on usually have significant amounts of hills and turns. YMMV.

18

Wouldn’t it be better to show a part as a wattage savings, rather than a time savings. As you increase the wattage the time savings is going to be different. But if you show that you can save/gain 30 watts, that would be a more accurate portrayal.
That would be a tough one, to show wattage, measurements would have to be very precise.

19

Lowering the front end of your new Javelin several centimeters.

Benefit: The biggest listed yet.

Cost: Stretching and maybe an adjustable stem if you don’t already have one.

http://www.timetrial.org/images/jav1.jpg

20

If I go any lower, I will have a negative slope on my back, it is completely flat in that position. According to Jim Martin, that is about as good as it gets.

21

Some of these projected time savings seem a bit off. For a rider going 23 -25mph over 40K on a flat no turn course, I would project closer to the following time savings:

Aero Helmet - 2-3 seconds for taped helmet, 5-7 seconds for standard aero helmet Snell approved, 15 seconds for Troxel Radius, Briko, Rudy, Limar, etc. 20 seconds for Custom Giro Lance - assuming rider is keeping head in best aero positon (Not looking down with point skyward)

Syntace - 45 -60 seconds with Cowhorn and Dia-Compe style levers over drop bar/STI and Syntace

Vision Integrated - With new levers 90- 120 seconds (Can also improve postion significantly)

Skinsuit - about 3 seconds over tight Jersey, 30 seconds over flapping singlet. 15 seconds over tight Jersey for Super US Postal Skinsuit.

Shoe Cover - More like 2 seconds for most shoes with 3 straps and or buckles. Maybe 3-4 seconds for shoe with one large strap and no buckles.

Aero Wheels - Disc rear and Deep dish front. 45-60 seconds seconds over shallow (Zipp 303) aero rim sets

Aero Frame - 10 seconds bike with aero downtube. 20 seconds bike with aero downtube and seatube (No Cutout), 45 seconds Aero frame with good aero tubes, and cutout) 60 seconds plus for All tubes aero, stays aero, internal cable routing, integrated Aero seatpost, One inch headset.

Aero fork - 20 seconds most aero forks. 30 seconds best aero fork.

22

I’m going to shave 2 minutes off my time by buying 4 LG Prologue TT helmets.