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Discussion Starter · #1 ·
I'm trying to put some pieces together real-world aero wheel savings:

I've seen the charts on Hed's website listing some drag specs on their wheels, and read in High Performance Cycling (Jeukendrup et al.) that switching from 32-spoke open-pro style wheels to full-aero wheels can save ~1 minute in a 40k TT.

The difference between the aero wheels and the Open Pros seems impressive. How much of that gap to semi-aero, low-spoke count wheels save?

I ask because I've got several stage races with time trials in my near future. The time trials are short, however, ~20km. I currently have 2005 Campag Zondas, 30mm rims with 16 / 21 spokes.

Is it worth the effort to borrow some Zipp 303's from a friend? Will the 44m rim make any kind of difference?
 

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If the Zondas also have aero spokes, you will already be most of the way there. Crosswinds will favor the 303s a bit more. The best clinchers have lower rolling resistance than tubulars, so consider that as well.

Unless you are seriously in the hunt for the win, I'd advise just using what you have.
 

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Repeating, repeating, repeating

You've seen it here many times before: the best aero wheels are good for a 0.4 mph increase at 25 mph compared to 32 spoke box section wheels. That is where the one minute in a 40K TT comes from. With that, you get increased sensitivity to crosswinds. The Zondas have probably given you half of that, so going to the best wheels would maybe give you another 15 seconds in a 20K TT.
 

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Discussion Starter · #4 ·
I know it's repeating, Kerry, but I appreciate the actual information. I've seen the "minute for best aero wheels" plenty of times, you're right.

What I didn't know was if the semi-aero wheels, like my Zondas, were worth 10% or 50% of the "best" aero benefits.

So, considering a 303 isn't the "best" wheel, let's say I'll get between 5-10 seconds.

In my last stage race, 10th through 5th on GC were separated by 12 seconds. It's worth knowing. I don't think I'd pay retail for Zipps, or anywhere close to it, but still.
 

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Argentius said:
What I didn't know was if the semi-aero wheels, like my Zondas, were worth 10% or 50% of the "best" aero benefits.
There are no easy answers in aero...

I would say more than 50%... but I also think there is more than 1 minute difference between say a 32 round spoke box rim wheelset and a Zipp 808s.

Check here for some old data:
http://forums.roadbikereview.com/showthread.php?p=550582#poststop

Note how well the Alex wheel does... but also note that the 303 is an older model and the new ones are better.

I'll post some other data that is no longer available online when I get more time...
 

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Argentius said:
Is it worth the effort to borrow some Zipp 303's from a friend? Will the 44m rim make any kind of difference?
Don't discount the placebo effect. If you feel fast you're probably going to be faster. I'd race the more aero wheels on that basis alone. Breaking out the go fast gear means you are "showing up" to the race.
 
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