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PostPosted: Sun Mar 12, 2006 8:21 pm 
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Okay, so this is not technically a weight discussion. However, I ask it here because you guys know your shit. So, I need a pair of race wheels, have about $300 bucks to spend, and race crits and road races in college. By race wheels, I don't mean amazing wheels, I just mean something other than the shimano r540s weighing almost 2000 grams which I have beaten the shit out of. I am decidiing between Easton Vistas (1797g) and 2004 Mavic Ksyrium sls (which my buddy will sell me for about $300.) In terms of weight, the ksyriums would obviously be the joice. BUT, the only race I do where weight really is an issue is the MW hillclimb. All other races are mostly flat, so aero is the issue. Eastons have a 30mm rim and regular spokes, mavics have like a 25 mm rim and bladed spokes. Which would be the better buy do you guys think, in terms of aero benefit? It's my simple understanding that bigger rims are more aero. Educate me, please. Thanks a bunch.


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PostPosted: Sun Mar 12, 2006 11:09 pm 
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There arn't many wheels in the market less aero than K's. They're on par with 32 spoke Open Pros.

The K is probably very stiff and durable but the aero rim will be faster.


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Posted: Sun Mar 12, 2006 11:09 pm 


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PostPosted: Sun Mar 12, 2006 11:29 pm 
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I don't have any experience with the K's but the Vistas came stock on my Cervelo R2.5
Before I changed them to some light clinchers I weighed them as
790 front 960 rear

I must say that while I rode them I was very surprised at how fast they were.
I guess the 30mm does make a diff on the flats & rolling flats

Also you can get them very very cheap.
I have seen them for 150 new on Ebay I think.

I had Vittoria Diamante Pro lights on them.

Overall if not looking for light climbing wheels I was very happy with them.
Also made me realize the aero benefit is quite real.

Good Luck.


Last edited by flying on Mon Mar 13, 2006 7:06 am, edited 1 time in total.

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PostPosted: Mon Mar 13, 2006 12:15 am 
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According to Zipp wind tunnel measurements, a standard set of 32 spoke wheels will require 57 watts to spin at 30 MPH and zero degree wind angle. The required wattage increases to about 66 watts at a 30 degree wind angle.

For reference Zipp 404s require about 39 watts at zero degrees wind angle and about 43 watts at 30 degrees wind angle.

Mavic Kysriums require about 46 watts at zero degrees wind angle and about 52 watts at 30 degrees wind angle. Across the test range, Mavic Kysriums consistently require about 1 more watt than Zipp 303s, which have 30 mm rims and are probably very close in aerodynamics to Easton Vistas.

Mavic Kysriums are not that bad aerodynamically, about the same as Easton Vistas. You should make your decision based upon other factors.

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PostPosted: Mon Mar 13, 2006 1:12 am 
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Ksyriums are on par with 28 CX-Ray build and a DT rim. It's pretty good for a low profile wheel and general riding.


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PostPosted: Mon Mar 13, 2006 5:58 am 
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sd


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PostPosted: Mon Mar 13, 2006 6:18 am 
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I would go for the K's, not convinced that 30 mm rims can offer a tangible aero benefit. Plus, the K's are proven and bulletproof.


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PostPosted: Mon Mar 13, 2006 2:11 pm 
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The data Bruiser posted (from Tour) is similar to that from Zipp and confirms what both Divve and I mentioned above.

What is interesting about this data is how good an "all around" wheel the Shimano Dura Ace appears.

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PostPosted: Mon Mar 13, 2006 2:31 pm 
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I use Mavic Ksyrium 2001 as my daily wheels.
Broke two spokes in 4,5 years (rear wheel at the drive train side).

And now I have to replace my rear rim. I am tearing the nipples out of the rim…. :) Hehehe ......That happens at a weight of over 90kg and lots of watts output on a pair of wheels that weigh 1595grams…...

I guess that the Vista's would not have hold that long.
But I don’t know since I never owned a set of Vista wheels.

Considering the Aerodynamics both are not great and a 30mm rim does not ad that much aerodynamics that you should take it in consideration.

Aerodynamics do start counting about 40mm or 45mm high rims.
At a rim height under 40mm forget about the aero effect.

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PostPosted: Mon Mar 13, 2006 6:41 pm 
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I'm guessing you guys havn't riden to a bike shop holding a spare wheel in your hand and feeling the wind movements.

30mm makes a substantial difference.


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PostPosted: Mon Mar 13, 2006 7:51 pm 
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Bruiser,

You compare two total different situations. That's wrong.

A rotating wheel in a bike moving forward is something completely different. Then holding a wheel that is not rotating……….

It is proven numerous times that a rim under 40 mm in height does nothing substantial from the aerodynamic view. Of course there are advantages in stiffness etc.

From the aerodynamic view both wheels Livestron1786 suggested are a waste of money.

BTW Bruiser the K’s are not that stiff at al! But stiff enough. The wheels Divve mentions are probaly much stiffer even more if you use a 30mm high rim and 28 spokes (and cheaper too).

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My bike is Italian so it is Nervosa and of course has Anorexia I like them thin!
GIOS "New" Carbon Ultra 2006 Campa Record+Special parts.
GIOS "New" A90 2008 Campa Record+Special parts. My winter and vacation bike.


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PostPosted: Tue Mar 14, 2006 3:34 am 
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Perhaps I am wrong but I have ridden almost 20 years & when I had those 30mm Vistas on it was quite a bit faster.....noticeably

It is not like I wanted to like these as I knew they were history as soon as I had some light wheels built.
But after changing to the light wheels of course I love the weight & the climbing etc.
But they are nowhere near as fast on the flats.

So IMHO the 30mm made a diff for me.
Your mileage may vary ;)


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PostPosted: Tue Mar 14, 2006 3:37 am 
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Guys, you miss the forest for the trees. All data indicates that there is a significant advantage of lower spoke count and a deeper rim depth even 25-30 mm over conventional 32 spoke wheels. Bladed spokes help with a 0 degree wind angle but at cost when the wind is oblique, hence the Kysriums poorer performance in this direction. Obviously, there is additional aerodynamic advantage to deep rims and the rim design can minimize crosswinds by creating leeward lift, the HED3 being the best example.

Unfortunately, neither test (Zipp, Tour) included the Vista, but IMHO the Vista wheelset would behave similarly to the Zipp 303, except perhaps in a crosswind where I would expect them to fair a bit worse, although no worse than the Kysriums.

I stand by my original assessment: from an aerodynamic perspective neither wheelset is particularly bad or particularly good, but clearly better than any conventional 32 spoke rim and most likely Kysriums and Vistas perform similarly with any difference insignificant. As to which wheelset is the correct one for livestrong1786, he should make his decision based upon some criteria other than aerodynamics.

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PostPosted: Tue Mar 14, 2006 4:01 am 
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John979 wrote:
Guys, you miss the forest for the trees. All data indicates that there is a significant advantage of lower spoke count and a deeper rim depth even 25-30 mm over conventional 32 spoke wheels. .


I forgot all about spoke count.
The Vista's are 20F & 24R
Maybe that helped too?


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PostPosted: Tue Mar 14, 2006 4:08 am 
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Ksyriums are 18 front, 20 rear, so that can't be it.


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Posted: Tue Mar 14, 2006 4:08 am 


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