# understanding aero wheels and williams cycling



## seanymph (Dec 21, 2009)

ok guys, here's my questions...

1.) - want to learn more about aero wheels, difference between 38mm and 58mm carbon wheels. 

i am about 145lbs, avg about 18-19mph on 25-30 mile rides. on the group rides, i can hang with the guys that are around 21mph avg for the same 25-30 mile rides. fastest i ever rode a sprint triathlon was 20.3 mph avg for 16 miles. even though this is my 3rd season of riding, this is my first season of serious riding. previous years i could barely average 16 mph avg.

2.) - was wondering if you guys think the 38mm will be any more beneficial? or i have to get the 58mm?! as much as i would love to have both sets, kids and a wife that doesn't make that much money, it's just not in the budget. also would like to upgrade from 105 to ultegra! 

i pretty much have my mind set on williams 38mm carbon clinchers. it seems be a good all around starter set. 

3.) - does anyone have any experience with williams carbon wheels?

thanks for reading and any help!
sonnyd.
pa


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## rruff (Feb 28, 2006)

Seriously... if money is tight, why do you need new wheels at all? What are you riding now? 

The speed increase will be quite small (~0.1mph) unless your current wheels are aero bricks.


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## seanymph (Dec 21, 2009)

money may be tight, but it doesn't mean i dont have money saved up. i am riding mavic aksium race wheels. over 1800 grams for the wheelset. 

i am more serious about my riding, i'm getting stronger, and everything i read says wheels make a difference. the more duathlong, triathlons i do, the more reason for me to upgrade. 

also, from what i've been reading people seem to gain more than .1mph. 

sonnyd.


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## Cni2i (Jun 28, 2010)

Here's an interesting article in the triathlete magazine that may help shed some light for you:


Rick Denny 
Triathlete magazine

*In the world of car racing, there's a saying: Horsepower sells engines; torque wins races.
Don't worry, I'm not going to trail off on a discussion about horsepower and torque. I only bring them up to make this point: Even highly experienced practitioners don't always understand the importance of different characteristics.

In our world, we face the same confusion. Look through some recent ads in bicycle magazines and you'll notice two recurring themes: They're getting lighter and/or more aerodynamic. Which is more important? Let's do some comparisons.

All the calculations presented here came from Tom Compton's superb Web site called Analytic Cycling (Analytic Cycling, Interactive Methods for Estimating Cycling Performance Parameters. Tom Compton). Analytic Cycling performs the computations and also presents the equations.

It is accepted lore that lighter bikes are better bikes, and that reducing weight on wheels has the best effect of all because wheels rotate. I've heard otherwise level-headed folks claim weight on a wheel's rim counts for six times the weight elsewhere on the bike.

Let's send that familiar bovine to its long rest before doing anything else:

Weight on a wheel affects the wheel's rotational moment of inertia. The moment of inertia is a measure of how the weight is distributed on the wheel. The common wisdom is rotational weight counts twice that of non-rotational weight. That's because to accelerate a bike, you have to pick up translational momentum, which is what you gain moving down the road, and you also have to pick up angular momentum, which is what you gain spinning a wheel.

The rotating-weight penalty only affects acceleration, and we really don't have to worry about acceleration very much. The effect of a bike's weight during acceleration is small, and the effect of a wheel's weight is very small.

Prove this to yourself: Run up a flight of stairs. Then run up a flight of stairs carrying a wheel. Finally, run up a flight of stairs carrying a spinning wheel. You get the idea: The weight of the wheel, spinning or not, has very little effect compared to what it takes to accelerate your body.

The other and more important reason the effects of rotation matter little is because we don't accelerate much. If you are doing kilos on a velodrome, then worry about it. Maybe. But in the typical 40K bike leg, we accelerate exactly once, with an additional partial acceleration at the turnaround. You can't even measure the effects.

If you are going up a hill, weight counts. But at a constant speed (uphill or not), weight on a wheel counts exactly like weight on the bike, or weight on your body.

If that extra weight on the rim serves to improve our aerodynamic efficiency, then it's worth it.

Let's do a comparison: Mr. Lightwheels weighs 165 pounds, and rides a bike weighing 17.6 pounds. His twin brother, Aero, is exactly the same. Both can maintain 250 watts of power output in a 40K bike leg, and both face identical wind drag, except for their wheels.

Mr. Lightwheels has conventional wheels lightweight box-section rims with 32 round spokes. Aero has something like Tri-Spokes. (Pick your choice of aerodynamically optimized wheel; I'm using typical numbers.) Standard wheels aren't much lighter, if at all, than aero wheels, but just for fun let's say the conventional wheels are ultralights weighing 200 grams less per wheel.

In a flat 40K time trial, who will win the rider who is lighter, or the rider who is more aero? The answer is the rider with aero wheels will finish more than 28 seconds ahead of his lighter brother.

This includes the effects of the startup acceleration. Even if the bike leg goes steadily up a 3 percent grade, the rider with more aero wheels will win. Only when the grade exceeds 3.7 percent does the bike with lighter wheels have the advantage. And that's 3.7 percent over the whole race, not just the uphill half of a rolling course.

Other analyses have shown aerodynamically efficient wheels are always better, even in bike racing events like criteriums, with the exception of hill-climb events. Even when they weigh more, they are better.

In a flat 40K time trial, the aero wheels would have to weigh many pounds more before their weight soaked up their aero advantage.

That takes care of the wheels, but what about weight elsewhere?
*


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## Mike T. (Feb 3, 2004)

I have two sets of road wheels - with 24mm and 50mm deep rims. I alternate frequently between the two sets and I keep average speed data for all my rides. There is a normal fluctuation within my 17-18-19mph ride averages and the performances of both those wheelsets are within those fluctuating averages.

Edit - on re-reading that, what I should have said is "The average speeds when using the 50mm deep wheels are within the variance of the average speeds of the 24mm deep wheels" or something like that. You get the idea.

Of course if my speeds were much higher (as they were when I was much younger) the aero advantage might be greater. But for me, maybe the shallower and lighter wheelset (at 1410g) might cancel out the aero advantage of the heavier wheels (1597g).

Buy fancy wheels if you like but buy them for the right reasons otherwise you might be disappointed.


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## Lectron (May 29, 2005)

Cni2i said:


> Here's an interesting article in the triathlete magazine that may help shed some light for you:
> 
> 
> Rick Denny
> ...


Only problem is...

The lighter rider is likely to be more aero, but. The bigger guy is likely to be stronger
So...The most aero rider does not win..The better one does!

Ever seen Andy Scleck do an awesome TT? Or Marco Pantani?

They can both be more aero than many of the TT animals Meaning (!)
The bike represents a higher % of their total aerodynamic, meaning they 
even benefit more than the bigger guy having an aero set.

And...Why always this comparisation with a box section wheel with 32x2mm straight gauge spokes?

There are in fact many sub 1250g sets out there that performs good aerodynamic


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## rruff (Feb 28, 2006)

seanymph said:


> also, from what i've been reading people seem to gain more than .1mph.


If you've been around the bike business for long... the placebo effect is truly amazing. 

The Aksium has bladed spokes and 20 front and rear, 24mm rim. The Williams 38 has round spokes, and 20f, 24r, 38mm rim. The Williams wins in the rim depth, but loses in the spoke shape and #.

This is 4 years old now but it still serves the purpose. Tests by Tour Magazine over a period of years, front wheels with <22 aero steel spokes, 0-15 degree yaw, converted to CdA for two wheelsets. 










Nominally you might expect ~.004 m^2 difference in CdA between a wheelset with 24mm rims vs one with 38mm rims... all else being equal. Even then the error bars would have enough overlap such that the 24mm set *could* be better due to rim shape and width or hub design. In this particular case the Williams wheels having round spokes and more spokes will work against the aero benefit. 

So... let's take a WAG and say the Williams has a .002 aero benefit. How does this translate to speed? Your total drag on the TT bike is probably ~.25 m^2, so the Williams wheels would lower your drag by 0.8%. Since the speed ratio on a flat road is proportional to the power ratio to ~^.38, this results in a 0.3% speed improvement. 

So if you are doing 21.000 mph in a race with your old wheels, then you would go 21.063 mph with the new ones. 

Even if you got the fastest wheels available, the speed increase would only be ~5x this great or 0.3 mph.


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## Mike T. (Feb 3, 2004)

Lectron said:


> Ever seen Andy Scleck do an awesome TT?


No but Contadore does and Leipheimer and Zabriskie and..........
Contadore beat Cancellara in a TT a while back too.


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## Lectron (May 29, 2005)

Mike T. said:


> No but Contadore does and Leipheimer and Zabriskie and..........
> Contadore beat Cancellara in a TT a while back too.


Yeah...It's all in the pudding... Or steak?


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## Cni2i (Jun 28, 2010)

rruff said:


> If you've been around the bike business for long... the placebo effect is truly amazing.
> 
> The Aksium has bladed spokes and 20 front and rear, 24mm rim. The Williams 38 has round spokes, and 20f, 24r, 38mm rim. The Williams wins in the rim depth, but loses in the spoke shape and #.
> 
> ...


NIce find and summary.


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## stevesbike (Jun 3, 2002)

following up on rruff's comments, there's a study looking at a variety of wheels. The askium wheels are included. They do pretty badly but it's worth noting that the difference between the best and worst wheels is about 7 watts at 50km/hr. There are better performing wheels, but they are deep (like 80mm) so not general purpose wheels. As he mentions, round spokes negate a lot of the benefit of the deep rim (and 38 isn't very deep). One suggestion would be to get something like the Neuvation alloy wheels or even RS80's since the Shimano wheels with low spoke count perform as well as deeper rim wheels. The Neuvations will give you enough money to upgrade your components for the price of the carbon clinchers. I'd also seriously consider the terrain you ride on wrt carbon clinchers. If you ride serious descents, I'd strongly advise against carbon clinchers. In my opinion, they are dangerous in those conditions and even if you don't have a crash, they can delaminate and get ruined. 

Great wheel test 2008 – Part 1 – Aerodynamics | Roues Artisanales

acoording to studies on that site, rolling resistance differences among tires is greater than drag among wheels.


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## Marc (Jan 23, 2005)

stevesbike said:


> following up on rruff's comments, there's a study looking at a variety of wheels. The askium wheels are included. They do pretty badly but it's worth noting that the difference between the best and worst wheels is about 7 watts at 50km/hr. There are better performing wheels, but they are deep (like 80mm) so not general purpose wheels. As he mentions, round spokes negate a lot of the benefit of the deep rim (and 38 isn't very deep). One suggestion would be to get something like the Neuvation alloy wheels or even RS80's since the Shimano wheels with low spoke count perform as well as deeper rim wheels. The Neuvations will give you enough money to upgrade your components for the price of the carbon clinchers. I'd also seriously consider the terrain you ride on wrt carbon clinchers. If you ride serious descents, I'd strongly advise against carbon clinchers. In my opinion, they are dangerous in those conditions and even if you don't have a crash, they can delaminate and get ruined.
> 
> Great wheel test 2008 – Part 1 – Aerodynamics | Roues Artisanales


One thing I seldom see mentioned with bladed spokes: do these guys go through and make sure there's no wound up spokes? Or test with woundup bladed spokes and without? I never see mention of this in these tests...which is funny considering how seldom bladed spokes are not woundup somewhat in (consumer) wheels.

I could easily see traditional round spokes besting the all too common wound-up bladed spokes that happen on folks' hoops.


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## opollo creed (Jul 22, 2011)

aero wheels or not, it really is the legs that matter!


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## Lectron (May 29, 2005)

rruff said:


> If you've been around the bike business for long... the placebo effect is truly amazing.
> 
> 
> Nominally you might expect ~.004 m^2 difference in CdA between a wheelset with 24mm rims vs one with 38mm rims... all else being equal. Even then the error bars would have enough overlap such that the 24mm set *could* be better due to rim shape and width or hub design. In this particular case the Williams wheels having round spokes and more spokes will work against the aero benefit.
> ...


Good example there is Shimanos 28mm compared to many (good) 50mm having same
aerodynamic. And that not only frontal, but an average of several angles.

One matter that kinda bugs me is that people, not so much here, tends to recommend
a harsh, cheap 50mm(+) over a good versatile low/medium profile due to aerodynamics.
And very often non existing ones....

Take one of the really better ones, 80mm, and compare it to the Shimano @ 40km/h
instead of 50km/h. The savings are about 5.6W. And 40km/h is still fast among 
most riders in here. @ OPs speed ~3W. 3W diff from a medium profile and one
of the really best aero wheels out there

Just proves that spokes matters, and I'm adding a wind-tunnel plot to that @ 30*mp/h*


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## TomH (Oct 6, 2008)

Most people talk about wheel aerodynamics on flats.. but what about high speed descending? Shouldnt the advantage increase as speed increases?I like to be realistic, but It really feels like my 30mm's are faster than my old box rims on fast descents. 

Theres also clip on wheel discs for the rear.


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## masornia925 (Jan 14, 2011)

I own three sets of Williams wheels, one of which is a pair of 38mm carbon clinchers. Whoever doubts the durability/cost of Williams does'nt own a pair; great wheels. This wheel is great, spins fast and is light, but as with all carbon wheel sets stopping can seem icy. If you're looking to go aero i would suggest getting the 58mm as they roll faster at high speeds and are more aero unless u catch cross winds. I believe there was a study somewhere stating that there is no benefits with so-called aero wheels unless they are greater than 38mm...i could be wrong.


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## F45 (Nov 25, 2010)

seanymph said:


> money may be tight, but it doesn't mean i dont have money saved up. i am riding mavic aksium race wheels. over 1800 grams for the wheelset.
> .


If you are not time trialing or a solo breakaway specialist where thousands of dollars are at stake, there is nothing wrong with your Aksiums. If you are going to buy a new set of wheels, you should buy the set that looks coolest on your bike.


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## mtnroadie (Jul 6, 2010)

I was in the same boat as you last year. I had Aksiums and wanted to upgrade.

I looked at all the online wheel builders. I was very interested in the Williams 38 but was unhappy with the response I got from the owner so I took my business elsewhere. 

I ended up going with the Easton EC90sl, I like them a lot. Similar to the Williams but you get Sapim CX ray spokes, which I think is a must if you are going after an aero wheelset. You might have noticed how you get blown around on the Aksiums, its all in the spokes. Believe it or not even with the wider 38mm rims the wind blows right through me now. 

Recently I got a custom built set, white industries hubs, Sapim cx ray spokes and kinlin 27mm rims. They were only $700 w/state tax, can be had online for $650.

I will say this the Eastons are more aero (easier to hold faster speeds and faster overall). The customs roll noticeably better, slightly less aero but slightly lighter. 

Based on my experience with these wheels, I wish I got a 50mm set, I will take aero over minimal weight savings anyday. The Zipp 404 look awesome and can be had super cheap if you know where to look (texas cycle sports . Also I think you can get a sweet custom built set with 50mm rims, White industry hubs and sapim spokes for under $1300, maybe less?

If any deep rim wheelset does not come will quality bladed spoke I would not buy them. Also do your research in the hubs e.g I don’t ride the Eastons in the rain – water contaminates the ceramic bearings super quick, (thankfully Easton has sent out replacement bearings) 

If you’re a lighter guy and don’t do massive descents carbon brake track is ok. I am 145-150lbs and am extremely happy with the braking performance of the Eastons (dry and wet), just keep the pads clean.


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## ergott (Feb 26, 2006)

Rim design is more important than depth. There are rims with toroidal profiles that outperform V-shaped rims with a higher profile.

Even more recent is the trend towards blunt end rims like the Zipp Firecrest, Enve Smart wheels and the Hed Stinger lineup. They are not only more aero in more conditions, they behave better in crosswinds allowing you to hold a steady line better.

I have been riding the Enve Smart 6.7 wheels and they are not only faster (I'll take .3-.5mph faster any day), they don't push you around when the wind shifts or when you have a bus/tractor trailer blow past you. Another note, the braking performance of the Enve rims is better than I've ever used from any other rim maker. Using the Enve pads, they are even better than when I swap in my Hed alloy rims. They are easily an everyday wheel for my road bike.

I see a lot of people buying 50mm rims just because they are 50mm and someone told they they are aero. If you want wheels that are actual faster, you need to pony up to what they big guys like Hed, Zipp and Enve are offering. 

-Eric


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## VanillaGorila (May 14, 2010)

F45 said:


> you should buy the set that looks coolest on your bike.


thats right "looks" mean everything


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## seanymph (Dec 21, 2009)

masornia925, which williams wheels do you have? do you notice you were any faster with your 38's?

mtnroadie, what didn't you like about keith williams response? i talked to him for about a half hour and he was really nice to take to.

ergott, i do like the zipps and enve's but it's just too much at this point, but you're right about ponying up though. i'm just stuck, want wheels bad, but cant afford the real nice wheels. just thought maybe the williams wheels weren't that bad, was hoping they weren't total junk.

sonnyd
pa


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## F45 (Nov 25, 2010)

VanillaGorila said:


> thats right "looks" mean everything


Gotta look good, man.


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## Cni2i (Jun 28, 2010)

masornia925 said:


> I own three sets of Williams wheels, one of which is a pair of 38mm carbon clinchers. Whoever doubts the durability/cost of Williams does'nt own a pair; great wheels. This wheel is great, spins fast and is light, but as with all carbon wheel sets stopping can seem icy. If you're looking to go aero i would suggest getting the 58mm as they roll faster at high speeds and are more aero unless u catch cross winds. *I believe there was a study somewhere stating that there is no benefits with so-called aero wheels unless they are greater than 38mm...i could be wrong.*


Interesting. I would love to read that study. Please post link IF you ever find it. Thanks.


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## masornia925 (Jan 14, 2011)

i have the 19s, 30s, and 38s. I wouldn't say i can notice a measurable diff between the wheels because i use them for diff purposes for the various terrains out here in the bay area (climbing, riding flats,etc) but all wheels seem to spin forever. Cant go wrong with any wheel as long as you have the legs to do what you want because no wheel will make you better single handedly. Best bet is to talk to Keith and he'll help you out with an honest answer/suggestion.

BTW Keith Williams is a super cool guy, interested in the "response" he gave to mtnroadie


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## mtnroadie (Jul 6, 2010)

Yeah I had my heart set on the 38 with all the great reviews, so I sent Keith an email asking some questions about the wheels. All I got back was that he was out of them - that’s it, no attempt to answer any of my questions or provide me with a date when they would be in stock. 

Granted you cant always please every potential customer and things come up, busy day etc. etc. etc., but at the very least make an attempt to answer a customers inquiry and make a sale.

Anyways, a shame really as I was totally sold on the product at the time and probably would have waited another month or so for them to become available again, but I am glad I went with the Eastons instead.


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## seanymph (Dec 21, 2009)

*boyd vs williams*

well, it seems like everyone says the spokes will make a difference, regular versus flat spoke. 

it makes more sense for me to look at boyd's wheels, since they use the cxray spokes. and it appears they use very similar rims also... williams has round spokes and ceramic bearings, boyd has cxrays and no ceramic bearings. 

looks like boyd is a better option. 
sonnyd.
pa


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## ziscwg (Apr 19, 2010)

mtnroadie said:


> I was in the same boat as you last year. I had Aksiums and wanted to upgrade.
> 
> I looked at all the online wheel builders. I was very interested in the Williams 38 but was unhappy with the response I got from the owner so I took my business elsewhere.



Humm, I had a great response from him on all my questions.


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## stevesbike (Jun 3, 2002)

if I were considering carbon clinchers again, a priority would be the technology of the brake track. These range from low-tech (simply a section with no clearcoat), workarounds (lowered brake track), to some formulations that reduce brake heat (e.g., Reynolds, Zipp, Easton). Rim failures during a descent are not fun...


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## ergott (Feb 26, 2006)

stevesbike said:


> if I were considering carbon clinchers again, a priority would be the technology of the brake track. These range from low-tech (simply a section with no clearcoat), workarounds (lowered brake track), to some formulations that reduce brake heat (e.g., Reynolds, Zipp, Easton). Rim failures during a descent are not fun...


Add Enve to that list. They reworked their rims to eliminate the problems with carbon clinchers.

-Eric


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## Lectron (May 29, 2005)

Changing one of those rims as we speak.....(Edge -> ENVE)


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## ergott (Feb 26, 2006)

Lectron said:


> Changing one of those rims as we speak.....(Edge -> ENVE)


Have you worked with/ridden the Smart 6.7s? If you like their regular rims you won't believe how much better they can get.

-Eric


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## Lectron (May 29, 2005)

ergott said:


> Have you worked with/ridden the Smart 6.7s? If you like their regular rims you won't believe how much better they can get.
> 
> -Eric


I might have to get into that....I'm planning next years assortment now.

I really like what I read about them...Right up my alley.

We'll have to see what time brings...I'm kinda in a different continent.
Thou ENVE actually have a distributor in Norway, Norwegian distributors
kinda usually mistakes that role and the actually end sale role.

So..It's either a reasonable deal directly with ENVE or nothing


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## penn_rider (Jul 11, 2009)

ergott said:


> Add Enve to that list. They reworked their rims to eliminate the problems with carbon clinchers.
> 
> -Eric


What did they do to eliminate the problems with other carbon clinchers?


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## ergott (Feb 26, 2006)

Good reading. 

https://docs.google.com/leaf?id=1CL...7x5RtVV9sbDxm0zV00odUiZmkp-KGyDUOZK_&hl=en_US

-Eric


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## penn_rider (Jul 11, 2009)

Way cool.. I do understand their testing tech, but as a builder, do you think that they have designed a wheel that will not exhibit the problems associated with other carbon clinchers? I know that this area will be the next big breakthrough with carbon clinchers and it is nice to see a company take such a stance with their design.


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## ergott (Feb 26, 2006)

Only time will tell if people start posting about problems, but I have a good feeling they got it right. When I spoke to them they were quite confident about it .

-Eric


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## cevita11 (Aug 12, 2011)

good stuff


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## paradigm777 (Jan 12, 2010)

Good write up, thank you.


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## Doug B (Sep 11, 2009)

All of the reading I've been doing about aero wheels indicates that they are faster than a traditional wheel, but only in a laboratory setting. A wheelset that will save me one minute of time on a twenty mile ride isn't worth my money. I think the $1500 would be better spent on getting re-fitted, and a winter gym membership. If the wheels were hands down better and would add 3mph to my average speed, I'd be first in line to buy a set.

I have to admit though... I'd still like a set of 50mm wheels - but only because they look cool. Maybe my buddy will upgrade and sell me his old set cheap.


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## sneakyracer (Dec 1, 2007)

I have proven that better wheels WILL make you go faster. I have a a 2 mile section of road that I time myself on several times a week. It has a nice hill and is well protected from the wind so as not to make it a factor factor. I am consistently 30 seconds faster with the Mavic Cosmic SL wheels than with the Aksiums. I am always within a few seconds of each time. With the Aksiums, around 8 minutes, and 7:30 with the Cosmics. 

The Cosmics roll smoother and are much stiffer under power so they help put the power down. I have a set of Schwalbe Ultremo ZX tires on them also which are Lighter than the Michellin Pro's. But the wheelsets are very close in weight. 

So basically, look at the wheel/tire as a system. Aero performance in the wheels is important but also take into consideration bearing smoothness and wheel stiffness + tire weight, rolling resistance and Tire aero performance (22's are better in that regard).

So do not let anyone tell you otherwise, you can gain minutes, yes MINUTES on a 40km course with the right wheel/tire combo.


Great wheel test 2008 – Part 1 – Aerodynamics | Roues Artisanales


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## Lectron (May 29, 2005)

sneakyracer said:


> I have proven that better wheels WILL make you go faster.


*Better *wheels will. So much is true


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