You're correct that the 285v4 is the version of the 303 that was out previously, which has been replaced as of the Eurobike introduction of the 303 Firecrest in tubular and clincher. I'm not sure what the hold-up is in terms of changing rim designation in the catalog and website. These have been shipping for both clincher and tubular since early September.

Taking advantage of an out-of-date image still on our site, you can see the previous tubular rim here: http://www.zipp.com/wheels/detail.php?ID=37

Note the decidedly smaller radius at the spoke bed relative to this image showing the 303 Firecrest: http://zipp.com/wheels/303-firecrest-reg--tubular/
Both the 303 carbon clincher and tubular are accessible from the "Wheels->Firecrest" pull-down at the top of our site.

Brief mention of 303 Firecrest in the technology page: http://www.zipp.com/technologies/aerody ... ecrest.php

I'm not sure which technology page you're referring to but if you can link me to it I'll have it amended for clarity. Sorry for the confusion.

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Zippy engineer

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www.ergottwheels.com

Thanks Eric. I'll let our web guy know when I get back from lunch.

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Zippy engineer

While you're at it, please put up an aerodynamic graph for the 303's that is to the same scale and parameters as the graphs you have for the other wheels. And in addition, it sure would be nice to see one graph on your page that has all of the wheels, using similar conditions so that we wouldn't have to do that ourselves and assume the conditions. As you can see from the first part of this thread, I believe that people are being misled somewhat by the graph you do have for the 303. It's not the same scale or setup.

To be specific, here's the 404 drag chart:



Here's the 808 drag chart:


And then here's the 303 drag chart:

Forgive me if I haven't seen it.
But why is it that Hed will show data across the spectrum on their wheels versus Zipp?
Yet I have never seen Zipp do this....curious.

From what I have been able to observe...I could be wrong.
Hed has better average aero data across their range of products versus Zipp.
Their quality is very comparable.
Zipp is outrageously priced.

Am I missing something? I would really like to understand why someone would spend more for Zipp.

Thanks

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http://www.bobkestrut.com/images/1983worlds.jpg

Question for the guru's here - If thread hijack, my apologies, and disregard the post

I have a pair of Enve .45 tubs laced to alchemy orc/elf 20/24.

No complaints with the wheels other than the amount of money I invested for the little I use them.

How much of a compromise, if any, would going to the 303's clinchers represent in terms of performance? I understand the weight penalty, but also understand that the Enve's aren't particularly Aero, even though they are 45s.

If you're talking about the data on HED's site, it's comically outdated. They also take drastically different approaches on their clincher wheels (Jet's being a non-structural carbon fairing over an aluminum rim vs. Firecrest being carbon clinchers) so there's definitely a difference for the price between the two. If you look at their tubular wheels (Stingers vs. Zipp's line) the price difference is a hundred bucks.

I think the most recent HED vs. Zipp graphs are actually on Enve's site for their 6.7 wheels (edit: not the 303 Firecrest as labeled) and Bontrager's for their new Aeolus line

Of course everyone's own wheels show up faster and better, so take it with a grain of salt, but you're looking at very fast wheels no matter the brand.

Sorry the charts are not to your liking. The reason for the different scaling is to better differentiate the wheels of a similar class; if we used the same scaling for plots from 202-808 it would artificially compress data sets of similar wheels. The last chart is pulled directly from my test database; it was never designed to be visually appealing so it's funny to see it out there. In any case, I'll put in your request but as the test engineer, I don't have much pull on the web side of things.

rainbowstripes, are you referring to the older Hed data generated using a tire that voided their warranty? Although they've altered their warranty recommendation, they still recommend at least 24mm tires for larger riders. This significantly affects the data.
Also, some of the data they've provided purporting to show Zipp products on Slowtwitch in the past was sufficiently out of the norm that they instituted a new policy at that site governing the posting of data. This aligned with Zipp data that had been on the Hed site in the past but I haven't checked recently and don't know the source of the data you reference so I'll end the speculation here. We've provided data for them in the past and certainly will again (witness the H3 data above as just one example).

They've made design decisions that somewhat dictate tire choice; we've made our design decisions on what we feel will have a wider benefit over a variety of tire widths and models. That's the beauty of open-ended engineering problems and simultaneously the pain of the compromise that is engineering.

As to the "outrageous" price, you're comparing one wheelset consisting of a Chinese-made rim on a Taiwanese hub and a second wheelset entirely made in the US outside of Swiss bearings and Belgian spokes. Seems to me that cost of goods, much less labor, would dictate a significantly larger price difference than $100, so I have to admit I'm a bit confused by that comment.

BeeSeeBee, you may want to check the date when the Enve data was released. It predates us finalizing the shape of either clincher or tubular 303 Firecrest by several months, so I'd certainly be curious how they got data for a wheel that didn't yet exist.
Perhaps it's an honest typo on their part, but I'm surprised none of the media outlets didn't catch it when they reprinted those charts, seeing as at that point it seemed all the media wanted to know of us was when a 303 Firecrest could be expected.

Also, on-bike data is a very tricky thing. One thing to remember is that many of the popular frame designs stall between 10 and 18 degrees (some of the newer designs push this out more towards the higher end of that range). Once that occurs it can have a significant effect on the overall data, so as with any data released (including ours), it would be really great to have some error bars and know a bit more about the quantities of runs that were performed.

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Zippy engineer

I can understand your issue with scaling, and the existing graphs serve the purpose you have, (except for the 303 drag curve). However, I'm sure you've seen the discussion in many forums on comparisons across the zipp range. Not sure about the claim that the scaling would artificially compress the data sets. If they are all on the same scale, there won't be any compression, its just that it will be far more obvious that the lower tier wheels are dramatically less aerodynamic than the upper range. That's why many recommend the 808 FC's. They are just so much better aerodynamically. I just think a plot with all of them on one graph, in addition to the graphs you already have, would help inform the consumer. That may not be what you want from a marketing point of view, but of course that's why the engineers always argue with the marketing people!

rainbowstripes, are you referring to the older Hed data generated using a tire that voided their warranty? Although they've altered their warranty recommendation, they still recommend at least 24mm tires for larger riders. This significantly affects the data.
Also, some of the data they've provided purporting to show Zipp products on Slowtwitch in the past was sufficiently out of the norm that they instituted a new policy at that site governing the posting of data. This aligned with Zipp data that had been on the Hed site in the past but I haven't checked recently and don't know the source of the data you reference so I'll end the speculation here. We've provided data for them in the past and certainly will again (witness the H3 data above as just one example).

So this data is no good?
It clearly shows the stinger 4 superior to the 404 tub or stinger 9 superior to 808 tub

http://hedcycling.com/aerodynamics.asp

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http://www.bobkestrut.com/images/1983worlds.jpg

Rainbowstripes, that's the data that is really outdated (first appeared on their site in early 2009 I believe). It predates their three(?) changes to the Stinger line and at least one to the Jet line.




You're right. I knew their original tests didn't label the 303 as Firecrest, but now on the site (with the same graphs) it's labeled as 303 Firecrest

goodboyr, thanks for the understanding. The point I was trying to make was that if you have data for a range of wheels spread over a range of roughly 100 grams (from ~80-180 on the 404 plot, for example). When you extend the scaling another 100+ grams for a 202 plot that would include wheels like the Hyperon and down to around zero for discs, the differences in 303 class, 404 class, etc. become a bit less apparent (plus something showing all our wheels plus competitive product would be very crowded). I hadn't seen the discussion on any other forums as I'm trying not to cheat on WW and busy re-vamping my personal website, but I'll talk to the web guy and our marketing guy and see what I can do. No promises, though.

rainbowstripes, I'm glad to see you embracing a more analytic approach to aerodynamic evaluation. I'm sure the Hed data is real. I'm also sure that the Stinger 4 and 404 were not tested at the same time, given that the 404 (now two-generations outdated) was on that site for some time prior to the introduction of the Stinger 4 (as BeeSeeBee noted, that info has been on that site for some time now). Given that anyone with a significant amount of time spent in the wind tunnel will tell you that for making a valid comparison it's critical that the wheels be tested in the same tunnel, same atmospheric conditions (yes, the correction is trivial but certain tunnels can exhibit a shift as the tunnel warms up throughout the day, regardless of this correction), and using the same tire model/width, much less exactly the same tire, this comparison seems to have several significant flaws.

Aside from that, I've never seen data for a 404 suggesting that it stalls at 5 degrees, even with 25mm and 27mm tires. I'd suggest checking out some of the Tour Magazine or other independent data if you'd like to see more comparisons with various manufacturers. One thing I will note is that in one of the recent tests the 404 that was tested was the magazine's long-term test wheel and so the wind tunnel testing was done with the same worn tire that was on it, as it was the same model used on the other wheels. As the data we saw wasn't quite what we're used to, we inquired about it and found the tire had a somewhat significant flat spot on it due to the mileage on it prior to the test. That said, as I recall it was still superior to several other manufacturers' deeper wheels.

BeeSeeBee, thanks for the correction. I couldn't quite reconcile why no one questioned the 303 Firecrest data given the timing but now it makes sense. Seems like a bit less of an honest mistake to me, though.

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Zippy engineer

I'd like to see at least Zipps wheels on a common graph. I know that visually it makes some wheels look similar due to scaling but, in your manual it states the 303 is one watt slower than the 404. That suggests to me that the 404 really isn't needed, given the cost / weight/ handling differences. I know 1 watt is an over simplification, but without the graph thats what we are left with.

Exactly the discussion we had on slowtwitch, and exactly the point of my original question. Thanks, styrrell for stating it in a much clearer way!

http://forum.slowtwitch.com/gforum.cgi?do=post_view_flat;post=3654910

Hi Waldo,

I am also interested in a more detailed graph of the 303 FC vs the 404 FC. And is the 303FC Carbon Clincher as fast as the 303FC tubular?

The 303FC tubular is designed for wider tyres than 404FC tubular and 808FC tubular. But what about the 303 carbon clincher compared to the 404 carbon clincher and 808 carbon clincher? The brake track of the 303CC (Carbon Clincher) is narrower than the 404CC and 808CC according to zipp.com

Brake Track Top for the 303CC is 23.34mm
Brake Track Top for the 404CC is 24.89mm
Brake Track Top for the 808CC is 24.38mm

It seems (based on the Brake Track Top) that the designs for the optimum tyre for the Firecrest Carbon Clincher differ from the Firecrest Tubular.

Brake Track Top for the 303 firecrest tubular is 25.34mm
Brake Track Top for the 404 firecrest tubular is 21,93mm
Brake Track Top for the 808 firecrest tubular is 25.94mm

Based on the Brake Track Top for the firecrest tubulars I can understand that the 404 rim is designed for tyres <= 23mm and the 303 rim for >= 23mm. But what about the 808 firecrest tubular and the three firecrest carbon clinchers?

Where the 404 firecrest tubular has the narrowest brake track top, the 404CC has the widest.

In other words what's the difference between a 303CC and a 404CC with 1) 23mm tyres and with 2) 25mm tyres? Or is that the same as with the tubulars? Based on the brake track top difference between the CC and tubular version I guess it is different?