In the past the 303 was the classics wheelset, and the 404 the do it all race wheel
The new 303 looks very tempting indeed, and is c 100gms lighter than the 404 and according to Zipp’s research only 2 seconds/1 watt slower over a 40km TT
I would be interested to hear from Jordan and anyone else with the inside track from Zipp on how the 303 Firecrest is to be marketed
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If its results are what you say then I’d go with the 303.
Styrrell
I think they will position the 303 to people who don’t do the math on weight vs aero and people who are unduly afraid of handling issues in the wind.
=)
Self conscious roadies who don’t want to too fredly.
I’d take a 100 gram weights savings over saving 1 watt every day. Figure in a pack that 1 aero watt would be effectively non-existent.
Like the Garmin Cervelo team who opted for a roadbike frame in the CO TT? 
Styrrell
I have NOT yet had a chance to talk with Josh and the gang about it yet, but I think that it’s a wheel that really designed with a strong focus on wider tires, perhaps even so much so that narrower tires cannot (or should not) be used.
Theoretically, you could make a number of rim shapes in various depths to pair best with different tires. I believe that the 303 is geared towards wider - much wider - tires. So let’s say the 404 is ideal for tires 23mm and under. Then I’d say the 303 is for tires 23mm and wider.
I haven’t seen the tunnel data, but I’d wager that the 404 with a 21mm is much faster than the 303 with a 21, but that the 303 with a 25 is faster than the 404 with a 25. That’s speculation ONLY (though based off how I know Zipp designs their wheels and also some conversations generally about the topic). The reason the 2sec/1watt over 40km shows them show close is, again just guessing, because it’s based of a 23mm tire, or the width where they overlap.
I’ll double check on this though.
EDIT: the 303 is is faster with a 23mm than with a 21mm tire; I confirmed that. That is really the purpose of the wheel. The 404 is still faster with a 25 vs the 303, though perhaps by even less than with a 23; it was on email without data right there, so I may re-edit that. But basically, the 303 was designed to actually be FASTER with a 23mm tire than with a 21mm. The 404 is designed to be as fast as it can be with a 23mm, but it is still faster with a 21 vs a 23. Hope that helps. Generally what I wrote above is correct though from a “thematic” design standpoint.
Like the Garmin Cervelo team who opted for a roadbike frame in the CO TT?
2 things: First, that was an uphill TT at altitude, thereby aerodynamic drag differences were less of a concern…and secondly, do you not think VdV could have found some aero savings that would have gotten him 0.58 seconds faster, if not 11 seconds?
If they truly set up his R5 with the same position as he had on his TT bike, then he was just ham-stringing himself by not using a P4 IMHO…heck, even just switching to an S5 frame would’ve done the trick, especially considering that these guys have a bike weight limit.
Personally, I think VdV’s bike choice may have cost him the USAPCC title…
In that case, the 303 FC would be an excellent crit rim with 23’s (or even a 25 rear). We all know about the 303 tubies prowess in cyclocross. I’d gladly take “aero” and handling for a couple of watts. Already have some 404s anyway Had to run a Hed Jet 90 once for a crit (just a weekly training one) with a 21 Veloflex on (forgot my front wheel and had my TT wheel in the car). Couldn’t believe how much worse a fast corner was!
Jordan many thanks for that
Zipp are very clever - they make it seem reasonable to justify ‘needing’ three or four of their wheelsets for different events/styles of riding !
You kinda missed there point about frame choice. They do have a limit, BUT, most if not all of the bikes for the TT were significantly over the limit. By choosing the road bike frame they were able to have a weight advantage. They calculated that the weight advantage over the aero advantage was a win.
Its hard to argue. Their rider almost beat a fully aero LL, who is typically a better TT rider and a better climber.
Given the fact that they chose a road frame, they did maximise aero. Aero wheels aero bars etc.
As far as it being a hillclimb wasn’t the ave grade over the whole course about 3%. Sure thats still up hill, but its not the answer you get when asking about aero vs weight. “Well are you planning of doing a TT up L’Alpe Huez” This was a pretty mild grade on ave.
It’ll be interesting to see what happens if the UCI lossens up on the weight limit as rumored.
Styrrell
Since it seems everyone is getting more and more concerned with systems (ie. tires + wheels) can you comment at all on the effectiveness of the Zipp Tangente aero tire as it relates to the new products. Can we expect new optimized tires from Zipp to match these wheels as well?
But what about the 303 carbon clincher? The brake track of the 303CC (Carbon Clincher) is narrower than the 404CC and 808CC:
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.
Were those numbers from Zip or measured. I though Zipp has said that the advantage of the CC is that they can now be shaped exactly the same as the tubular rims.
Styrrell
But what about the 303 carbon clincher? The brake track of the 303CC (Carbon Clincher) is narrower than the 404CC and 808CC:
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.
I’ll check; my guess is that 404 tubular data is a typo. Also not sure what the “aero” width (widest point) of all wheels is. Everyone’s traveling from Eurobike. But there’s no way that the 404 tubular is that much of an outlier.
Following on from Zipp’s useful guide to optimal psi (based on event and rider weight) can I suggest Zipp also identify what is the optimal tyre width for each wheel type
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Following on from Zipp’s useful guide to optimal psi (based on event and rider weight) can I suggest Zipp also identify what is the optimal tyre width for each wheel type
I don’t think there is one “optimal” width. Do you mean the most aerodynamic width? Ideally, what I’d like is a discussion of width vs. aerodynamics, and also why someone might choose a wider tire despite worse aerodynamics. But certainly, at the least, the most aerodynamic choice. And, as a corollary, the penalties for a wider tire. I’m on a con-call this tuesday with the gang, and I will bring that up.
and also why someone might choose a wider tire despite worse aerodynamics. .
As I noted on another thread - comfort. There is a massive difference between something like a 19 and a 23. or a 21 vs. a 25, etc.
For the crappy roads that I ride on in the Chicago area, anything less than a 23 is silly.
If they truly set up his R5 with the same position as he had on his TT bike, then he was just ham-stringing himself by not using a P4 IMHO…heck, even just switching to an S5 frame would’ve done the trick, especially considering that these guys have a bike weight limit.
Here’s what Vaughters wrote on Twitter before the TT. “R5ca w disc&full aero bars was 6.8kgs.P4 was 7.7kgs. Position same. All calculus in, R5ca was 10s slower in 1st8kms, 20s faster in last8kms.”
You might disagree with the results, but they ran what they believed to be their most reliable model before making the decision.
If they truly set up his R5 with the same position as he had on his TT bike, then he was just ham-stringing himself by not using a P4 IMHO…heck, even just switching to an S5 frame would’ve done the trick, especially considering that these guys have a bike weight limit.
Here’s what Vaughters wrote on Twitter before the TT. “R5ca w disc&full aero bars was 6.8kgs.P4 was 7.7kgs. Position same. All calculus in, R5ca was 10s slower in 1st8kms, 20s faster in last8kms.”
You might disagree with the results, but they ran what they believed to be their most reliable model before making the decision.
Thanks for pointing me to that…I hadn’t seen that before.
But, I’m trying to make sense of it. My quick and dirty look at the difference in % grade between the first and second halves of that course and what that weight difference would mean are a bit confusing. Using Ron Ruffs speed vs. power spreadsheet and entering in the appropriate values, if I adjust the CdA so that the P4 setup gains 10s over the 1st half, then the P4 is STILL faster over the second segment (by 1-2s). With a 5 mph tailwind (a tailwind was reported), then the P4 is only 1s slower over the second half, and with a 10 mph tailwind the P4 is only 6s slower over the second half (for a net gain of 4s due to being 10s faster over the 1st half).
The weird thing is, it was only taking a CdA difference of 0.15 - 0.2 m^2 for the P4 setup to gain 10s over the first 8k…I’ve got to believe that the difference between the R5ca and P4 CdAs is greater than that. Heck, I measured that sort of difference between a P3 and a P2K…
Something’s not right with that “10s faster over the 1st half, but 20s slower over the second half” statement…
By my figurin’, VdV could’ve gained somewhere in the range of 5-10s if he’d run the P4 (assuming the weight differences and gain over the 1st half noted above are true).