Wheel weighs 699 grams bare (Zipp lists it at 718g but mine weighed less). (773 grams for 404 Aluminum so 74 grams saved) Spoke holes 9mm plus for the larger yellow Velo Plugs with a dab of Vittoria Mastik so they won’t come out on a field tire change. Old 404 brake track 22.5mm, new carbon brake track 25.5 and it is angled or curved. Haven’t tried it yet with my brakes but should work OK. (Zero Gravity - Campy brake pad)
To account for the differences in airflow patterns between clincher tires and tubulars, Firecrest employs a complex set of high-radius curves to adjust the width of the rim from 25.5mm at the braking track to 27.5mm at the rim’s widest point. This less tapered version of our proven hybrid-toroidal clincher rim shape particularly improves the aerodynamics of the wheel. With Firecrest and Zipp’s ABLC™ dimples, the 404 Carbon Clincher far exceeds the aero performance of any other clincher wheelset in its class.
At first glance the carbon rim Firecrest sure does not look as aero as my aluminum rim Zipp 404 to me.
The blunt curve in the inside looks beefy and sturdy but not very aero. I am buying Zipp’s claims of aero as I think that for a wider tire, like 22mm, (which will save me a couple of Watts Crr over my 19mm tire) it will be more aero, but I will need some convincing that overall it will be as aero as my 19mm on my aluminum rim 404.
I started by peeling off the labels covering my coveted dimples. 6 grams saved. Then did not use the Zipp rim tape at 16 grams - Velo plugs instead at 2 grams - threfore 14 grams saved. I will use my own homemade flush mount Ti skewers (bolt down) and save several grams over the Zipp quick release skewer at 33 grams.
Tires and tubes on order and to be installed later.
Look at the wheel “backwards.” In other words, look at how aero the wheel looks as compared with your current wheel IN REVERSE. You need to remember that the trailing edge also works as a leading edge at half (sort of) the time. That’s part of what makes the new shape so fast. So as confusing as it may appear at first, it may look more logical when you look at it in “reverse.”
Are you just saying that to make me feel better? …
One of the reasons the Lockheed version of the F-35 got chosen over the Boeing was that it ‘looked more like a fighter plane’ and the Boeing was ugly.
No, I get it. And for me with my equipment - data driven … beauty is as beauty does … form follows function … yada yada yada …
Would be fun to see some wind tunnel comparison data for it though.
I will really appreciate the improved Crr with a larger tire (and rim to match) too. And it will ride smoother (wider tire) although that will be hard to quantify.
Also if it stalls at a greater yaw angle it should be more stable in gusty cross winds which will help me stay in an aero position more and that will be a big plus.
Small touch I like are the aero shaped outer hub bearing cones (or whatever the correct nomenclature is). Nice attention to detail.
glad to hear you decide to replace the campy brake pads with the cork… otherwise I would be expecting the tearful follow-up post later on that your expensive carbon clincher rim has been turned into pencil shavings
Do not take a sip of coffee before your ride…you will gain back all of those grams
Remember to shave your head bald too…I mean, we are worried about weight are we not? Oh, and cut the liner out of your shorts…not only is it extra weight, it holds moisture that only adds to the total weight…
I have done all that and more (well … a USMC haircut - not completely bald) to not leave anything on the table weight wise but where I really get stupid-silly is in the aero end - but that is part of the fun.
Extremism in the pursuit of perfecting bicycle aerodynamics is not a twisted perverted vice but rather a mark of character and intellect. (Apologies to Barry Goldwater’s ghost)
On the other hand, I have a friend I cycle with - he is a bit younger than me - and he has done Paris Brest Paris a couple of times, went to Kona last year and is going again this year - and rides a bike with round tubes - all of them - even the chain stays. Not sure of the material, might even be Reynolds steel tubing. So the aero and weight stuff is a bit silly - but it is fun for me to move toward the max efficiency goal.
If I had the bankroll I’d roll those wheels with R4 Aero Tires every day, I’d hunt down moms on bikes towing their children in bike trailers and crush their dreams with my aero super wheels
.
If I had the bankroll I’d roll those wheels with R4 Aero Tires every day, I’d hunt down moms on bikes towing their children in bike trailers and crush their dreams with my aero super wheels
x2. And I’d build up the rear wheel with a Powertap.
Regarding the Fircrest clincher vs Tubular… Which is tested faster or are the two rims shaped diferently based on the type of tire? In Tom A. Bontrager pic, I can’t imagine the tubular being more aero…
****Disclaimer- I race tubulars. I like them and have glued and ridden hundreds over the last 20 years… I’m not trying to rehash the tubular v. Clincher debate here… But the recent pictures and new rim shape technology is intriguing…
WOW!!! Tom have you field tested these things? Any data to share?
Yeah…but I wasn’t exactly happy with my attempt to “shorten” the laps on the halfpipe venue and incorporate some of Adam Haile’s “Short Track Aero Testing” protocol…apparently my original protocol is less “noisy”…so the results are exactly conclusive. I’ll probably redo the testing with my original protocol at some point.
Anyway, I ran this 404 CC prototype (from Rappstar - and they’re apparently NOT the final Firecrest shape) with the R4 Aero tire (from AFM) against my narrow Jet90 clincher(w/Bonty AW19TT) and Jordan’s 1080 clincher (also w/Bonty AW19TT)…with the end result being that I wasn’t able to detect any difference between all 3 front wheel setups. That’s not very surprising seeing as how the testing is basically at zero yaw…but it is encouraging for the 404CC w/R4 Aero because it obviously has a larger frontal area.
Regarding the Fircrest clincher vs Tubular… Which is tested faster or are the two rims shaped diferently based on the type of tire? In Tom A. Bontrager pic, I can’t imagine the tubular being more aero…
****Disclaimer- I race tubulars. I like them and have glued and ridden hundreds over the last 20 years… I’m not trying to rehash the tubular v. Clincher debate here… But the recent pictures and new rim shape technology is intriguing…
Basically, the same shape. There will be the tiny differences that are required to make a tubular wheel or a clincher wheel, but nothing substantive. The wheels test the same with “equivalent” tires, but since there’s no tubular “equivalent” to a tire like the R4, I don’t know what the results of such a test would be. I.e., no ones yet done a test to see which is fastest given the choice of any tire. I.e., I don’t know if the absolute fastest that a clincher setup could be is faster than the absolute fastest that a tubular set-up could be, or vice versa.
