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Zipp 404 Firecrest Carbon Clinchers: The New “Best”

By Tom Demerly

Zipp 404 Firecrest Race Wheels
Zipp's new 404 Firecrest is a complete re-design at the rim for the venerable, do-everything 404 aerodynamic wheel.

Triathletes love curb appeal. If it looks fast, it is fast. But if the triathlete at-large can’t see a conspicuous change in the appearance of a product, then it must not have changed. And every triathlete knows- old is slow.

That is the challenge Zipp faces marketing the newest version of the Zipp 404 wheel- the wheel that has evolved and changed so much it shouldn’t be called the 404 anymore. The name is old and the changes aren’t visually striking.

The newest version of Zipp’s most versatile, workhorse aerodynamic 404 wheel, the Zipp 404 Firecrest Carbon Clincher, is so vastly (but inconspicuously) changed from previous versions the only thing in common with recent model year 404’s are the spokes and the hub. While that seems like a contradiction- it is not.
The Firecrest rim design is entirely new, from shape to width to aspect ratio and rim material. It isn’t a refinement- it’s a new design including dimensions and materials. It retains a similar rim depth but that is largely cosmetic since the rim has a “virtual” rim depth that results in reported drag numbers lower than any 60 mm deep carbon rim according to Zipp.

Zipp 404 Firecrest Race Wheels
The old Zipp 404 on the left, the new Zipp 404 Firecrest on the right: The difference in rim width is apparent.

To fully understand the new Zipp 404 Firecrest you must first understand Zipp. They are not a bike wheel company; they are a race engineering company. Located down the road from the Indianapolis Motor Speedway they have provided engineering solutions for racing problems in Formula 1 and Indycar since their start up. Sometimes those solutions are obvious and conspicuous, other times the solutions are minor and measured in fractions of a second.

Zipp 404 Firecrest Race Wheels
This is the only song in the Firecrest symphony that remains the same. Zipp retained their fine hub and reliable Sapim aerodynamic, bladed, stainless steel spokes on the new Zipp 404 Firecrest.

The challenge for Zipp was not to make a wheel that performed better on calm days at high speeds. That was easy. Zipp, HED, Mavic and others, have already done that. The challenge was to create a lighter wheel with lower rolling resistance, better durability, better ride quality and superior aerodynamics all the way down to low speeds. That is part of the Zipp 404 Firecrest agenda.

Zipp 404 Firecrest Race Wheels
Firecrest is not just aerodynamics: The profile of the tire interface is now wider resulting in claimed lower rolling resistance and verifiably nicer ride quality. The new, low profile Firecrest configuration on the left, the older Zipp 404 alloy rim version on the right. The difference in ride quality is very noticeable.

This project makes sense for Zipp from a business perspective. If you look at the rank n’ file of Ironman athletes especially, average bike speeds are below 21 M.P.H. It’s easy to build an aero wheel for the 23 M.P.H. and above crowd; the challenge is creating something that makes the middle of the pack rider faster also. Firecrest is an aero wheel design that Zipp claims will provide an aero benefit at higher speeds and down to lower speeds benefitting the middle of the pack rider. If you think about the logic in the design of Firecrest, there may be some substance to the concept.

“Firecrest is an aero wheel design that provides an aero benefit down to lower speeds benefitting the middle of the pack rider.”

It made sense for Zipp to begin the Firecrest re-design project at the 404. The 404 is Zipp’s bread and butter wheel. If you only own one aero wheelset a 60 mm rim depth aero wheel is a versatile choice. The 60 mm depth strikes a reasonable balance between weight, durability and aerodynamics making this wheel configuration the go-to on hilly, flat and rolling courses. Zipp 404’s have been ridden everywhere from the Olympics to the World Time Trial Championships to the World Cyclocross Championships and the Tour de France. Their versatility and overall performance are proven in every cycling environment. As such, the 404 was the obvious place for Zipp to begin an overhaul of their wheel technology.

Zipp 404 Firecrest Race Wheels
The quandary of wheel aerodynamics is that the wheel's leading edge is also its trailing edge at a different point in its radius. As a result, Zipp found an optimized shape; the Firecrest shape, to optimize performance of the wheel throughout its entire circumference.

The difference between the new Zipp 404 Firecrest and the previous Zipp 404 is a total rim re-design. The new Firecrest 404 rim is wider, has a more complex variable radius or “mean camber” and has a more rounded “trailing” edge and a different composite lay-up.

The quandary of wheel aerodynamics is that rim shape forms both leading and trailing edge depending on the part of the wheel you consider- it is more complex than a wing on an airplane which only travels in one direction. As viewed from the rider’s right side of the bike the 3:00 O’clock position of the wheel is where the tire hits the air first. However, at the back edge of the wheel, at the 9:00 O’clock position, the trailing edge becomes the leading edge. Additionally, the trailing edge is flowing through turbulent air, further confounding aerodynamics. As a result the vaguely airfoil shapes we are used to, with a thicker leading edge and a tapering rear 2/3rds to a sharp trailing edge aren’t as effective as the omni-directional Firecrest shape. On Firecrest both edges effectively act as a leading and trailing edge depending on their position in the rotation of the wheel. The shapes are optimized for both.

Zipp 404 Firecrest Race Wheels
The older Zipp wheel is on the left, with a thinner profile at the trailing edge. The newer Firecrest profile is on the right, with the more bulbous trailing edge that serves double duty as an effective leading edge.

 “On Firecrest both edges act as a leading and trailing edge depending on their position in the rotation of the wheel.”

The new Zipp 404 Firecrest is visibly wider than the previous 404’s with a maximum 25.3 mm width at the widest point. Zipp reports testing with 19 mm tires but the configuration I rode had Zipp’s 23 mm clincher tire, my choice for overall performance including flat resistance and ride quality. An interesting aside is a maximum tire pressure of 125 pounds on the clincher rim.

Zipp 404 Firecrest Race Wheels
We used the Zipp Tangente "Open Tubular" clincher tire on our test Zipp 404 Firecrest wheels. This Vittoria made tire is customized for Zipp with special aerodynamic features and an additional flat-reducing belt. The fit and finish of this tire and wheel combination is very good.

It was not exclusively advancement in materials that brought Zipp to Firecrest, but more advancement in computing power and analytics- the study of the way a wheel behaves at very low speeds and under very low pressures. Enhanced computing power, better wind tunnel analytics and more advanced materials all contributed to the development of the complex Zipp 404 Firecrest shape.

Zipp was not the first to the carbon clincher space-race but they claim best in show with the 404 Firecrest, saying the rim is stronger and provides better braking performance than any other carbon clincher- and than alloy. We didn’t torture test the Firecrest 404 and likely won’t at $2700 per pair. We did ride them extensively in the real world on rotten pavement and can report braking performance is excellent in clean/dry and dry/dusty conditions. Being in the desert, we can’t tell you about wet weather braking except to say that Zipp includes specific brake pads with the 404 Firecrest and these new pads delivered great braking performance on our rides.

Zipp 404 Firecrest Aero Race Wheels
A close up view of the trailing edge on the Zipp 404 Firecrest. Zipp's molding appears to have improved on the surface of the 404 Firecrest with a smoother, more consistent cosmetic treatment. Previous 404's showed minor cosmetic "pits" that frustrated some customers but had no functional effect.

For most customers the bottom line will be: is the new Zipp 404 Firecrest faster than the previous Zipp 404? We can’t provide an empirical metric to prove or disprove Zipp’s increased performance claims. In the analog we can tell you the new 404 does ride differently than previous versions even with the same tire. This is likely due to the wider rim profile and attendant affect on tire performance. Any difference in speed will be revealed on the stopwatch and the results page. These statistics don’t have much perspective until you miss qualifying for Kona by less than five minutes over a 10 hour race or you miss the last place in your age category at the local Olympic distance triathlon by 15 seconds. According to Zipp’s quoted statistics the Firecrest re-design would buy you those seconds. That’s a margin we can’t quantify. 

Zipp 404 Firecrest Aero Race Wheels
The previous Zipp 404 didn't look "old" until we put it next to the new 404 Firecrest with its full carbon fiber rim and fortified Firecrest aerodynamic/low rolling resistance configuration. The Firecrest design philosophy will also be used on the new Zipp 808 Firecrest to be raced in Kona this year by the top pros.

We can also tell you the ride is less “edgy”, feels more stable and sure-footed. Cross winds feel less gusty, and we have a lot of gusty cross winds in Tucson. Previous 404’s created a sensation of riding on a pair of razor blades- for better and for worse. If you favored higher tire pressures it was even more so. The new 404 Firecrest is a kinder, gentler aero wheel that rides better and claims lower rolling resistance along with lower drag coefficient. We can confirm better ride quality. While the new Firecrest 404 is 28% more money than the current sale price on the previous alloy rim Zipp 404 ($2700 for new Firecrest 404 versus $1959.00 sale price for previous alloy rim Zipp 404) there is a tangible argument for the wheel being a commensurate leap forward in technology- especially if you grant credence to the aerodynamic claims.

Zipp 404 Firecrest Aero Race Wheels
We've ridden many tire combinations on the old Zipp 404 in the left photo, on the left with the alloy rim. The wheel shown is my own commuter wheel with a flat-resistant, heavy Continental Gatorskin tire. We compared the old 404 to the new Zipp 404 Firecrest using the same 23 mm wide Zipp Tangente tire.

The Zipp 404 Firecrest is tangibly lighter than the conventional 404, 11% lighter for front and rear by our scale. A pair of Zipp 404 Firecrest Carbon Clinchers weighs 1487 grams on our scale while the older non-Firecrest 2010 Zipp 404 weighs 1662 grams. Since the hubs are the same the entire weight reduction is in the rim. Somewhat refreshingly, our production wheels weighed slightly less than Zipp’s claimed weight. The wheels both use Sapim bladed, stainless spokes. There are 16 spokes radially laced on the front wheel and 20 spokes crossed once on the rear wheel.

Since the introduction of the 404 Firecrest, Zipp has announced the introduction of an 81 mm deep Firecrest wheel called the 808 Firecrest, an equally substantial fortification of the previous 808 design. The new Zipp 808 Firecrest is a claimed 15 seconds faster at a given (unspecified) speed over the previous, narrower 808 design measured at 40 Km. The Firecrest 808 will hit sales floors in December with pre-production wheels under Zipp sponsored pro athletes on the Queen K in Kona. If Zipp’s claims about reducing drag at high yaw angles with the Firecrest concept are accurate the Firecrest 404 and 808 front/rear combination may provide Zipp athletes with an advantage in the well documented Mumuku crosswinds.

I’m satisfied with Zipp’s update of the classic 404 aero wheel. The original 404 set a high bar that lasted for years. The Firecrest update is tangibly different in dimensions, weight, ride quality and in claimed performance. It is a reasonable extrapolation to suppose a similar influence on performance given these changes. The new Zipp 404 Firecrest Carbon Clincher is likely the high bar for versatile aero wheels across a broad spectrum of race courses and average speeds. It is the everyman aero wheel made even better.

Zipp 404 Firecrest Aero Race Wheels
Because the original Zipp 404 was a strong product Zipp resorted to a full re-design of the rim to raise the performance bar with the new Zipp 404 Firecrest Carbon Clincher. With claimed improvements in aerodynamics and easily verifiable reductions in weight and easily verifiable improvements in ride quality it is likely Zipp has tangibly raised the bar with the Zipp 404 Firecrest Carbon Clincher.