Zipp introduces their new Firecrest track wheelsets in the “404” (58mm deep) and “808” (82mm) rim versions. Another touted feature is the new “303” track hubs.
So I guess SRAM feels like they can still eke out some cash from the Red Hook Crit crowd. Maybe I’m just a Debbie Downer, but the brakeless/fixie criterium racing seems like the tail end of the fixie boom/fad of the ’00s.In a way it somewhat parallels the BMX boom of the early to mid-80s when BMX racing carried on in pockets of this nation while trickriding/freestyle disappeared until the X-Games era. That’s not exactly analogous because BMX racing wouldn’t have existed/survived without the progression of junior/juvenile age-groups, whereas the Red Hook Criterium series is the logical evolution of underground, unsanctioned alley cat races into corporate-funded “unsanctioned” live entertainment. Well, maybe “brakeless track bike criterium” racing will show sustainable growth or maybe it’ll just live on as search words for cycling crash video clips on Youtube, only time will tell. Regardless I can’t see these Firecrest track wheels as being the first choice for track cycling’s elite, because the whole Firecrest design philosophy was optimized for road cycling, not track.
The whole point of the Firecrest wheels was to develop a rim shape that produced low drag numbers at a relatively wide range of apparent wind angles (yaw). A wheel being driven forward experiences an apparent wind vector that is influenced by the speed of the bike and the direction/angle of the wind due to the environment. Basically that means that the resulting vector is almost always a few degrees to either side of dead ahead. Ideally the form of the rim should be narrow to reduce cross-sectional drag (basically the force required to punch a hole in the wind equal to area of the bikes cross section) and also promote smooth, non-turbulent airflow around the surface opposite of the side the wind comes from. The wide, bulbous shape of recent aero wheel designs such as Hed’s current Stinger wheels and Zipp’s FIrecrest series are designed around those goals with maximum sectional widths of 26-28mm, whereas wheels before about 2005 invariably had long teardrop shapes no wider than 20mm (to keep cross sectional area to a minimum) with sharp trailing edges. The newer aero wheels (as well as aero frames and other components) give lower drag numbers over a wider range of real world riding condtions….on the road.
Racing on a velodrome isn’t the same as a road race, time trial, or triathlon on the road, especially indoor velodromes. At the World Championship or Olympic level, indoor 250m tracks are a pre-requisite, so there never is a breeze to give any angle to the apparent wind. In such a case, reduction of cross-sectional area remains a higher priority. That’s why you don’t see those big bulbous rims at the top levels, because those shapes are slower in those windless conditions. In fact, the fastest non-disc aero wheels seem to be designs such as the Mavic Io and Corima 4-spoke that date from the early to mid-‘90s. The Hed 3 was originally designed in the late ‘80s and is still used competitively today. Ironically, all those hours people have spent in wind tunnels to devise more sophisticated aero wheels has led away from those older shapes that still do best on the track. And though I’m just barely touching on the topic of disc wheels and track racing, rear discs are used almost without exception at the top levels, and front discs in many non-mass start events. A fine example is Bradley Wiggins set the latest hour record with front and rear discs.
Yes, there are a lot of recent trends for road bikes that have no traction in track racing. I’m specifically talking about WIDE tyres, a subject that Bike Hugger has often discussed these past few years. Yet I still see people rolling around on cyclocross bikes with 23mm tyres for city use for some reason. For some people like Compass Bicycle’s Jan Heine, wider tyres for performance riding has become their raison d’etre, but all the ProTour teams have moved to 25mm tyres for even the smoothest roads when once they would have been on 21mm tyres nailed at 125psi. The idea is that a tyre with a larger volume combined with a supple casing can have the same or less rolling resistance as a narrow tyre, and the larger tyre can do this at lower air pressure. The lower air pressure means the rider’s mass bounces less, and with less bounce there is also less energy lost from driving the bike forward. The kicker is that these wider tyres also work better with those new, wider aero wheels. Cool, right? Why of course it is, but it’s all mainly useless for track racing. Those guys will stick to 19-21mm tyres at 160psi plus because the best track are deadly smooth and they will be using narrow wheels. I think I heard that Wiggins used 200psi plus for the hour record and that is certainly plausible.
But what if you aren’t Bradley Wiggins or Gregory Bauge? What if you don’t race on indoor velodromes? Because most of us don’t. Then the Zipp Firecrest track wheels could be optimal for you. On a slightly bumpy outdoor track like Marymoor’s 400M oval, a windy day can totally change your tactics. It would certainly be desirable to have a front wheel that performs well at various yaw angles. Having a non-disc rear wheel is nice in the sense that it might reduce rotational inertia and perhaps be more versatile, but a disc might still be better choice in race conditions. Admittedly, this is all fine margins we’re talking here, and of course the difference between narrow and wide aero wheels isn’t going to put packfodder onto the top step of the podium. And these Firecrest rims are quite fast even in indoor conditions after all. It’s just at the top level the riders wouldn’t give any advantage away.
As for the Zipp track hubs….meh. You’re buying the wheels for the rims and you can’t buy the rims a la carte. Zipp has a patchy history of road hub designs (I’m being polite here), but their track hubs have been competent though never remarkable. The concept of a “wheel system” is a little weak in this circumstance, as the rim and spokes are clearly off the shelf items while the hub design isn’t breaking new ground. Zipp uses a conventional high-flange design with a bolt-in axle, so you tighten it with a 6mm allen key. The allen key method is convenient because the necessary tool is small, but you’ll never get as much force as if it used 15mm tracknuts. I never liked that the 6mm bolt-in axles personally. But I guess a lot of mass produced track bikes have built-in chain tensioners, so maybe the extra security of 15mm tracknuts threaded onto 10mm axles is superfluous. I do find it odd that Zipp chose to use 28 spokes front and rear on rims that they would only use 24 spokes if they had disc brake rotors.…