Let’s start with the full disclosure. We get wheels from Zipp in exchange for the ad up there, and part of the deal is we do a write-up on the wheels. This year they were eager to push Firecrest carbon clinchers, so I wound up with 808’s and Schmalz and Alex got 404’s (Alex's contributions are in italics). You can drink the Kool Aid and watch tires explode in a video here.
The biggest new feature of the Firecrest wheels is the rim shape. Zipp had the obvious (in retrospect) epiphany that the rim should be optimized to cut through the air with the tire as both the leading and trailing edge. A quick perusal of the latest offerings from Hed, Enve, 3T, and Shimano would seem to suggest that Zipp are on to something. I wouldn’t be surprised if the Firecrest profile completely supplants the familiar vee shape in a few years.
The resultant wheel is supposed to be dramatically faster than the previous 808, especially in a crosswind. I have no idea if that’s true, but I did find that I had to tap my brakes quite a bit in a pack, and the boss asked me if I lost weight.
The 808’s came in at 810 grams for the front, 919 for the rear, slightly below claimed weights. There’s still a weight penalty with clinchers vs tubulars, about 100 grams per wheel. The 404 carbon clinchers are claimed 1557g for the set, 1278 for tubulars.
All three of us rode these wheels preaty hard. Dan and I raced them on the crappy surface of Floyd Bennett Field, and Alex and I trained on them exclusively for three months or more. All three sets are rolling along just fine. My front wheel survived a particularly nasty square edged pothole strike at 26 mph in a TT, with my weight fully on the aerobars. It was the type of hit that cracked my 404’s of a few years ago.
Zipp resisted making a carbon clincher until they could make a brake track that wouldn’t soften and split from the heat of extended braking. The brake track they came up with is almost as good as aluminum, using both the cork pads supplied and Kool Stop black pads. Power and modulation were both excellent, smooth and not grabby. The Kool Stops needed a little toe in to not squeal, but once adjusted they were silent but for a bit of squeaking while stopping on the steepest pitches. In the wet they sometimes needed a quick squeegee before grabbing.
Alex: I remember riding first generation Reynolds all carbon clincher for two weeks many years ago. Around corners they flexed like crazy. Hitting the brake was not so much about stopping the bike, as making a gentle suggestion and hoping for the best. In the rain it was even worse.
Zipp has done a remarkable job of almost matching the braking performance of aluminum rims, the brake tracks are far better than those of any carbon rim I have ridden. In the rain, though better than past generations of carbon rims, they still bite and whine like they were freshly oiled. The supplied Zipp pads are excellent but wear quickly and cost 75 dollars to replace. I opted for budget Reynolds carbon-specific pads after 3,000 miles had chewed through my Zipp shoes, but braking performance on the cheaper pads was noticeably inferior.
The conundrum with deep sections wheels is that they’re a handful in the wind, yet offer the greatest performance advantage in crosswinds (Firecrests have the least drag at 15 degree yaw). In other words, if you want to get the most out of deep wheels, you have to be willing to ride them when it’s scary and gusty.
An accidental benefit of the Firecrest profile is that the center or pressure exerted on the wheel in a crosswind has moved back, in line with the steering axis. So while a crosswind from the left would force a typical deep dish wheel to turn right, it exerts no turning force on a Firecrest.
In practice this meant that I didn’t need to fight the wind. On blustery days the wind would make me lean one way or the other, but not affect my line. Once I realized I didn’t have to steer into a gust I just relaxed and kept pedaling. I did a road race and a time trial (with a disk in the rear) at the notoriously blustery Floyd Bennett Field and didn’t worry about the wind one bit, even in a pack. But let’s make one thing clear: as good as these wheels are, I eagerly returned to training on my 101’s. The 808’s are good but they’re mentally taxing when it’s blowing – you still get pushed around, you just don’t have to react to it as much.
Alex: At my size guys whistling for a cab threaten to blow me over. Going over the GW bridge on windy days had me fearfully eyeing the water below. High profile rims have a lot of surface area, so if you are used to low profile wheels its a bit like having a sail lashed to your handlebars. If the engineers at Zipp say they are substantially better in a crosswind than comparably deep rims, who am I to disagree? But still, they haven't defied any laws of physics with these rims.
I’ve had a couple of issues with wheelbuilds from Zipp in the past, a 404 with low spoke tension, and a 101 rear that requires truing every few months. My 808 rear was a fraction of a millimeter off dish (I had to guess since my dish stick doesn’t work with the rim bulge). For me this is a lesser sin – I can re-dish a wheel in 15 minutes but I’ll never be able to engineer a better rim – but it’s a concern nevertheless.
Alex: I have been riding them everyday and they have held up admirably aside from a few loose spokes, but I can’t say I would recommend any carbon wheel for everyday riding in NYC. If you are nervous about riding your tubulars to and from local races this could be an excellent solution as the weight penalty is negligible and the wider rounder profile make them less fragile than other all carbon wheels.
At 24mm wide, these wheels have the same nice ride first found on Hed Ardennes. Tires are wider and less squirmy, and the larger volume lets you run lower pressure with less risk of a pinch flat. A wider contact patch should theoretically have lower rolling resistance as well. The stability of the ride was palpable while switching between them and narrow rimmed wheels – I was surprised at how dramatic the difference was.
The rim measures 16.3mm at the inside, compared to 13.1mm for a Ksyrium.
(Speaking of width, the rim is 26.5mm at its widest. I’ve heard some people have had issues with clearance, you’ll want to check your frame before you get these.)
I ran the 808’s with normal tires and butyl and latex tubes, the latter of which felt as giddily fast as a nice tubular. I then converted them to tubeless. It took a lot of experimenting, but I eventually found that you need to tape up the rim with Stan’s 25mm MTB tape instead of their standard road 21mm tape. The rim bed on these wheels are textured and Stan's tape won't make a seal against it. The wider tape creeps up the sides and makes a seal against the tire bead.
Tubeless might be a tad slower than a regular tire with a latex tube (or it might be way faster if you ask Stan’s), but I haven’t had to change a flat on the road in 4 years of going tubeless and I like that security.
Alex: I spent an afternoon testing the wider profile rims of my Firecrest against some standard box section rims to refresh my memory – my impressions of a new setup fade faster than my state line sprint. I have been riding 23 mm wide Hed rims for the past year and I have been completely sold on the wider contact patch. You know that feeling of comfort and stability when you ride a street bike with big fat tires? Well it’s not as good as that, but the wider tires are noticeably more stable and confidence inspiring, especially when descending at high speeds or riding rough or cracked roads. This effect is compounded by riding the tires at 85 pounds. I have found the combination almost impossible to pinch flat as well.
Compared with my Hed wheels tires on the Firecrest rim are rounder and a bit stouter in the middle with even less "lightbulbing" of the tire – that's the shape the tire makes when it sticks over the rim of a conventional rim, ‘muffin-top’ must have already been patented. I don’t have the benefit of a wind tunnel in my apartment like Andy, but it makes sense that this would be more aerodynamic, it’s definitely less squirmy.
A 23mm Hutchinson Fusion is no wider than the rim.
Alex: Weight and aerodynamics comparisons make great ad copy but aluminum is still noticeably stiffer while cornering or sprinting, and I think that has become an underrated consideration when comparing wheels. So while these wheels are much stiffer than most any carbon wheel they still lag behind aluminum.
I totally disagree with Alex on that, and I’m heavier and pack a bit more punch in a sprint. Deep carbon rims are inherently stiffer than aluminum rims (an unbuilt Open Pro rim can’t support your weight, but you can sit on a 404 or 808 rim), and they’re built with shorter spokes that triangulate to the rim at a more severe angle. All that points to a stiff snappy wheel, and that’s how I found these wheels.
I also found them to have a buttery smooth ride. I don’t know if it was the carbon rims muting road buzz or the suspension of the wider tire cross section and lower tire pressure, but my 101’s had a substantially rougher ride.
With a deep rim you need a long valve, and you get an unbalanced wheel. At first I got a shimmy every time going down a 40 mph sweeping descent, with different tires and different bikes. After looking into all other culprits I balanced the wheels with a couple of wheel magnets per wheel opposite the valves, which cured the shimmies. To confirm this I did back to back descents with and without the magnets and am relatively sure that the imbalance was the cause of the shimmy.
Now, Jobst Brandt would say the imbalance is too slight and the movement of the wheel is constrained by the rider (then he’d probably call me an idiot). Furthermore, the vibration caused by an unbalanced wheel are on an plane perpendicular to shimmy. All I know is that it was scary as hell without the counterweights. My guess is that the tiny vibrations get amplified by a harmonic effect at certain speeds, and that nervousness makes a 90 degree turn and becomes a shimmy if the rider tenses up or is hit by a sudden gust. Now, most wheels aren’t balanced, so I have no idea why this effect was so pronounced on the 808’s.
This wouldn’t be my wheel of choice for long descents, but at their weight they wouldn’t be the choice for the ascent either. For the flat racing I'd use these wheels, the imbalance wouldn't be an issue at all.
Alex: Shimmying can arise at speeds above 45 MPH especially with a bit of wind, however my shallower 404’s didn't seem to be as affected as Andy's 808’s so I don't need counterweights.
Let's face it, the 808 carbon clinchers were made for triathletes – they’re aero, the weight penalty is less significant with steady speed riding, and you can change a flat – but they’re also good for flat road racing and the front doubles for TT duty. 404 clinchers would be a better all around wheel for roadies, and the wide rim ride is sweet enough to make you leave tubulars behind.