Exact same idea as the Zipp FC and HEDs. Wider rim with leading/trailing edge aerodynamic principles, and designed for 10+ degree xwind. They look pretty nice also. If anybody is planning on buying new wheels, the D3, FC or new Heds are the way to go IMO.

I've got multiple sets of Zipps. Old 404's, 303's with the torroidal, dimpled, rim, 808's with the torroidal rim, and now 404 FC clinchers.

I can't say I can tell any speed difference between the new and old 404's. Of course, any difference would be small enough as to not be perceptable.

As for handling in cross winds, the new design might be a little less prone to getting moved around. However, I haven't ridden them enough in stiff winds to convince myself that's true, or to rule out the placebo effect.

ENVE 5 year warranty. Light and lovely. Have a set of the 45's and love them.

I've got a set of 303 FC...they're nothing special. I certainly thought they would ride nicer than they do. They're heavy as well. Go with ENVE.

Clincher or tubular? What year? I just picked up a pair of 2008 clinchers but haven't had a chance to ride them yet. Need new cassette, skewers. Besides the extra weight, what don't you like from them? What were you expecting?

I don't care what you've ridden. The data is well established, it's not just Zipp. Most companies who actually use wind tunnels and cfd to design their wheels have figured out that the best way to design a wheel is from the nose->out, with essentially a cut off blunt airfoil.

In Tour's most recent data, with data translated to 25mph, the Zipp 808 had an aero drag equivalent to 6.2 watts; the Hed Jet 9(similar shape but non parallel brake tracks) measured 9.3 watts and a deep V Cole rim(similar to what Boyd, et al use) measured 13 watts. All well outside of the margin of error for a good wind tunnel.

There are similar differences for shallower wheels. And actually, ironically enough, some of the shallower wheels can have greater disparities than the deeper wheels because shape and spokes matter more.

Anyway, to the OP, Bontrager has a new type of wheel out so anyone giving feedback on the old wheels may not be as relevant to your purchase because they changed from a carbon fairing construction to a solid rim like Zipp. Though, I also don't know what your LBS is trying to sell you. The difference between your carbones and the older 404 shape would be more about weight and less about aero.

I'd say that just about all the wheel companies using the new blunt inner edge, wide, curved walls should be a good step up from your Carbones. Enve, Bontrager, Hed, Zipp and Rolf are all using a newer rim shape like this.

^^ The Tour magazine tested the old Jet shape (i.e., not SCT). Enve's testing put HED ahead of the Zipp FCs.

AFAIC, I take it to mean that Zipp and HED are pretty much at par in terms of performance.

I ended up going with HED Stingers, simply b/c (a) they are cheaper (although I'd have spend the extra $$ if I felt the Zipps were better) and (b) you see quite a few Pro-Tour guys riding re-badged HED wheels or rims and (c) Stingers are tough enough to be daily-riding wheels.

The old 404's weren't all that bad in crosswinds. I used to have a set of Ksyrium ES's that were worse. The new 404's feel a little better to me in a crosswind than the old. Maybe I'm more sensitive to that because I weigh 135#.

I race on 404FC tubies. It's not that they don't get pushed around in a heavy crosswind, it's that the push is balanced so that it doesn't create turning moment. I got the Zipp tubies because they are both aero and light, so I can use them no matter what race is on the schedule: crit, RR, HC... whatever.

The only issue I've had, and it hasn't been diagnosed beyond reasonable doubt, is some front end wobble at speed. The wobble is limited to the front wheel - it isn't that harmonic wobble that involves the entire frame. At high speeds, with the wind direction fluctuating, the front wheel gets a bit "skitterish". Enough that people have commented, and well, having the wheel move around at 45-50mph in a RR pack is a touch off-putting. I think it is the laminar airflow attaching and detaching from the foil. The wheel appears to seek a line through the wind fluctuations. I just had a new tire put on, however, and looking at the old one with no air, I don't think the glue job was particularly good. In fact, I got a clicking from the valve stem on the rim, and think that indicated a possible gluing issue. In any event, I haven't experienced the wobble on the new tire, but then I haven't ridden in the same conditions - crit's only so far, and without significant wind. So we'll see. But I love the wheels in all other respects. My training wheels are Bont Race XXX clinchers (paired spoke version), and they are also light and ride great, but I'll take the Zipps any day. If it weren't for the hassle and cost of tubular repair, they'd never leave the bike.

Manufacturers like Scott have adopted cut-off foils for frames to get around UCI rules controlling ratios, however the rounded section on the latest wheels has more to do with the fact that the "back" of the rim is also a leading edge, particularly when the apparent wind angle (please don't say yaw!) starts moving to the side.

Well I know that, its why they design, as I put it, from the nose out. I was actually referring to the kamm tail concept as the tire being on the trailing edge of the airfoil. I also suspect that the blunter airfoil(than for say a bike tube) is the result of the horizontal aspect ratio being so varied acrossed the wheel.

You're right that the hard part about understanding for consumers why "deep carbon wheels" perform so differently is the variety of ways in which the air passes over them. Tire as leading edge, tire as trailing edge, tire as leading and trailing edge(think top and bottom of the wheel), the way in which the wheel "pushes" air. It seems to be easier to say "yay, carbon wheels are fast" than to actually consider how the wheel moves through the air and how the tire effects the system as a whole.

303 FC clincher

Heavy as hell? They are under 1500 grams.

Well said.

That's heavy...especially for the price.

That is a great warranty, but I'd still get zipps. Nobody to date has melted a Zipp FC, but there have been melted Enve's. Enve does replace melted rims under warranty, but at 45mph coming up on a 2 mile set of hairpins, I don't even want to have to worry about it.

A large bulk of the population probably doesn't have to worry about those circumstances, but people in in CA or the rockies might care. The OP didn't have a location listed.

^ I have yet to hear of a melted FC CC either. IIRC, there was a thread on RBR a few months back where a few guys warped their "Edge" labeled wheels.

I just picked up a pair of 404 FC tubulars. I don't have enough miles on them to really make a comparison.

According to Competitive Cyclist, the 303 FC clincher weighs 1527. The 2009 is closer to 1700 gr.

Go Enve or go home.

That's the clincher...the tubie is way lighter

The 303 firecrest tubulars are 1200g. It's also extremely durable with the redesign. Kevlar channels to take the impact from Roubaix.