New Firecrest 303s
 

Zipp put out a new generation of one of their most popular wheelsets. They're fat and hookless. New hubs.

While external width is only 1mm wider at 30mm, the rims use a hookless sidewall design that gives a 25mm bed and a much fuller tyre profile. This reduces the ‘waist’ between tyre and rim that could often trip up airflow and while the new wheel is 5mm shallower than the old 303 at 40mm deep, it’s actually tested faster in the wind tunnel and on the road.

The take-home is that using Zipp’s own 28mm tubeless road tyres showed that on rough/gravel/cobbled roads, a 70kg rider will roll fastest with 55psi in the front and 60psi in the rear. Using a 30mm you should drop to 50-55psi and even lower the fatter you go. Even on smoother roads, Zipp’s data suggests you only need a handful more psi to return a 10W gain over narrower rims and tyres at higher pressures. They’ve even deliberately rated the rims with a max of 72psi, not because more isn’t safer but because they’re determined to get people to try lower pressures.

https://www.cyclingnews.com/amp/news...st-303-wheels/

Good thing I don't ride on rough/gravel/cobbled roads and can use my skinnier and faster wheels and tires.

30mm. Yikes.

I’ve been pushing for wider tires and lower pressures for a while, so I’m glad to see it finally gaining traction.

But at the same time, I’m not convinced that 28s measuring to 30 are going to be faster for absolutely everyone - especially climbers who weigh less than 150lbs. The cynic in me expects the pendulum to swing the other way when they realize that, for a similar depth, narrower tires (on wide rims) are more aero, lighter and probably roll similarly if you go to a low enough pressure.

With TL and hookless, perhaps there is LESS reason now to go with wider tires than ever - just run your 23mm tires at 60-80psi. You’re not going to pinch flat anymore 🤷‍♂️

Wider tires, for now, seem to be a band-aid over the fact that hookless isn’t reliable at higher pressures and carbon rims are too delicate to take hard impacts frequently.

I was reading about these earlier today. IIRC, they're coming in at ~1350g for the pair for a wide, mid-depth rim - nice. That said, I'd be more tempted by the 303S, which seems to provide much of the benefit at a lower price, though they're not as light.

Hookless
This is the way

These sound more than a little reminiscent of Enve's 4.5 ARs. In the profile including 25 mm internal, in being extra fat, and in being hookless. These are about 150g lighter which at that kind of $$$ is nothing to sneeze at. I'd rather have the Enves any day of the week and twice on Sunday, but it's an interesting development and if I was going to buy Zipps it would be some flavor of 303s.

The Enve wheels were made for the cobble races, and are marketed for mixed surface rides where you want control on the gravel and speed on the pavement. I don't know the story behind the Zipps but they'd excel at the same kind of riding.

I've beaten the crap out of mine, and I'm built like a football player. Really amazed at the abuse they stand up to.

Look like great wheels. I always loved my first generation Firecrest 303s and like the 303 NSW as well. There’s a limit to how wide and low pressure I want to/need to go. I don’t feel at this point running my DR Swiss PRC 1100 wheels at 75/80 (with 26 mm tires) or my Zipp 303 NSW at a similar pressure (28 mm tires) needs much additional comfort - though I must admit I love the feel of open tubulars on both wheels. I’ve become a bit less aero-focused on wheels because I can get great flat road speed on my PRC1100 set without a bunch of weight, so they climb well. It sounds like these wheels are incredibly light! I’d love to give them a try for fun at some point.

We’re pretty lucky with all this amazing cycling tech that’s coming out. Lots of great choices out there.

Hmm... certain Continental tires are rated safe for hookless Enve rims.

What's the advantage of hookless over a hooked rim? It simplifies manufacturing, but why not a hooked rim that can run clinchers and tubeless? Except for a very small weight difference, this helps the manufacturers but not the consumers/riders.

IIRC, hookless are better in terms of impacts, it gives you a bit better sidewall/rim profile/transition, and it effectively gives you more volume. Also, simplification in manufacturing benefits consumers if the savings are passed on.

Less rotational weight which people make a big deal of, and a stronger more important resistant rim.

Just before reading this thread, I watched the GCN "review/paid content" video on these wheels. What intrigued me is the weight that WiFi has mentioned at 1352 grams. For a clincher disk rim that is excellent. They certainly made my short list for my next carbon wheels.

The real reason they push for lower pressure is to get away with otherwise dangerous, tyre blow off, but cheap to manufacture, hookless rims. Ppl drink the kool aid as if they reinvented the wheel ... They didnt.

Dangerous? Really? I've been on hookless rims for years. Haven't even died once yet.

Yes really. Most tyres are designed to work with hooked rims. - Im sure you can get away with hookless with a tyre that is specifically designed for hookless, or if you run a TL tyre at really low pressure. But then you are into experimenting and on your own.

Here is the ENVE, really short, hookless rim/tyre compatibility list. Look for all your favorites that isnt there.

https://www.enve.com/en/lp/tire-compatibility/

The lack of compatibility is what the GCN infomercial didnt disclose even ift its really important from a practical AND safety point of view.

Except that you lose pretty much all this benefit by being forced to use 28mm tubular tires, which are likely atleast 100gm heavier apiece than the lighter 25c. And you get a shallower rim.

These are aimed squarely and unapologetically at those that have bought in to wider, tubeless tires - folks that would be running 28mm+, regardless, so I see it as just... benefit, not trade-off.

Also, 100g heavier apiece? Nooooo - the new 28mm Pro One TLE Addix are ~270g each, the 25mm are ~245g.

Enve's take on why evidently there are tires that aren't compatible:

"So herein lies the number one problem in road/gravel tubeless innovation today. Rim manufacturers have outpaced the rate at which some tire manufacturers have innovated, creating a complicated environment for consumers when it comes to pairing tires with their new state-of-the-art hookless road or gravel rims."

Gallons and gallons of kool aid :-)

Removing the hook is no more innovative than making rims with a non standard diameter and then blame the tyres for not fitting, lol. Enve and zipp are the one causing complications and confusion, not to mention possible danger to unsuspecting customers that may not notice or be aware of the the danger mounting at standard tyre to a hookless rim, that at a glance looks and feels compatible, but isnt. - At the very least such a rim should be plastered with warnings or be larger to a degree that no standard clincher could be mounted.

We get it - it's not a product or product segment for you. Why not just move along?

Ah, fair enough re the fact that most people might want 28mm or more tires anyway. Was too biased by my own preferences....

​​​​​​Thanks! Is water wet?

My favs are the IRCs, followed by Pro Ones. Funny that they're both on the list.

You only mount tires that work with your rims. Kind of like in your car. Are you telling me the danger is that you're going to crash while texting? That people who don't know that they're taking about won't like your setup?

Funny? You decide ...

https://cimg3.ibsrv.net/gimg/bikefor...182f0edc30.png


https://www.schwalbe.com/en/tubeless...danforderungen

But Sure, You Enve and Zipp knows better. Right?

As @WhyFi pointed out, the fast and supple tires today are pretty light.

Does it matter if the rim is shallower if it's faster? That just means less weight, and less vulnerability to cross winds, right?

But that design choice [hookless] has allowed this wheel to become more efficient overall. It has a more bulbous rim profile that allows the tire to sit wider, meaning less tire deflection, a shorter contact patch and reduced rolling resistance. Energy lost to vibrations in the road has also decreased thanks to higher volume tires running at lower pressures.

https://pelotonmagazine.com/gear/the...ious-overhaul/

This would be measurable. When climbing, small improvements in Crr dominate small improvements in either aero or mass, and we can measure all of those.