The Zipp 303 road wheels just got a massive overhaul. They’re wider, with a new hookless rim. They’re aerodynamically optimized for 28mm tires, and designed to let you run lower air pressure. Separately, these are all good things.

Add it up, and Zipp says you’ll have a faster wheel no matter how rough the surface. Here’s how it all comes together…

MY2021 Zipp 303 S aero tubeless-ready carbon disc brake road bike wheels

How the Zipp 303 got here

The 303 series has long been Zipp’s all ’rounder, being tasked with everything from the classics on cobbles, smooth fondos, cyclocross races, and more recently gravel bikes. The mid-depth 45mm rims hit the sweet spot in aerodynamics and weight for most types of riding.

It’s been a while since they’ve been updated. The 303 got a tubeless version in 2016, which was a little late compared to some other wheel makers.

Now, they’re getting a major update to modernize the profile for wider tires, optimized for tubeless and disc brakes.

What’s new about the Zipp 303 rims?

2021 zipp 303s rim profile and shape
Real world product photos c. Jayson O’Mahoney/The Gravel Cyclist. All other photos c. Zipp.

A lot. They’re still 45mm deep, but that’s about the only carry over feature. These wheels have a new construction that helped bring the price down. Retail is now just $1,300 for the pair.

The rim is 2mm wider externally, pushing it out to 27mm. The important measurement is internal. By getting rid of the bead hooks, they increased inside width by 7mm. The new Zipp 303 S internal rim width is 23mm.

The new, wider rim profile is optimized for 700x28mm wide tires. And it’s optimized in several ways. First, aerodynamics. They say by removing the bead hooks, and not having to worry about a brake track, they could really smooth the transition from the tire to the rim.

And the wider rim better matches a wider tire’s frontal profile. Combined, it smooths the air flow and reduces drag when running wider tires.. But aerodynamics is only one quarter of the story…

Whatcha gonna do with all that space?

It’s one thing to just make a rim wider and say you can run wider tires on it. But Zipp had a lot of reasons to make the change. Besides helping to keep them relevant, it was really about making their pro riders faster on the cobbles and rough classics.

Their design and feature set had to evolve as gravel and all-road bikes have become more popular. It used to be all about aerodynamics, with a focus on wind tunnel testing, 40k TT performance and just plain beating the wind. Now, they have a four-pronged approach where efficiency equals speed, not just aerodynamics

For them, efficiency means beating wind, gravity, rolling resistance and vibration losses.

We covered wind. And gravity simply means reducing weight. The new 303 S wheels are 155g lighter at the rims (77.5g per rim) than the 302 Disc Brake wheelset they replace.

Rolling resistance and vibration reduction go hand in hand, so we’ll cover them together. By opening up space inside, and making the rims tubeless specific, they allow you to do two things: Run wider tires that are properly spread out on the rim, and run them at lower pressures.

how does a wider rim improve a bicycle tire contact patch

This means that a wider rim that pushes the tire wider will create a wider, but shorter, contact patch with the ground. The effect is that there’s less “tire sag”, which is how much of your tire sidewall is compressed where it meets the ground.

A wider tire won’t sag as much, so there’s not as much sidewall deformation, which means less friction and resistance. The result is improved rolling resistance efficiency. It also “looks” like it has more grip because of the fatter patch, but, technically, the actual contact patch size would the be the same…and they don’t measure for that.

MY2021 Zipp 303 S aero tubeless-ready carbon disc brake road bike wheels

Good, Good, Good…bye, Vibrations

Vibration Losses is a new metric for Zipp, and they had to build new testing equipment to measure it. They started by testing on cobbles, and the pros broke every prototype. But it was the beginning of making something that could stand up to any type of terrain.

The idea is to measure whole body vibration, then reduce it. With the current 2020 Zipp 303 wheels’ 21mm internal width, you have a narrower tire volume with higher pressure and rough terrain would transmit basically everything to the rider. As if to state the obvious, spreading that same tire size out and reducing the pressure reduces how much of that vibration makes it to the rider. Thus there’s less power lost to vibration, the more comfortable the rider is, and the faster they can go.

How d’ya like them Apples to Apples?

zipp 303 recommended tire pressures for 2021 wheelsets

This is important: The comparisons in contact patch and sidewall compression above are based on using the same size tire at the same tire pressure. They’re to illustrate the benefits of a wider rim when you want to run lower tire pressure. Trying to run lower pressures on a narrower rim won’t get the same results because they’re less volume to cushion the ride.

You’ll always have a tradeoff between support and reducing vibration and rolling resistance. Within a logical range, lower tire pressures will reduce both and help you ride faster. But the tire’s sidewall will compress more as you lower the pressure, eventually feeling squirmy and losing it’s ability to cushion against bumps.

Zipp says the chart above is their recommended starting points, then it’s up to you to play around with different pressures.

MY2021 Zipp 303 S aero tubeless-ready carbon disc brake road bike wheels

What’s the max tire pressure? Rider weight limits?

Max tire pressure is 72.5psi (5bar), and that’s with Tubeless or Tubeless-Ready tires ONLY. You can run tubes inside if you need to, but they say you need to run tubeless/TR tires because those tires have the stiffer bead necessary to work on a hookless rim design.

Rider weight limit is the same as all their other wheels: 250lbs (115kg).

They recommend a minimum tire size of 700×25, and maximum of 700×55. There is no 650B size offered in this wheelset.

2021 Zipp 303 S Specs, Pricing & Other Trivia

2021 zipp 303 s specs pricing and tech details with claimed weights

Technically, this wheelset is the successor to the 302 Disc Brake wheelset. And it’s 155g lighter than the 302 Disc, with the weight savings coming almost exclusively from the rims! That means a lot less rotational weight, despite the wider rims, and at a lower cost. Not bad, eh? They use Zipp’s 76/176 hubs with Center Lock brake interface and include the rotor lock ring.

Notice anything different? The graphics are a new logo and look for Zipp. We first saw this logo on their 3Zero MOTO Mountain bike wheels, and you’ll now see it moving across their road line, too. They’re permanent, meaning they’re not decals, which makes them a bit sleeker and saves a few grams.

Zipp 303 S actual weights

2021 zipp 303 S actual weights for front and rear wheels

The wheels come pre-taped for tubeless, and weights without valve stems are 717g front and 828g rear (1,545g total…right on target). Add two valve stems and the rotor lock rings and you gain 27g (13.5g per wheel).

MY2021 Zipp 303 S aero tubeless-ready carbon disc brake road bike wheels

Notice anything missing? Dimples. Which, along with the lower price point and lack of a Firecrest or NSW icon, suggests that there’s more to come with this new, wider rim profile. Stay tuned…

Zipp.com

33 COMMENTS

  1. Between this and the Enve Foundation series it’s nice to see some other high end wheel brands start to bring less expensive offerings.

    Personally not a fan that they have followed suit with Enve and decided to go hookless and tubeless only. I’d prefer a hooked bead for versatility and safety. Thankfully there is the Bontrager Aeolus 3V out there. 25mm internal width, a hooked bead and an MRSP of $1300. Mine came in at 1553 grams.

    • Been using hookless for road, cx, gravel, and mtb for years now and zero issues. What’s the internet’s problem with hookless again? Asking for a friend.

      • I’m not going tubeless yet.
        Still prefer Continental GP5000 with latex tube (at 65-70psi).
        Hookless doesn’t seem safe for non tubeless tires.

        • @Hexsense, sorry can’t take assumptions like that all too seriously. Maybe I should have been more clear. I’d like to hear a first hand negative experience, not armchair critiques which is all to typical regarding this matter.

          Let’s call this ‘The Hookless Challenge’. Answer my question if you actually ride them and be open and honest about any problems, because I’m just not having them. Fairly certain that I’m not an outlier.

          • https://www.velonews.com/gear/technical-faq-specialized-turbo-2bliss-tire-blowoff/

            If through experience, research or luck you have a good combination of tire and rim, hookless can be fine. The problem is the current lack of standardization that makes mismatches almost inevitable.

            There’s a new ERTRO standard for rims and tires in the works. Most of the large rim and tire manufacturers are on board. When released and implemented, the new standard may help simplify the use of road tubeless.

            • The subject in the article you reference was using a wheel set that was internally too wide for the tire. So I guess in this instance we shouldn’t surprised about the blow off. Chalk it up to user error. That being said I agree that once a standard is revealed the margin for error will be much lower.

              Just to put it out there regarding tire failures in general; I have about 3 decades experience of riding and racing on tubulars and tubed clinchers and lost count of how many defects I’ve personally come across. Apparently tire problems are not relegated to the odd tubeless set up.

      • Well I don’t know about the internet, but for me it the two big things are:
        1. I still prefer using (latex) tubes. It allows me to switch back and forth between different tires (which I like to do on a fairly frequent basis on my ‘all-road’ bike) more quickly and with less of a mess. And from a rolling resistance standpoint, it’s just as fast as tubeless
        2. When I am TT’ing I will run pressures in the 76-80 psi range depending on road condition for optimal performance/speed (as recommended by Josh Poertner’s tire pressure calculator). I wouldn’t feel safe doing this with a hooked rim given the potential for blowing off the rim (hence why some the manufactures have max recommended pressures).

        I don’t think hookless is horrible or that it isn’t fine in some situations for for some people, it’s just that it seems like it offers more benefit to the manufacturer (cheaper and easier to produce rims) than the end user (maybe easier to mount tubeless? maybe some other reason that marketing has come up with???)

  2. So, Zipp presents a set of wheels, made in Chinafor the lowest cost possible and still asks for a premium.
    Why go hookless? Because the rim is cheaper to make.
    Cheap spokes.
    Cheap hubs.

    You can buy no name wheels for half the price which will perform better.

    • Product development isn’t free. I don’t know Zipp hubs well but they’ve developed their own profile and cut the price in half. I own and ride light bicycle 38s on dt 350s but couldn’t imagine that they’re actually wind tunnel tested or refined.

    • Maybe Zipp should hire you to advise on what they should be making? No name wheels I’m sure come with warranty support and crash replacement programs. Then again what do I know? You seem to know what you are talking about and Zipp have only been making carbon parts for 30 years. They’d do well to ask your opinion before the next wheelset they release.

    • Hookless beads are the pressfit bottombrackets of the carbon rim world. Technology driven by manufacturers who are constantly looking for a way to save a buck instead of delivering quality goods.

      • yes, but your car and motorcycle have hookless – tubeless rims already… Hookless rims are not created by the bike industry. For cost reasons? No, just because for tubeless a hook is not needed, and a hook introduces a weak point in the rim structure, and functionally unnecessary as already said. Have you guys read the article?

      • Do you seriously think a bead hook saves anything worthwhile material or development costs?

        The only reason hookless isn’t universally adopted yet is because the road bike world is full of grumpy luddites that don’t allow innovations to take hold at anything faster than a snail’s pace. There are countless examples of this.

    • I’m a big believer in lacing up myself. Light Bicycle rims to hubs of my choice. Your argument is silly, the biggest advantage to Zipps over no name China wheels is that they’ll actually warranty wheels, they have the liability insurance to pay out you if there is a defect that you need to sue over, the Zipp brand has a much much much higher resale value than no name Chinese wheels. I could take my 404 Firecrests and sell them tomorrow for basically what I paid for them used 2-3 years ago. Also the spokes, nipples and hubs are probably better than most wheels you’re getting in this price range.

    • they are probably talking about aerodynamics with 28mm tires. The new rims are optimized for that width tire so it’s not surprising they’re more aero. The old rims with 23mm tires are no doubt more aero than the new ones at 28mm.

  3. “the 303S rim is also the first of its carbon rims to be manufactured outside of the US, being made in the SRAM Taiwan manufacturing site”

    Bummer.

  4. Boy that’s a very marketing tainted article…
    1) I would like to know if they fixed the noodle-like stiffness on their current 303 DB wheels.
    2) the entire story point toward “cheaper” wheel: hookless is easier to make, exaggeratedly wide impose lower pressure… then allow hookless tires stay in position.
    3) compare tires at the same pressure…. pressure must be adjusted to the tire size (very good article here https://www.bicyclerollingresistance.com/specials/grand-prix-5000-comparison) if you want to compare apples-to-apples… sure a wide tire roll better at the same pressure than a narrower… but it will also be crazy hard… adjusting to same vertical deflection impose lowering the pressure… then having the same rolling resistance. unless you need really low pressure, the benefit is gone.
    4) crazy wide rims are not “Faster” they are a patch to “not make terrible aero-performance of 32mm tires).

    For light gravel I would like them… if I need big-tires, low pressure, they will work. but they are not performance road-wheels.

  5. i mean cheaper carbon wheels are better for the consumer too no? i think there are many benefits with going hookless, but really these benefits shine as a system, when paired with the benefits of other technologies like disk brakes and tubeless tires.

    so you’re right, i don’t think these are for everyone, these wont be for you if you like dead simple tubed clinchers on hooked rims. but these wheels with a good tire combo will probably be at least as fast as a good latex tubed setup, with the benefits of much lower tire pressure

  6. Hooked TL rims are a hybrid, when going TL, hookless is the path forward
    Every M/C and car with TL tires use Hookless design, for safety
    Sorry Continental, you failed

  7. @bielas: Have you ever changed a car or motorcycle tire on the side of the road? Not changed a wheel, changed a tire off the rim? There is a reason they have industrial-sized machines to do that.

  8. @Padrote: Wheel manufacturers such as Enve have been pretty up front that hookless rims are easier and cheaper to manufacture. Sad that Zipp isn’t as forthright about it.

  9. Know the silca blog, I had the chance to discuss with a continental engineer that strongly disagreed with the extend of their results. they are several folds too big in terms of “very low pressure roll better”.
    Now for the confort, sure lowering the pressure improves, and sure the wider tires allow you to go lower (even proportional to their width that require naturally lower pressure). I rode in a lot of crap roads in the US but here in Europe all my rides are on “perfect to good roads” nothing rugous to the point you need 28 or above tires…

  10. I just listen to the zipp podcast about these wheels there calling these entry level which is great backed by a lifetime warranty. I heard a rumor that zipp gonna drop some more new wheels at the end of the month excited for that!!!!!

  11. Anyone know the rim weight? I realized it mentioned it was about 70g lighter than the 302 however I think I’m missing what the actual rim weight is.

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