Check out our YouTube channel to see our independent and sponsor-free video reviews.


If the Zipp 303 S Tubeless Disc-Brake wheelset I rode for this review didn’t have the Zipp logo on the side of its rims, I wouldn’t have guessed it was from Zipp.

Regardless, it’s clearly a best value carbon wheelset winner.

It has better than average lateral stiffness and average vertical compliance (aka comfort). That’s the opposite of almost every Zipp wheelset I’ve ever ridden, and I’ve ridden quite a few in the 202, 303, and 404 series.

The high lateral stiffness is certainly welcome. Over the years, I’ve suggested to many larger or heavier-than-average readers that they go with a stiffer wheelset than those from Zipp. Lateral stiffness also translates to good handling in these wheels and effective climbing for a wheelset of its weight.

Less than Zipp-like comfort in the 303 S isn’t a knock, and it’s certainly not an issue. These are more like the comfort of the average mid-depth carbon wheelset. I did many 50-mile rides on them without any compliance-induced fatigue. It’s just that I had just gotten used to Zipp wheels being supremely comfortable.

Despite their 45mm depth, I felt only a small amount of “free speed” with the 25mm Schwalbe tires mounted on the 303 S. The pedaling effort (aka “watts”) I put into creating forward momentum with the 25mm and 28mm Zipp tires didn’t feel any easier to maintain as it does with more aerodynamic wheel-tire combinations when my speed gets above 20mph.

Knowing this, you can certainly make these wheels ride more comfortably by using a 28mm or wider tire without paying an aero penalty.

The 3-pawl Zipp 76/176 hubset is one of the few design aspects or components that carry over from earlier generation Zipp wheels. It’s pretty basic and pleasantly quiet; there’s certainly nothing objectionable about it. But don’t expect to get the same performance and smooth rolling of the Cognition hub Zipp puts on its NSW wheels just because they have the same logo.

The 303 S wheels did take notice of crosswinds but didn’t trouble me much about them. That was a very good thing as they climbed very well for a wheelset of its depth and weight.

Zipp 303 S

Also new for Zipp, the 303 S wheelset and the latest 303 Firecrest are the first in their new gravel wheelset category. While what qualifies as a gravel, road, or cyclocross wheelset or one well suited for all those disciplines these days is debatable, the 303 S internal width helps make the gravel argument.

From my testing, however, the 303 S rides on gravel more like most 21mm road disc wheels that are only slightly narrower than this one’s actual 22.5 mm internal width (per my measurement) and not nearly as well as the 25C rim width 303 Firecrest and others I’ve found are best for 35-40mm wide gravel tires.

Many ride 21mm (and 19mm and even 17mm) road wheels on gravel. You can certainly ride these as I did for miles on various dirt and gravel terrain. But these and other 21C wheels lack the comfort and handling of the best gravel wheels.

Because it’s a Zipp wheelset, I’ve reviewed it as critically as I would any wheelset that sells at historically Zipp-like prices. But this Zipp wheelset sells for far less and should be compared to those from other brands in this review of value carbon wheels that sell in the same price range.

Given its combination of stiffness, handling, climbing, and acceleration performance that is better than most others in this category, along with Zipp’s broad dealer service network and lifetime warranty, this Zipp 303 S is a value bike wheelset “best” pick for those who are committed to getting the lower rolling resistance of tubeless tires and know that they don’t gain anything by using hooked rims.

Zipp 303 S

Design: As mentioned, the Zipp 303 S tubeless disc brake wheels have hookless rims that require you to use tubeless tires. Most of the better tubeless tires are hookless compatible. Even 200lb/90kg riders needn’t inflate 28mm tires above the recommended 72.5 psi/5 bar maximum inflation pressure. what i

While most tubeless wheels these days have hooked rims that will lock in the flexible beads of tube-type clincher tires and give you the option to choose between going tubeless or tubed, you can only use tubeless tires on these wheels. If you prefer to use clinchers, these wheels aren’t for you.

The wheels weighed 1556 on my scale with pre-installed rim tape but no tubeless valves. They measured 45.2mm deep with a 22.5mm inside and 27.5mm outside rim width. The rim profile starts V-shaped at the spoke bed and quickly transitions to more of a parallel U shape.

Zipp uses their 3-pawl 76/176 hubset on the 303 S, one they used previously on the first 302 and earlier 303 Firecrest disc brake wheels. There are 24 bladed, j-bend spokes on the front and back wheels with external nipples.

The rims are made, and the wheels are assembled in SRAM’s Taiwan factory.

Zipp 303 S

The hookless Zipp 303 S rim tape should say Tubeless “ONLY” instead of “Compatible.”

Quality: Like many lower-priced wheelsets, the hubs use push-in end-caps. That’s usually not a problem. But, if you frequently remove the 303 wheels from your bike and change between road and gravel tires, it’s not difficult for the end cap on the freehub to pull off from the weight of the cassette. It happened to me on a couple of changeovers, and I had to scramble to put a pawl or two back in place. I was more careful after that.

Most notably, Zipp now gives the original owner of their wheels a lifetime warranty on any materials or workmanship defects. If it fails while riding or racing a wheelset in the way it was intended, they will repair or replace it at no cost to you for the lifetime of your ownership. That’s about as good as it gets.

Zipp doesn’t offer a trial riding period as some other brands do. They leave that up to their individual dealers to determine whether to credit or refund you if you want to return one of their wheelsets after riding it.

Like other major wheelset brands, Zipp has an extensive dealer network of bike shops you can bring your wheels into for any repair or warranty issues regardless of where you purchased them.

Price: The 303 S wheelset lists for US$1400, £1090, €1320, a very un-Zipp-like price. It often sells for less.

You can order the 303 S at stores I recommend for their competitive prices, great selection, and high customer satisfaction ratings using these links to Competitive Cyclist, BTD (BikeTiresDirect)Merlin, Sigma Sports, and BikeInn.

In The Know Cycling is ad-free, subscription-free, and reader-supported. If you want to help keep it rolling without any added cost to you, buy your gear and kit after clicking the store links on the site. When you do, we may earn an affiliate commission that will help me cover the expenses to create and publish our independent, comprehensive, and comparative reviews. Thank you, Steve. Learn more.

You can read my evaluation of other wheelsets in this category in the post The Best Value Carbon Wheelset.


  • How does the Bontrager Aeolus Pro 5 TLR compare to the Zipp 303S? Separately, and I realize this is a category above, but have you ridden or do you ever plan a review for the Bontrager Aeolus XXX 6 TLR disc wheel?

    • Kevin, I reviewed the Aeolus Pro 5 TLR and the new Aeolus Pro 37 in this review of the best carbon wheelsets for the money – part 2. I recommend the 303 S and Pro 37. As to the Aeolus XXX 6, we are testing it now along with a handful of other aero road disc wheels listed in this Know’s Notes post. I expect we’ll have those reviews up late July or so.

      You can always enter in a wheelset you’re interested in by using the search bar at the top of the page to see if we’ve reviewed it. You can also sign up to get new posts emailed to you or follow our social media to keep up with what we’re reviewing. Cheers, Steve

  • Hey Steve,
    What’s the point of $1300US wheels that don’t feel like more than “a small amount of “free speed”” even with the most aero tires. You’re recommending them, but isn’t the point to go faster. If they aren’t particularly go-faster…? $1300US is less than the best wheels, but it ain’t cheap. Read to me like they’re in ‘no-man’s-land’. Am I reading you wrong?

    • Same question as Cam, I understand the price point is lower but how do they stack up compared to the others if you were to apply the same + / o / – rating has you have to some of the other wheels?

      • Cam, Shawn,

        There’s a handful of performance considerations that go into my evaluations. Aero performance is just one. While we’d all prefer to pay as little as possible for carbon wheels, my experience testing a lot of “value-carbon” wheelsets in the $1000-$1500 range is that they just don’t perform as well or across the range of performance criteria I use as do the “performance-carbon” wheels that sell for $2000 and up. I did a comparison of wheelset performance of these two categories (and the alloy wheelset category) in my review of value-carbon wheelsets here that you might want to take a look through.

        Summarizing, performance-carbon wheelsets are generally going to be more versatile, aero, responsive, and comfortable than value-carbon or alloy-upgrade wheels. Many will also be stiffer, handle better and climb better too but I’ve found that depends more on the specific wheelset than its price.

        Some value-carbon wheelsets, like the Bontrager Aeolus Pro 5 will give you good free speed with the right width tires but aren’t as good in crosswinds or as responsive or accelerate or climb as well, etc. If speed is what you are focused on and you ride the flatlands without much wind, that could be a good choice for your situation at this price. Nearly all the value-carbon wheels have multiple weaknesses rather than the balance of equal or better performance the higher-priced performance-carbon wheelsets do.

        Compared to other value-carbon wheelsets in the $1000-$1500 price range though, I’ve found the Zipp 303 S and the Bontrager Pro 37 have the best combination of performance and that’s why I recommend them. In this value-carbon range, the Zipp 303 S is a + for versatility, stiffness, handling, climbing, and acceleration and on par with the average value-carbon wheelset for aero speed, crosswind management, and comfort. All those plusses with no negatives are about as good as you can find for this price. Steve

        • I have the 303 Firecrest and the 454 both tubeless. Running 28mm on both currently. I appreciate the information about the 303 S set. I am also a 70.5 kg rider. Probably don’t quite make the heavier range you were mentioning. Will warn though on the Firecrest set check your spoke tension. Found the wheels were no where near proper tension from factory. A few on disc side were reading 0 to 3 kgf never touching the wheel accept to unbox it. Had to do a bit of work. Was semi upsetting considering the cost and the quality would expect from zipp. Might try the 303 S as a backup set for training.

  • Hi Steve.
    What in your opinion after riding both is the better Wheelset – Zipp 302 or Zipp 303s? I could pick some 302 up for £850 – or is it worth the extra £ for 303s.

    • Mark, Very different wheelsets. Your choice would depend on what performance attributes you are looking for, what kind of tires you are willing to use, whether you need rim or disc brake wheels, and what kind of terrain you want to ride. Would suggest you read the review of the 302 and other value-carbon wheels in my review here. Steve

  • Excellent articles and glad I found your website!
    Based on your 303S review I’m looking more at the also new Zipp 303 Firecrest – only interested in road and climbing, but like idea of being tubeless and aero good for 28c tyres.
    Any plans to review these anytime soon or any thoughts?

  • Thx for all you reviews.
    I have read that Zipp purports that their tubeless tires can be put on these wheels without using a tire lever and a floor pump will suffice. Did you find that to be accurate?

    • Danny, Yes, the Zipp Tangente RT tires I tested went on, inflated, sealed (and came off) rather easily. Steve

  • Just curious why your review says the 303s is faster with a 25mm tire and Zipp says 28mm is faster on these wheels? Also, I know that Zipp says all tubeless or tubeless ready unless a tire company says no hookless tires. I know that the continental 5000 tl say no hookless rims but what are your thoughts. I’m guessing no way but man I love the continentals and I’m considering the Zipps. Thank you Max

    • Max, Zipp’s new approach to speed looks at how fast you go for a given amount of power expended and is based on four factors – aero drag, rolling resistance, wheelset weight, and road conditions. For me, that’s too many variables that aren’t all in play to the same degree at different speeds and road conditions.

      For example, aero drag affects your speed far more the faster you go (it’s logarithmic) while rolling resistance has the same effect at whatever speed (it’s linear). After exceeding about 15 mph the importance of aero drag outweighs rolling resistance and as you get faster it can be more important by a factor of 2 to 4x. Wheelset weight only matters under acceleration, and then no more than aero drag, and when you do long, steady climbs in excess of about 7%. Road conditions are also variable but on most decently paved roads, there’s little difference in their effect compared to aero drag. Zipp’s new way of measuring speed (called Total System Efficiency) is a hash of considerations that perhaps applies to a wheelset like the new 303 Firecrest that you’ll ride on the road and gravel but doesn’t work well in my view on the road. On gravel, you are doing most of your riding either side of that 15mph range, doing a lot of often steep climbing and the surfaces can be rather rough. So yeah, in those conditions, you’re better off with a 28C tire if you are riding on a dirt road or course and wider still (up to 40mm) if you are riding actual gravel.

      For road riding where I think the 303 S performs best and for any wheelset including the 303 Firecrest, I’m looking principally at aero drag when it comes to speed. From that perspective, a 28C tire that is wider than the rim is not going to keep the air flowing from it to the rim (and vice versa) in a smooth (laminar) way while a 25C that is narrower than the rim is going to get that aero effect and benefit. You’ll see the claim that a 28C tire also has better rolling resistance than a 25C, but that statement is only true when you add “at the same pressure”. Of course you put a wider tire on your wheels so you can lower the pressure and ride more comfortably. At 5-10 psi lower pressures, the rolling resistance for a 28C tire is much the same as a 25C. And again, rolling resistance is far less important when you are riding at road speeds.

      As to tires, I found the Schwalbe mentioned in the post above to be slightly more aero than the Zipp. And if Conti and ENVE say no to using the Conti GP5KTL on hookless rims, I’m not going to do it. They’ve both done the testing. If they’ve done any, I’ve not seen Zipp publish any testing. Steve

      • Steve,
        Thank you, I appreciate the information and clarification. This is tough one for me. I ride everything, gravel and road. I still love to road race but those races are only 4 or 5 times a year. Maybe the solution is to just put on 25’s during road race season. Again, thank you Steve, you’re site is excellent.

  • Steve,
    Great article, spot on!!!!
    (Sorry its a bit long…)
    So first thank you for making some “order” for me, with all that new wheelsets information out there coming from all the manufacturers this year, I think it’s a big change that major brands start to come out with decent carbon Aero sets in reasonable (sub 1.4k) prices, still way to go there but its a good direction.
    For me as I am new to road cycling, it’s nice to see that the tubeless concept is starting to get momentum, as an MTB hard XC rider for the past 14 years I truly don’t understand why the road category is so conservative to great ideas from other fields….it works perfect off road, lots of advantages (IMHO) and not as risky as tubular…in my local bike shop they still insist tubes are the best…go figure.
    Now, as I recently moved to road from MTB and now training for an Olympic distance triathlon, I chose to ride a 2020 Trek Madone SL6 Disc and I can say the that although the bike is overall a superb bike for me (tested quite a few) I totally don’t like the wheels…
    I am seriously considering replacing them after only 3 months of use, and currently the best candidates are the Bontrager 37 pro, Zipp 303S, JRA Mahi Mahi, and maybe the HUNT 44 AERODYNAMICIST CARBON DISC…
    So my main use is road and Tri on the Madone.
    A typical volume weekend training session is 80-100 Km , on an average 30 Kph speed on a 900 meter average climbing per ride.
    Which of the set would you recommend for my purpose? (I weight around 64 kilos – no issue there).
    Would highly appreciate you advise!

  • Hey Steve, thanks for the thorough review – it’s great having this out in the wild on such a new product.

    While your spreadsheets and reviews are great comparing top tier and budget wheels amongst their respective categories, it’s tough comparing across the two. With that said, I’m wondering how you’d size the 303S’s against Reynolds 46s?

    • Shawn, Depends what you’re looking for from a wheelset. My reviews of each try to give you their essence. Steve

  • I love the thoroughness and depth of your reviews, yet you communicate it clearly enough that a layman such as myself can understand it.

    Will be looking for 50-60mm disc wheels soon, as the stock ones on the Domane SL6 are, well, stock. I’m moving from a rim-brake cervelo S3 with D-A C50 wheels, which was super responsive. I know the Domane is a different beast, though I’m sure I can find wheels that will energize the ride.

    The question is: should I even be looking at “value carbon”?

    At 6’2″ x 225 lbs, I pay close attention to stiffness and reliability. Reliability, for me, means super low maintenance. I had the D-A C50s trued maybe once every 2 or 3 years (Not neglect, I had them looked at as soon as I saw or felt a wobble – those things are built to last).

    I’m hoping Tubeless lives up to its promise.

    Thanks mate, and again, cheers on the quality and consistency of your content.

    • Bernard, thanks for your feedback. Stiffness depends more on the wheelset than whether it’s a “value carbon” or “performance carbon” one. As the category name suggests, performance carbon wheelsets generally perform better on other performance criteria including aero and crosswind performance in the mid and aero depth range.

      I’ve not tested for reliability per set but performance carbon wheels generally come with better warranties and better service networks than value carbon ones. They often though not always have better, longer-lasting, more expensive hubs which is important to reliability.

      We’re about a few weeks away from posting a whole group of new reviews on aero depth (55-65mm) performance wheels for road disc bikes. There is also a regularly updated review of about 10 all-around depth (40-50mm) road disc wheels up on the site now.


  • Hi Steve,

    Love your site. Great reviews, very informative and thorough.
    I’ve learned the 105% rule on your site but I’m curious about the speed penalty that one gets by breaking that rule. Say for instance a rider with your profile mounts 28mm tires on these Zipp 303S, rides ~30km/h on rolling terrain for a 100km ride with 600m D+.
    Wondering how significant the penalty is. In my mind at some point, if the ride is long enough, comfort becomes more important than losing a couple of second/km here and there.


    • Eric, Thanks for your kind feedback. I’m actually polishing off research and testing on the effects of this rule that I’ll publish in about 10 days. Long story short, it really depends on your rim-tire combination, speed, and distance. Riding 28mm tires on all but the widest road rims including the 303 S, you essentially wipe out any aero benefit of having a deeper rim. The faster and shorter you go, the fewer seconds you’ll lose but the more important they’ll probably be to you. The slower and longer you go (while still riding at 18-20mph or better), the more time you’ll lose but the less you may care. It could be a matter of a few seconds for a TT length ride to several minutes for a 100-mile long ride. The most important thing is to pick the right inflation pressure with whatever tire you choose, albeit better with one that meets the 105% rule at that pressure. Doing so will also maximize your comfort and handling performance. Steve

  • Will you be reviewing the new Zipp 302 tubeless? Sorry if this has been asked.

  • Hi Steve, thanks for the thorough review.

    Do you know if end caps for different fork/frame combos (specifically QR) are included in the box, or do these need to be found separately somewhere?

    I’ve searched the end cap compatibility chart and have part numbers (looks like kits 11.2018.045.000 front and 11.2018.045.010 rear), but don’t see much availability from the online retailers.


    • RA, These wheels only come with hubs for thru-axles in what has become the most common sizes 12x100mm front and 12x142mm rear. Steve

  • First of all, thanks for the great work you are doing with your site. Helps a lot, especially for someone who is new to the sport.
    So pardon my newbie question, as I just got into cycling this year. I am looking to upgrade my stock wheels and these should be a more than enough of the upgrade for me, with one caveat. I would use the wheels for climbing quite enough and I read in one other review that one of the weaker point for these was in the freehub pickup (less engagement points, 3-pawl, 32-tooth ratchet setup). The reviewer explained that this would be noticeable during climbs. Since I am a newbie, I doubt I will have issues with it immediately but probably would somewhere down the road. Question is – can the hubs be upgraded better ones, should I want too later on?

  • I am considering either Zipp 303s or Hunt 50 Aero Disc. Which one will be a better or faster wheel?

  • Would the new Schwalbe Pro One tubeless” Souplesse” 25C improve the aero abilities of the Zipp 303 S due to its actual size being closer to its specified size ?

    • Perhaps but you’d be giving up comfort and handling in a wheelset that isn’t designed to compete on aero performance in the first place

  • Steve, I’ve been trying to upgrade to something newer and wider that the 2015 202″s I’ve been riding. I’m hoping the wider rim will allow the 28’s I’ve been riding to help relieve some of the road vibrations that plaque my arthritic hands. The problem is I’m still a rim brake clincher guy and am looking for a suggestion that fit the profile the 303’s or where to find 303’s that work for me.

    • Craig, A couple of suggestions from costing you nothing to a lot. First, 28mm tires and a better understanding of tire pressure effect on fatiguing a rider’s body has pushed pressure norms way down. So try lowering the tire pressure on the 202s you have by 5 psi each time you go out until they start to feel mushy in the handling. Then bring them up to the pressure you had on the prior ride. I wouldn’t corner the 28s very hard or fast on those rims as you’re more likely to get a pinch flat from a tire folding up on itself due to all the tire overhanging the rim. You’d be better off with 25s on those rims at lower pressure than continuing with 28s.

      As far as new wheels, the widest rim brake wheels I’ve seen are made by Bontrager. The Aeolus XXX4 that I reviewed here is a great wheelset, similar depth to the 303 NSW rim brake wheels I also rate highly in the review but 21mm internal vs 19mm for the Zipp and most modern rim brake wheels nowadays. You could put a 25mm or 28mm on either to get good handling though the 25s will give you better aero performance. Both are comfortable with the 25s on them at the right pressures.

      And, if you feel you’ve gotten your money’s worth out of the bike you have now and can swing it for a new one, consider putting money into a hydraulic disc brake bike rather than spending a couple grand on a new set of wheels. Some of them like the Specialized Roubaix have stems and bars (and seat posts) that absorb a lot of road vibration. You can get 25C wheels to give you even more comfort AND the hydraulic braking will be better on your hands than mechanical rim brake levers. And if you’ve got the stomach for it, electronic shifting is also easier on your hands than mechanical ones. Unless it’s a hookless rim like the 303 S, you don’t have to run them tubeless though doing so would give you even more comfort. Steve

      • Steve,
        Great advice. Thank you The Bontrager’s are a pair I’m looking at, thanks. Not sure about a new bike becuase of neck issues which was taken into consideration when I had my Seven built for me and I’m not sure a newer bike can take that into. account.
        Thanks again for the advice, very much appreciated.

  • Hi Steve,

    Thank you for your response to my inquiry. Would the Zipp 303 S be a strong road/pavement option for the latest generation carbon frame endurance bikes such as a Cannondale Synapse or Giant Defy given the ride dynamics of these frames?

    • Pablo, Those two are endurance bikes, not racing ones and the 303 S isn’t a racing wheel so they have that in common. Beyond that, there are too many variables about your riding profile, goals, preferences, etc. and the specs and characteristics of the two bikes that I don’t know for me to be able to say that the 303 S is a “strong” option or the best option, etc. for your situation. I do my best to tell you how the wheels perform and their characteristics. I’ll leave it to you and what you know about yourself and your bike to take it from there. Steve

  • Hi Steve,

    Yes, upon reflection the answer is more complicated than question would suggest. The performance road bike segment I alluded could be be described as “endurance race”. I ride exclusively on pavement which in some cases is in less than ideal condition i.e. cracks, potholes etc. The speeds I typically ride are 17-19 mph where and when possible.. I’ve done several reads of your evaluation of both new Zipp 303 wheelsets and come away impressed with your understanding of their intended usage model. I think this endurance race segment places less emphasis on aero and more on comfort and durability at speed given the challenging conditions. Of course any aero advantage is always welcome but not a priority. In particular I look to wheels which are responsive and provide a measure of comfort. I look forward to your evaluations of the range of tires most suitable for these wheels.

    Again thank you for response.

    • Pablo, Zipp has published this list of tires compatible with their hookless rims which are currently the 303 S and 303 Firecrest disc. You can find my review of tubeless tires that compares some on the Zipp list here. Finally, just so we’re speaking the same language, there isn’t an “endurance race” bike category that I’m aware of. This post details the geometry differences between endurance, race, aero, and gravel bikes. You’ll find the Synapse and Defy in the endurance bike category which, as you say, puts a priority on comfort based on its more upright geometry. Steve

    • Pablo, an endurance bike is not a race bike. There is no “endurance race” type of bike. If you want to gain more comfort to accommodate potholes and cracks in the road, then simply increasing your tire size to a 32 or larger (assuming your bike can handle it) will improve comfort more than any carbon wheel upgrade. You could also go tubeless which would allow you to run your tires at a lower pressure which will also help absorb bumps on the road.

  • Wilson, Endurance Race refers to endurance bikes which are designed for a more up tempo pace than is typical of the genre. On the UCI World Tour calendar every year there are a series of one day races in the spring known as the “Cobbled Classics”. Paris-Roubaix and The Tour of Flanders are the prominent examples. These races have large segments ridden over cobblestone roads some of which are ancient. In recent times bikes like the Cannondale Synapse Carbon Hi Mod and Specialized S-Works Roubaix are utilized in these races to feature technology consumers may find appealing for their road smoothing design elements. In 2018 Peter Sagan, 3 times World Champion road race won Paris-Roubaix aboard a Specialized S-Works Roubaix featuring a “Future Shock” fork suspension, most definitely an endurance bike design element. This segment of the performance road bike market it seems has a cross over appeal and a potential for greatly expanded sales by manufacturers because of these comfort related features. Component manufacturers such as Zipp and tire manufacturers seemingly are following suit.

  • Hi Steve,

    Thanks for your amazing reviews, I always enjoy to read them! I am considering to buy either the zipp 303s or the mavic cosmic sl 45 disc, since they are both in my price region. Do you hvae any experience with this mavic wheelset and how it performs compared to the zipp 303s? what would be the better choise concearning aerodynamics and stiffness?
    Thanks in advance!

  • Hi. Thanks for the review. Have you get the chance to try the Parcours Rondo or Parcours Strade? Looks like great contenders to the title…

  • Thanks for the detailed review! I picked up a pair of 303s earlier this year, and have been enjoying them.

    With more and more officially hookless-compatible road tires coming out, there seems to be a trend of not recommending 25c tires with 23mm internal hookless rims:

    1. New Conti GP 5000 S TR: “ETRTO-2021 for 25-622 on 23TSS not approved by Continental”
    2. 2020 Schwalbe Pro One TLE: “tire/rim combination not recommended”
    3. Pirelli P Zero Race TLR: “TLR 26-622 [and TLR 24-622] are NOT compatible with hookless rims”
    4. Enve SES: “Inflating Width [of 25c on] 23mm Internal = N/A”

    What do you make of this?


    • (Note, I’ve edited this response a day after I first posted it to provide more clarity, or hopefully more clarity than my first attempt even though it’s longer!)
      Ryan, there are a few things going on here.
      1) Tire companies are conservative for their legal protection. Their recommendations follow ETRTO standards, a standards body that many of the tire companies contribute to.

      2) ETRTO standards are always conservative – we’d never ride a 25mm tire even on 19c or 21c internal width rims if we followed the ETRTO in the past which were based on 15mm rims. Now 19c rims are the basis for their latest 2019 recommendations and 25c tires are approved on both 19c and 21c rims be they hooked or hookless.

      3) ETRTO does their testing at “maximum tire pressure.” Yet for some tubeless tires, the maximum tire pressure marked on the tire is often far higher than we’d ever inflate them to these days (e.g. 115psi) and even the minimum marked pressure (e.g. 80psi) on is higher than the maximum pressure indicated on the rim (e.g. 74psi). And to reduce the scary factor here, the better wheelsets don’t blow off tires or destroy the rims until well above the max rim and tire pressures, starting somewhere around 150psi.

      4) New ETRTO standards have tire companies making new tires (and recommendations), most of which are a size up for the stated width of the prior modes but measure closer to the stated width on the new models and what the actual width was on the prior models. For example, former 25mm tires are often now sold as 28mm but still measure what the former 25mm tires used to measure on 19c and 21c rims which was closer to 28mm than 25mm. Bottom line, the stated width and measured width are closer now than they were before. So that’s good.

      5) Wheelset makers with hookless rims like Zipp and Enve describe their rims by their actual internal rim width (like 23mm) rather than using the “C” designation used by ETRTO. That’s more helpful to cyclists like us but confusing when looking at ETRTO standards which put hooked and hookless rims under the same “C” designation. Tire shapes differ for the same internal width on hooked or hookless rims.

      6) Bottom line, there’s a lot of transition going on now. You’ve got some tires that conform and others that don’t to the ETRTO standards. Some are compatible with hookless rims and some aren’t. ETRTO also recommended new rim standards to work with the new tire standards. Some rims do, some don’t and probably fewer rims meet the new standard than do the tires. And that results in some tires still installing easier than others.

      And there’s some confusion within tire companies about what to say or even what they are saying. On one Schwalbe website page (here), they say 25mm tires are not recommended with 23C hooked or hookless rims. On another (here), they show that it is fine.

      So you need to look at these on a case by case basis in considering what tire to use with what wheelset/rim. I’ve done a ton of that in my tubeless tire review and will update it when I get the new Conti tires and others that look to be competitive performers. Tire companies that are big into ETRTO like Schwalbe are putting that out as their guidance. Some wheelset companies like SRAM/Zipp are saying use the tires that the tire companies have told them are compatible with their wheels. For those, you are going to get a conservative recommendation like they don’t recommend using 25mm tires with 23C hooked or hookless rims. ENVE does a better job in telling you which tires work with each of their wheelset lines and recommend tire pressures based on your weight.

      But, for example, the 303 S actually only has a 22.5 mm inside rim width by my measurement and I’d never inflate a tire to maximum tire pressure (as ETRTO does) for my 150lb/65kg weight. And the two 25mm tires I tested on it (the Zipp Tangente RT that was used in the development and testing of the wheelset and was made to the prior ETRTO standard and Zipp no longer makes, and the Schwalbe Pro One TLE that conforms to the new standard) handled well and were more aero yet less comfortable than the 28mm versions of the same tires.

      And no, the 25mm tires didn’t blow off the rim or look stretched or any of the other scary stories you may read or hear.

      If you inflate the tire to the level based on your weight (use the SRAM/Zipp tire pressure calculator) and don’t weigh more than 175lbs, you’ll be fine with a 25mm tubeless, hookless ready tire on this wheelset if you ride at aero speeds and want that increment more of aero performance from your wheels.

      For example, using the tire pressure calculator for a 175lb/80kg rider with a 20lb bike riding on the road on wheels with a 23mm hookless inner rim width and 25mm labeled standard road tires on a dry road, it recommends 67psi front and 72psi rear tire pressure. Beyond that weight the calculator will tell you that suggested tire pressure exceeds the rim pressure rating. In that case, a 26mm labeled tire will give you 65/69psi front/rear recommendation and a 28mm labeled tire will recommend 60/63psi.

      FWIW, I find the Zipp calculator always recommends a 3-5psi higher pressure reading than what I find comfortable.

      If you favor comfort, go with the 28mm or lower your tire pressure.

      Thanks for your good question. It forced me to go through this. Steve

      • Hi Steve!

        Does this mean that I shouldn’t run a 25mm Schwalbe Pro One TLE on the new Zipp 454 NSW Disc Tubeless? I was under the impression I could run that combo. Thanks, —kellen

        • Kellen, take a look at my revised response to Ryan above. In short, if you’re under 175 lbs or don’t inflate your tires above 75psi, you can run that tire with those wheels without issue. Miles, Nate and I have been doing that with good success. Steve

      • Hi Steve, thanks for your thorough explanation! I just wanted to order a set of NSW545’s together with the new gp5000str 25mm tyres. Since zipp advises 25mm tyres on their wheels and continental just made a hookless compatibel tyre, I was sure that both would be compatible. But now, I see on the continental website ánd on the zipp website that the combination is not advised?! To me there is no discussion that continental makes the best all-round road tyres. I would really feel foolish to buy nsw wheels but not being able to run the contis or to have to run too wide contis which lose the aero advantage. If I read your reply above, you would still advise to try the continental tyres on the 23mm NSW rim?

        • Michiel. Please re-read my comments. I didn’t advise using the Conti 5000S TR tires as I haven’t tested them so can’t say. My comments relate to rims and tires in general and our experience with Schwalbe Pro One TLE tires on the 454 NSW rims. Steve

      • Great info! Most appreciated.

      • Hi Steve! I just purchased a set of Zipp 404 2022. I also purchased the Pirelli P ZERO Race TLR 700x26C as they work with the pressures I need per the Zipp calculator. I am 6’4/88 kg so I want to go as wide as I can, yet be within the 105% rule. These hit the sweet spot. Pirelli says no to 26 on hookless on their website but Zipp just says “Pirelli” and doesn’t exclude the 26mm like they do for the GP 5000 S TR. Am I crazy or smart to ride 26mm front and back at approx 70psi? I mean the Specialized does not exclude the S-Works turbo from hookless rims at 26mm on their website. Any reason why the Pirelli wouldn’t work? If you can give your 2 cents I would be so happy! Thanks!

        • Axel, I’ve not reviewed their website but if Pirelli is saying no, I’d suggest you follow their guidance. Steve

          • Thanks Steve! Well at my weight, I have to run 28s. Would I be better of getting a pair of 4.5 ARs or Rapide CLX instead? I guess 404s are only for light riders? Hopefully someone else can learn from this!

            Any idea of how much is lost from running 28s on zipp 404? I have emailed zipp but haven’t received a reponse yet. Big thanks!

          • Axel, You’ll be fine, maybe better off with the 28s unless you’re racing on smooth roads. I’ve got a post going up next week about this that will say more. Steve

          • Awesome, thanks Steve! Also just received this email from Zipp’s customer service, very encouraging!

            “Hi Axel,

            Thanks for your email.

            Let me help with your tire questions.

            Although a 25mm tire may be more aero in the wind tunnel, a 28mm tire for road riding and racing is the ideal tire size at the appropriate pressure ( It’s important to note that hookless rims behave differently than hooked rims, and the 105% rule is not applicable. Thanks to hookless, the transition between rim and tire is seamless, already providing an aero benefit vs. standard rims. This also means that the rim/tire ratio can be lower than 105% without performance loss.

            Through Rolling Road and Real Life testing, we’ve found that rolling resistance gains with a 28mm tire far offset any loss of aerodynamic efficiency.

            In fact, we’re recommending our professional riders and teams to race on 28 or larger tires for the 2022 season.

            On Zipp wheels, a 28mm tire is faster than anything narrower.”

  • Thanks for your revised response Steve! I skimmed your original yesterday and still had some questions. The additional detail cleared it up 🙂

    For what it’s worth, I’m currently running 25mm Schwalbe Pro One TLEs (2020 model I believe, with the orange logo) and they measure just over 27mm on the 303S at about 55psi. I’m a small guy (120 lb/55 kg) and run pressures in the mid-50s based on the Zipp calculator. Happy I can keep running this combination.

  • This is such a great explanation. Wow, thanks again for the updated reply and insight.

  • Hey steve

    Did you ever compared the roval 38 vs the aeolus pro 37 and the zipp 303?
    because these are the wheels on my shortlist. How do we comare because i think that they are all so close.
    Or what do you prefer. I’m a typical belgium rides who rides flanders classis to liege bastenaken liege.


Leave a Reply

Your email address will not be published. Required fields are marked *