To be honest, when Zipp reached out to schedule a video chat about tubeless, hookless rims for road bikes, I wondered what was up their sleeve. After all, we’ve kinda covered hookless rim designs.

And they explained their design decisions when the latest 303 Firecrest wheels launched. ENVE gave us their thoughts on it, too. And we’ve seen designs from a number of brands pop up in the last couple of years, slowly giving credence to the idea that higher pressure road bike tires will, in fact, work just fine on hookless tubeless rims.

So, what’s new here?

Well, it’s a video interview for one, but there’ve also been updates to ETRTO and ISO standards that are bringing everyone closer to a level starting point. Which means safer Road Tubeless designs for all of us, and better cross compatibility between rims and tire brands. That’s a big part of our discussion with Bastien Donzé, Zipp’s wheel product manager.

Here are a few of the slides from our call:

What is a Hookless rim standard?

etrto hookless tubeless rim standards reference drawing for tubeless straight side rims

Above is a snapshot of the ETRTO reference drawings with measurements and tolerances for “Tubeless Straight Side” rims, more commonly known as “Hookless” rims. Click any image to enlarge.

closeup of etrto hookless tubeless rim standards reference drawing for tubeless straight side rims

Here’s the rim drawing portion enlarged. It’s worth noting that bicycles are basically the last type of transportation relying on wheels to use hooked rim designs. Cars, motorcycles, even airplanes, all use hookless rims. And all of those carry much higher weights under much higher loads and forces.

Word on the streets is that these measurements are basically approved by ISO, too, they just haven’t published them yet. Where ETRTO is technically a European standard (even though many companies in other countries adhere to it so that their goods are marketable in Europe), ISO is an international standard.

What tire pressure can I put on a hookless rim?

tire blowoff pressure chart showing burst pressure when tires are blown off of rims

This chart shows their “Burst Pressure” tests, illustrating how high the pressure has to be to blow a tire off of a hookless rim. Tire and rim measurements shown at top, and each point on the black line is a different tire.

They found only one outlier that blew off at a lower pressure…but for reference 10 Bar = 145psi. So, most tires held in place up to almost 200psi. Given that most rim brands are recommending lower tire pressures (Zipp has a recommended max of just 73psi on their new 303 Firecrest rims), you’re unlikely to ever blow a tire off the rim.

They provided their tire pressure recommendation chart with the launch of the 303 S wheels, which graphs rider weight versus tire width.

Which road bike tires are approved for hookless rims?

which road bike tires are approved for use on hookless rims

That’s the question Zipp gets the most: Which tires can you mount on hookless rims. And it’s one where their answer differs from some other wheel and rim brands.

Whereas some, like ENVE, are testing tires in house, Zipp’s sending rims to the tire brands and asking them to certify whether they’re approved or not. Which makes sense, because ultimately, it’s up to each brand to certify their own products, but here’s the caveat / good news:

As long as both parties are adhering to the ETRTO and, soon, the ISO standards, then all brands should work great with each other. In fact, Zipp says that if a tire is made to ETRTO Tubeless-Ready standards, then it should work just fine on their new hookless rims. If you’re in doubt, ask the tire brand if they’re up to standards.

Our take? Seems like there should be a little logo or hot patch that goes on rims and tires to indicate if they meet those standards, giving all us riders a quick, easy to understand visual confirmation that they’re made to work together.

After watching this, what do you think? Are you riding Road Tubeless on hookless rims already? Let us know in the comments!

Zipp.com

31 COMMENTS

  1. I’ve been waiting for the long-promised ETRTO/ISO standards to become actual standards. Once the tire and rim manufacturers roll out their next generation of compliant products it’ll be easier and safer for everyone who wants to try road tubeless.

  2. Have been riding the hookless Zipp 303S wheels for some weeks now, they work great. 60psi pressure on 25mm Schwalbe tires (measure around 27mm) works great for comfort and grip, roll very smooth. Very easy setup, they lock with a standard pump

  3. I’ve had a Rene Herse tubeless blow off an ENVE M50 at below the recommended max pressure (they also burped a lot). Rene Herse claims that ENVE has now tested and approved their tires with current rims but when I called ENVE last week to confirm (since they aren’t listed as approved on ENVE’s site), ENVE told me emphatically only what is on their site’s approved list.

    I hope these standards work out. I have 2xM525 and a set of 4.5AR and I really want to run a set of Rene Herse’s knobbies, as they ride fantastic, but I absolutely will not until I get a straight story. Schwalbe only. And forget road level pressures at this point.

    The industry may be last to arrive to hookless but the use case is different, but the industry is clearly teething. I will not put my life in jeopardy while they work it out. Next wheels are 3T’s new hooked gravel aero wheel.

    • I’ve had Rene Herse blow off rims too, fortunately just in the stand. Others have had them blow off while riding. RH deletes comments on their posts when people ask about it, so a lot of people are unaware of their safety issues.

      Same rims and other Panaracer options are no problem for me, but RH should just be left out of the conversation about tubeless at this point.

      • I’ve also had a Rene Herse (Barlow Pass) blow off a hookless rim while riding. I won’t use RH on hookless rims, whatever they claim about compatibility.

  4. Tubeless for gravel and MTB… sure… for road? STUPID. Have a flat that can’t be sealed and see how much mess and big a pain it is to get the tire back on with a tube.

  5. As a Non-lightweight rider, road hookless is an absolute no go. I am currently running hooked tubeless on my road bike, and it does improve the ride quality. Therefore I am willing to deal with potential issues with trying to put a tube in on the side of the road with sealant going everywhere. However going hookless, without that extra measure of the hook on the rim and tire to keep the tire on the rim is just not worth the extra risk, for ZERO gain for the rider. Let say a 100 kilo rider at 30kph hits a pothole/object in the path, that sudden impact is going to greatly increase the pressure, with the tire potential blowing off the rim, Now add into it lateral forces of rounding a curb, or a emergency maneuver, and the pressure spike required to blow the tire off the rim is much much less at exactly the point you need that tire the most. NO THANK YOU!
    It simply comes down to hookless is cheaper to make, and it’s not like the final product will get cheaper. The only real benefit is to the brand, at the expense of increased risk to all but the very light riders.

    • Zipp 303s is $1300 retail. Thats’s quite a bit cheaper than hooked Zipp 303 rim brake wheels from a few years ago. As for your other concerns, why do you think testing and standards are being implemented? Failure mode analysis…

      • Every time one of these articles comes out someone says they’re running 60psi with a 25mm tire. Are these 80lb riders or am I missing something? Tire pressure supports the rider, so I don’t see how that makes sense for average rider weights. You can’t just drop half your tire pressure simply because there’s no tube. You’d practically be riding on the rim, which for CX would be fine, but on the road that seems absolutely stupid.

      • First depends on the impact size and shape. Second you provide no basis for your assertion. Third, without independent well thought out data, opinions mean nothing. Fourth, one person’s small effect is another’s large effect. Those words in and of themselves mean nothing.

        • I guess if the impact covered the entire bottom third of the tyre volume and compressed the tyre consistently all the way to the rim then the pressure inside would go up nearly half way to the tested blow off pressure from the recommended maximum. That would be a somewhat large effect.

  6. I’d strongly advise people not to ride narrow tubeless tyre, narrow ID hookless rims. It’s asking for trouble. Big trouble.

    • IMO, 21mm internal width and 28mm tire is where tubeless start to make sense.
      25mm tire is also borderline worth it if the internal width is 23mm, which make the tire inflate to almost 30mm wide on the rim anyway.

      Just forget about 23c tubeless on rim that is 17mm or 19mm internal width.

  7. huck its more safe and rim printed w/0 silicon its possible to do too.
    zipp you dont ave tecnology sorry , and you push hucless only for solve your industrial problem.
    than we are not stupid 621,5 o 622 mm on D1 its natural

  8. And still ZERO benefit to the rider, but increased risk. As for X Zipp’s being cheaper than another X Zipp. SOOO WHAT??? That is simply competition pushing down the price of their overpriced wheels. As for “failure analysis”, no actual data is presented, and certainly not materials and methods, and certainly not independent testing. They can put out all the marketing drivel they want, but the fact remains, there are inherent problems with hookless and road pressures., and I certainly will not be putting my life/health on the line to give Zipp or anyone else a higher profit margin with hookless rimmed road wheels.

  9. Assume a tire is a torus with an inside diameter of 622mm and a a minor diameter of 28mm. Now to model an impact, I took a sector 35.1mm (1.5 inches) long as measured along the outside diameter of the torus, out of the tire, i.e. reduced that sector’s volume to zero. With a starting pressure of 85 psi, that “impact” would increase pressure to 86.5 psi. Taking a sector 63.5mm out, would result in an increase in pressure to 87.6 psi. Finally to get the pressure to go from 85psi to the lowest blow off pressures in Zipp’s chart, 145psi (10 bar) would require reducing the volume in the tire by 58.6%!

    The problem with an impact such as you suggest is NOT the increase in pressure. No the problem is the impulse delivered to the wheel/rim/tire and the resulting structural damage.

    Note all the math was done in meters and Pascals.

  10. My life is so much simpler since I gave up on tubeless and went back to using traditional road tires and tubes. It’s all just marketing hype to sell more product and may give the consumer marginal gains of time on the road but the significant losses of time in the workshop make it not worth the hassle. No thanks. Tires and tubes work great for me – rarely a problem and when there is it’s super-easy to find out why and sort it out quickly.

  11. I just want to chime in here as an actual user of these wheels. I have the new 303 Firecrest tubeless wheels set up with 28c Tangente Speed tubeless tires on my Scott Addict. They are fantastic. I have not had one problem with them in the five months I’ve had them. They’re comfortable on rough roads and stable on high speed descents. Give the technology an honest chance – it might convert you.

  12. I also use Zipp 303s wheels with Schwalbe pro one 28mm tyres set up tubeless on my Look 795 Blade. They are set to 55/60psi (I am 78kg) and are the fastest rolling tyre/wheel combo I have ever ridden (I know I cannot measure this but strava segment times and average speeds suggest so). So far I have ridden 3200km with no problems. As to unsealable holes in tubeless tyres, I have suffered these on gravel bikes and once on a road bike. To be honest the splits have been so severe a tube would not have worked either, a boot and tube was needed.

  13. I am 145lbs heavy and I use between 63-72psi on road tubed set-up 25c front and 28c rear tire. How is 63psi possible with 25c tubed set-up? It’s the wheel internal width. My rim has 23mm internal width. This rim make 25c measure closer to 29mm but has more straight and stable tire side wall than 28c on narrower rim.
    Zipp 303s has 23mm internal width, new Firecrest has 25mm so they can do the same, if not even lower pressure.

  14. assuming you get a flat. Running tubeless on my fully rigid mtb over the past 5 + years has only recived one slow leak flat on the trail. I image close to the same preformance on road with wider tires.

  15. Clearly you did not watch the video! There is a lot of data out there, you just need to search for it(look at mtb rims, it is the same tech, than compare a hook design). It is a fact that a hookless rim has a much stronger rim wall than one with a hook! there is more material and a higher wall.

  16. Hookless is absolutely pointless. It saves virtually no weight, it makes the rim edge weaker to impact and is easier to have a blowout. It requires a tighter seal of the tire which makes it harder/impossible to remove tires specially on the roadside. The only benefit to hookless is that the manufacturer pays less to make the rim molds. There is NOTHING in it for the customer. worse product for more money, that’s where this industry is going.

    • This is at least partly incorrect; hookless rim edges are stronger. This is why they are an increasingly popular choice for applications where pinch flatting would have previously been a concern.

    • I believe this is a good question. Because to get a good air seal and to possibly limit the risk of blow-off, the tyre bead profile should match the rim one. Is a tyre bead compliante enough to adapt to both types of rims ? I don’t have the answer …

  17. Agree with others here. Tubeless hookless road is a mess and a disaster waiting to happen. Only reason they are going for hookless is to save $$$. I can’t fathom paying 2-3k for a wheel set that only works with a few tire options. What happens when said tire is no longer manufactured, recalled, etc? Love bike technology but hookless is a hard no.

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