Hookless or not?

I am adjusting my tire pressure and only recently moved to Tubeless.

I ride Pirelli P Zero Race on Syncros Capital 1.0 50 (on Scott Foil 2020, if that matters) and trying to figure out if (1) my wheels are hookless or not to figure out (2) max pressure. (Silca’s calculator puts me over the 75 PSI max pressure for hookless). I will not be interested in undoing the system to look at the wheel from the inside.

Any way of figuring it out from the outside or based on wheel specs somewhere? and any advice on max pressure for tubeless?

I suspect they are hooked as none of the adverts or cached page for the 50mm version of your wheels says, whereas the newer aero 60’s boast hookless.


I think the max pressure is 72 psi, unless specified otherwise. I don’t know what the rationale was, but my recollection of a Cyclingtips podcast with someone from Zipp was that there is little safety margin built into that pressure recommendation, so I really would not want to exceed it.

This popped up on Weight Weenies the other day:’


The same forum user seems to be dedicated to posting about the issues of hookless :smirk:

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I’m not really anti-hooklesss but I do find the concept of “boasting” hookless a bit odd.

“We’ve made the wheels lighter and cheaper by removing a safety feature - yay us!”


No one ever had a blowout before hookless? :eyes:

My understanding is that hookless is really best for wider tyres. At least 28mm. That video features an Extralite rim with 25mm Conti GP5k S TR. That seems pretty narrow to me - Zipp don’t recommend that tyre in that size for any of their wheels, though are fine with the 28mm and larger versions. Extralite do publish a tyre compatibility manual for that wheel which lists the Conti GP5K S TR but doesn’t specify any particular widths which seems odd to me (they specify sizes for all other tyres). And the same manual also then talks about tape thickness and “tuning tape thickness” to ensure a tight enough fit for your specific tyre-rim combo. Personally that would ring alarm bells - “tight fit” seems quite subjective and introduces possibility of user error. I’d be much more comfortable with a wheel that arrives pre-taped from the manufacturer and with a full list of tested and approved tyres and sizes including specifically calling out tyres/sizes that have been tested and failed which in Zipp’s case would seem to include the 25mm Conti.

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I know N=1 isn’t science, but I’m probably one of the heavier guys on there at 210# and I’ve had no issues with hookless zipps on gp5k str at 73psi.

That said, it was always kinda on my mind, which I didn’t like. Those wheels have been converted to cx duty at about 26psi on challenge tires, so I’d say the blowout chance is hopefully limited. I say that bc it was damn near an act of congress to get those tires mounted. They do stretch a bit but I’d like to assume they’re gonna be equally a pain in the ass to get back off

Usually not at that tire pressure…

I’ve talked unofficially with industry peeps and they all said that hookless rims are easier and less expensive (has something to do with QC tolerances and the way they come out of the mold…not sure) to manufacture and one of the reasons you saw the earlier makers of these were the cheaper Chinese manufactures who adopted it adopted to the trend real quick.
I have both and have never had a tire on hookless rim blow on me but basic common sense does not make me feel warm and fuzzy about them. It can happen to hooked rims as well though, I was climbing a big, high altitude (14k) climb and the pressure increased so much it blew the tire with tube off the aluminum hooked rim, fortunately while climbing and not on the decent.

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Yup, way easier.

The same hook that keeps your tires on also prevents easy mold release in the factory.

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I will link the thread I started, but I blew my tire straight off my rim in June and we discussed it.

OK…LOL at running this “experiment” inside your house .

The recommendation for at least 28mm tires is based on the ETRTO specs for a rim that has a 25 mm internal width. These rims have a 21mm internal width, so a 25mm tire should have been OK.

But if you already have the tech to produce hooked rims, why advocate hookless because surely a lot of competitors will jump in producing cheap hookless rims

Not much tech, just more of a pain in the ass for the worker because more components need to be bolted and unbolted for each and every part. The savings is primarily in the labor.

Moldmaking for carbon fiber is the easiest type of moldmaking in the entire manufacturing industry because everything’s made of aluminum (easy to cut) with looser tolerances and surface finish requirements than say, a hardened steel injection mold that will be used to make millions of plastic parts.

That’s not to say there isn’t more cost of molds for the hooked rims, just that it’s not as significant as the labor savings.

Yup, OK according to ETRTO current standard. Just 25mm seems a borderline case to me and personally wouldn’t buy a hookless rim if I wanted to run that width. I’ve heard smarter and more informed people than me like Dan Empfield and Josh Poertner talk about having at least a 5mm difference between internal rim width and nominal tyre width, and also talk about this being a technology best suited to wider tyres. There’s rumours the ETRTO standard will change to having a max 23mm rim width for 28mm tyres ( Rumor: Upcoming ETRTO Spec to Limit Inner Rim Width to 23mm for 28mm Tires - Equipment - TrainerRoad) which would align with that 5mm difference and would imply that the max rim width for 25mm tyres might also get narrower.

Plus for most men 25mm isn’t a good choice on hookless as the optimal pressure for that width is likely to exceed the 72psi limit. e.g. just plugged 21mm hookless rim and thin 25mm tyre into the Zipp calculator and even for a 60kg rider the recommended pressure still exceeds 72.

Does probably reiterate what a bad job the bike industry as a whole is doing to make things easy for the consumer! Really shouldn’t be having to look up ETRTO charts or wondering whether you need to add another round of tape to get a tight enough fit that you’re not going to blow a tyre off halfway down a mountain.

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i’m running hookless tyres on my hookless giant rims. i race on them, train on them up to 70 psi. no issues. i’m assuming giant and continental have done their homework.


(Sorry…not a fan)

As for the substance of your post, no major disagreements from me…I think this is another case where the bike industry has gotten out in front of themselves and rushed to adopt new “standards” or technologies that work in one area and apply to them to others (in this case, taking hookless form MTB and trying to apply it to road).

It is then compounded by the Pavlovian need to have “more”…in this case, internal rim width. “Well if they have 23mm internal, we’ll do 25!!”


I don’t have any inside info to judge safety or not, but my big thing is:

Other than a claimed reduction in cost, I’ve seen no claims for benefits to the rider. It seems like the general selling point is “it costs less”, with more restrictions on safety margins.

  1. I just bought a pair of Light Bicycle hooked tubeless wheels for less than Zipp charges for the 303S

  2. As someone who recently had a carbon clincher rim brake fail on a descent, money<<<<<safety anyway. I’d happily pay more for additional security.

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