Hookless confusion? Just me?

I just posted this in the comments from the tech mailbag, but thought I would put it here as well.

I am sure someone will just say run tubes, but as a mtn biker as well I have been running tubeless for years and it is great, so thought I would test it out now that things seem to have gotten a little better on the road side?

Here is my post:

Late to this article, but I have been trying to figure out what to do since I am getting a set of wheels with 22/27 dimensions and would like to run a 25c tire up front for aero purposes.

It seems that no one in this industry has any idea what is going on with their products:

ENVE lists the same pressure for you (other poster) at 63psi for 130lb rider on 25c tires with 21 ID rims, but lets look at where it just gets bonkers:

They claim a max of 80psi for their AR wheels which is above the ETRTO limits for hookless. However for a 250lb rider with a 28c-30c tire only needs 67psi according to them. Phew.

They say that a 160-170lb rider (me) needs to run 75-79psi for a 25c tire on a 21 ID rim, again above the ETRTO recs. 25-26c tires would be the correct tire for aero for the Foundation series, which is again hookless and 28mm external diameter. In order to meet ETRTO psi specs you would probably need to run a 28c on the wheels and therefor not aero optimized. (Yes I know they have their own 27c tire, but limited choices and also not aero).

So their aero recommended tire of 25c is out of spec for anyone over the weight of 155lbs and running a 28c reduces the whole point of the aero wheels by not being aero optimized.

So lets head over to Zipp:

According to a reputable website: New Zipp 303-S aero wheels are wider, hookless, tubeless, cheaper, disc-only - CyclingTips

The 303s are hookless and therefor follow the ETRTO limits of 73 psi. They claim that riders up to 253lbs can run 25c tires without going above 73psi.

Why am I focusing on 25c tires? Because again these are aero wheels and the 303s are 27mm external meaning they need a 25c tire to have the best aero performance. They also list 25c tires on their chart even though having a 23mm ID is supposedly too wide (according to ETRTO) to safely run 25c tires on hookless rims.

But wait there is more, enter Schwalbe:

Their chart claims that 25c is recommended by them to be on 22-23mm ID rims and they even point out they are going beyond the ETRTO recs.

Lastly why did I mention my wheels in the beginning? Because as noted above I am getting wheels that are 22/27 which means I will need to run a 25c tire for aero gains. But according to Continental (I would like to run GP 5000 S TR) they only recommend 25c up to 21mm ID and 28 for 23mm ID. ETRTO also is in line with that.

So do I follow ETRTO (and Conti) who have been notoriously conservative? Or do I go with Schwalbe and Zipp who seem to say 25 is all good on >21 ID rims?

I am confused, the tire makers seem to be confused, the rim makers seem to be confused, the ETRTO seems confused, are you confused yet?


You don’t want to hear it but your answer is just run tubes.

The reality is that tubeless is awesome on mountain bikes and gravel bikes because it works really well at low pressures. At the much higher pressures found on skinny tires, it doesn’t make sense unless you’re fairly lightweight. At 170lb rider, 190-200lb total weight of rider and bike and kit, I’d say just put some good latex tubes in your tires, throw 85psi or so in, and go ride your bike… just because it works great in your mountain bike doesn’t mean you have to use it on your road bike too.


No, it’s not just you :slight_smile:

This Veloflex article provides a useful summary of the 2022 ETRTO standards manual for road tubeless: Which tire size to choose for your road bike rims - Veloflex Blog. As you can see, 25mm tyres are approved for use on 23mm internal rims, although, personally, I would avoid running a hookless tyre at lower pressures than the tyre manufacturer’s minimum pressure spec. (which would rule out many, if not most, 25mm tyres). IIRC, Pirelli’s 24mm and 26mm road tubeless offerings are not approved for use with hookless rims (none of its Cinturato tyres are approved). Goodyear does not recommend using its 25mm Eagle F1 tubeless tyre on hookless rims with internal widths greater than 22mm: Eagle F1 - Goodyear Bike

I recall reading or hearing an interview with Bastian Donze from Zipp in which he said that based on their testing, hookless and hooked tubeless tyres blow off rims at around the same pressure and that hookless rims can safely be run at pressures far higher than the ETRTO guidelines. His expectation is that the ETRTO max pressure guidelines will eventually be revised upwards, but for now, you exceed these at your own risk.

For what it’s worth, after much experimenting, I’m currently running 28mm Pirelli P Zero TLRs at 58/62 psi on my Zipp 303FC. I’m ~190lbs.

I hope I haven’t added to your confusion.


That’s exactly my experience.

I am a mountainbiker and love my tubeless setup there (actually installed CushCore yesterday, let’s see about that).
So I thought I’d upgrade my road bike with a nice set of tubeless carbon wheels. Got myself the Zipp 303S with the Schwalbe Pro One 28s (this seems to be the tire everyone is riding with this rim, since the Contis aren’t really available yet).

According to the Sram calculator, I should run around 4.7bar/68psi. So I did.
Had a flat two weeks ago for the first time (pretty big hole that the sealant couldn’t fix) and took the tire off. Turns out my rear rim is clearly damaged in several spots.

I know I am on the heavier side, but I followed the manufacturers recommendations and I really don’t think this should happen. According to the Zipp website this should be replaced by warranty. I’m still disappointed.
Conclusion for me; Run tubes on my road bike. So I’m on my good old alu-rims again, and will probably sell the Zipps once they get replaced…

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Stuff like this just seems to confirm to me that hookless rims for road tubeless just isn’t there yet and for the rider it’s a solution still looking for a problem.

The main benefits it appears to me are for the manufacturer.



Thank you for that article which I think outlines another issue. If I remember correctly you cannot access the ETRTO recommendations unless you pay for it. So the consumer has to rely on the tire/wheel companies to publish the findings. Look on the web and there are numerous outdated ERTRO recommendations. This is a safety issue and should not be up to the consumer to figure out.

It is good to see that the ETRTO has updated the combos and that 25c is good to go for up to a 23 IW rim.


I think there is a little miscommunication going on. I think road tubeless works well enough, well enough for me to try out. There are plenty of people that have been running road tubeless for a while with very little issue. It is pretty much running the same course as mtb. No standards and poor fitting rim/tire combos. If everyone just continued to put a tube in it, then mtb tubeless would have taken longer to come around.

My issue is more of the confusing presentation by all the parties involved. We have already done this before so why do we keep making the same mistakes.

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Are those chips from rim strike after you punctured? Did the bead unseat?

I’ve damaged several carbon rims running tubes after sidewall blowouts, so this sort of damage is not exclusive to hookless rims or road tubeless generally.

I hope you get this sorted under warranty. :+1:


Agreed - are there any direct consumer benefits? I guess price is one, but that it is from what I have heard.

Lighter weight, stronger rims, less likely to pinch flat/tire protection


The flat was a big hole in the middle of the tire tread. These marks in my photos are in several spots on the rear wheel.
You are right that this doesn’t only apply to hookless rims, but basically all tubeless carbon wheels.

The 303S are advertised for road and gravel, and I’m wonderinng if they just shouldn’t be used with a tire as narrow as my 28s.
I feel like the rim would have been better protected with a wide gravel tire, even when using less pressure.

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I think you’re right and that’s definitely one of my chief concerns with my Zipp 303 Firecrests, which are 25mm internal and also promoted by Zipp as being suitable for gravel. I’m running 28mm tyres at the moment and have wondered (read: feared) that rapid deflation due to a large cut could cause the bead to unseat and expose the rim to the sort of damage you’ve experienced. There’s always the option of running inserts, but the thought of trying to wrangle a tubeless tyre on with one of those is enough to deter me from using them.

I have a couple of sets of Bora WTOs and, fortunately, tubeless tyres have always stayed seated on those after sustaining large cuts. Maybe hooked tubeless rims are better at retaining tyres that suddenly and rapidly deflate.

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I also thought about a tire insert (because I just installed it on my MTB and I think I love it), but refuse to put that extra weight on my road bike, ruining any weight benefit from the carbon wheels in the first place.

If Sram/Zipp will refuse to exchange my rim in warranty, I’m actually gonna build up a Gravel Bike, and will use the wheels on there with an insert.
Though I would still prefer to have the wheels gone and my money back…

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What sealant were you using when this happened? This also seems to be an important factor when looking at the ability of tubeless to seal.

FWIW I got 1.3 cm gash in the middle of my tire with hookless 303 FCs and schwalbe pro one 28s and orange regular sealant that sealed.


I am not sure how your experience relate.

Regardless of the pressure you are running, regardless of the fact you are running tubeless or tubes, regardless of the nature of the rim, hooked or hookless, you can have a flat and the rim can be damaged by running flat before coming to a halt.

So I am not sure what is your point?

I’ve been so confused about this issue too. I’m planning to get the newer zipp 404 firecrest which also has an internal rim depth of 23mm and is optimized for 25/26c tires. I’ve had great experience with conti tires and was very disappointed to find that they don’t recommend running their 26c conti gp5000 s tr bc the internal width is greater than 23mm. My second choice of tire was gonna be the Pirelli P Zero Race TLR Road Tire but their 26c also are not approved hookless. Both the conti and pirelli p zero 28c tire wiIl work with these rims. I remember watching GCN video on the 404 firecrest and saw the presenter running 28c and said the rim to wall transition was still flush and didn’t bubble out. If that’s the case I may run 28c tires if the losses are minimal compared to a 26c tire, or until conti updates it’s recommendation

go the 28 pirelli, not sure what the downside would be? im sure you’re talking a watt, but the upside comfort surely makes up for it?

not being a contrarian but is this even a possible outcome? I have had many rapid flats on hookless rims and never an issue like what you describe, nor anything that looks close. i imagine these sorts of things could theoretically happen with tubes too no?

Thanks for putting my mind at ease :slight_smile: As I mention above, I have experienced this with tubed carbon clinchers. Never with tubeless. However, friends of mine who MTB have experienced this with hookless rims, some with concerning frequency. That may be best explained by the conditions in which they are used (or misused).

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I’ve recently bought a set of 404 FCs and have put 28mm P Zero TLRs on. Not ridden yet (covid/winter roads) but will have a look at the rim-tyre interface regarding aerodynamics. I’ll see if I can photograph it for you so you can make a more informed decision!

@Big_Watts i know it’s been a minute but how did those 28c pirellis go with the 404 firecrest? Any pics and measurements of actual tire width?