the value of this forum has never been us, or me. it’s been the wealth of expertise that volunteers its time and i specfically call out marcag as an example.
now, marcag and i don’t agree on the signal issue that animates tech discussions in road cycling today. but what interest is there in talking with people you agree with? that discussion lasts 30 seconds and then what?
when i wrote the “news” of zipp’s new disc on the front page this morning to me the news wasn’t the disc, it was the decision tree that led to the specs and design choices that inform this wheel. this is what i wrote and this is worth discussing. i think we see the limits of zipp’s ambitions for hookless. i think it has given up on 25c being a legitimate tire on a hookless wheel. i don’t know that CADEX and ENVE feel that way.
but as you know i don’t care, because i think 25c is a dead size now on the road. i would be unhappy if everyone thought that way, because where’s the fun in that? happily, i’m confident many or most people think i’m full of spit on this.
I have a question.
What was there first when designing hookless wheels.
The design and they, the manufacturers, found that the limit a tire stayed on safely was 5 bar max.
Or was the limit 5 bar rule already there and the design based on this existing rule of 5 bar?
I mean, is it technically not possible to create a hookless wheel that can hold a tire on at, lets say, 6 bar?
Why was it set on 5 bar at some point? Was this the result of testing after the design was finished and they found it couldn’t hold a tire safely beyond that pressure.
And started calculating optimal pressure to weight with that as a starting point?
I have a question.
What was there first when designing hookless wheels.
The design and they, the manufacturers, found that the limit a tire stayed on safely was 5 bar max.
Or was the limit 5 bar rule already there and the design based on this existing rule of 5 bar?
I mean, is it technically not possible to create a hookless wheel that can hold a tire on at, lets say, 6 bar?
Why was it set on 5 bar at some point? Was this the result of testing after the design was finished and they found it couldn’t hold a tire safely beyond that pressure.
And started calculating optimal pressure to weight with that as a starting point?
Jeroen
I’m guessing the process was “we can manufacture wheels quicker and cheaper by eliminating the hook”. And then they probably determined 5 bar was the safe max PSI. Zipp and Enve seem all in on hookless, and it does seem like the “technology” is safer at lower pressure’s, which wider tires will allow.
There are some ways you could increase the pressure but they all have trade offs, mostly about mounting the tire. A tire bead with less stretch would be one way to do that. You could also increase the actual diameter or the wheel, specifically the edge of the rim, or decrease the diameter of the bead. A potential way around this is to increase the diameter of the rim and increase the depth of the rim channel, which would give more slack for mounting. You can only go so far with this until the rim edge/tire interface is happening up the sidewall at a section of rubber not designed for that.
There’s also the added complication that the tire and rim manufacturers are usually different, so the margin for error needs to be greater. In theory if Zipp made hookless rims only for specific Zipp (or similarly known QC controlled) tires then the error margin could be lessened.
My guess is that a limitation of design was the ability to mount by hand, or at least with common plastic tire levers. That will fundamentally limit the psi unless there is something positively engaging the tire to provide extra holding force. Aka a hooked rim.
I’ve been avoiding tubeless (and disk brakes) because I just didn’t didn’t want the hassles. I was quite content with my HED wheels and 25mm tires with latex. But that all changed when I rode a bike with ENVE’s latest 3.4 wheels and 28mm tubeless tires at 60 PSI. No loss of speed and a limo-like ride.
I bought a new road bike almost on the spot because of how good the system felt.
My triathlon bike is a Felt IA with rim brakes and latex tubes. To make a meaningful upgrade, I would have to jump to a modern TT bike with disc brakes. I am not there yet, but I cannot deny the dramatically superior ride I would get with 28mm tubeless on the latest carbon wheels.
One thing is what the industry offers to buy and the other thing is what people ride nowadays. There’ll always be a lag of a couple of years, simply due to limited riders’ budgets (there’re other reasons like buyers’ hesitation / negative sentiment, that you seem to exaggerate). If only any new beautiful disc wasn’t costing us over 2’000 USD…
Preferred wheel and tire choice for road cycling isn’t the same as for triathlon nor TT. Triathlons & TTs are faster, often non-drafting and usually on better closed roads chosen specifically for a race. This makes the aerodynamic properties more important than rolling resistance, even more than in the same comparison for road cycling. Your preferred tire width for road bike might be 28/28 or 30/30 nowadays, but it’s probably 25/28 for a triathlon bike. Most triathlons are on the roads, so I don’t think 25mm is entirely dead, as it’s the most aerodynamic choice for 19-21 inner width wheel.
Would you care to share some bike count data from the last Kona and/or Nice? Or at least the pro bikes, please. We would clearly see how few of those pro riders rode anything more than 25mm in the front.
My triathlon bike is a Felt IA with rim brakes and latex tubes. To make a meaningful upgrade, I would have to jump to a modern TT bike with disc brakes. I am not there yet, but I cannot deny the dramatically superior ride I would get with 28mm tubeless on the latest carbon wheels.
I am no Marcag, but I think most of us already agree that 28mm is the sweet spot for the rear tire - my issue is the front wheel on a Tri, or even more specifically, a TT bike.
For example, the GCN video comparing tire width vs speed that concluded there is statistically no difference, but they had a max speed of 23.6mph - pretty slow even by my 77 year old standards. “https://www.youtube.com/watch?v=AK5KLvrzrb4”
Preferred wheel and tire choice for road cycling isn’t the same as for triathlon nor TT. Triathlons & TTs are faster, often non-drafting and usually on better closed roads chosen specifically for a race. This makes the aerodynamic properties more important than rolling resistance, even more than in the same comparison for road cycling. Your preferred tire width for road bike might be 28/28 or 30/30 nowadays, but it’s probably 25/28 for a triathlon bike. Most triathlons are on the roads, so I don’t think 25mm is entirely dead, as it’s the most aerodynamic choice for 19-21 inner width wheel.
“Road” is a wide range of terrain. Consider IM New Zealand’s rough chipseal, versus some other courses with smooth asphalt. There are plenty of courses where I’d happily go with the wider / lower pressure tires.
I bought a new road bike almost on the spot because of how good the system felt.
Yeah, I resisted for a long time. Until I tried 30mm tires on my road bike in my mountain-y terrain. The difference is not subtle.
It’s a problem for me. I used to spend around 50% of my time on my TT bike - which benefited me immensely when racing other roadies in TT. I could beat people with superior physiology simply by being trained for the TT position.
Now when I walk into my garage for a “TT bike day” I often cringe inwardly looking at the 23mm tires, and then grab my road bike instead.
I make up the difference by spending 100% of my Zwift time in the TT extensions.
It seems that Zipp is saying that a glass smooth wood floor is the cut-off between hooked and hookless with respect to optimal presure for the majority of riders. At this point, that is a very helpful exclusion - for them.
Almost an indoor / outdoor “determination†by Zipp.
However, outdoor testing shows a whole lot of conditions (road surfaces) where pressures over 5 bar is faster. As the article points out most TT and triathlons are held on normal road surfaces as opposed to chipseal or cobbles.
I think it is JP Ballard of SwissSide who likes to remind people that the Laws of Physics haven’t changed. So you can’t ignore the A in CdA. Now it would take a real aerodynamicist to tell you if widening the entire tire/wheel system can change the overall shape in a way that Cd is reduced and if that change can offset the 12% increase in A of going from a 25 to a 28.
As mentioned before, reliable test data finds real world situations where the fastest pressures exceed the 5 bar limit, so I think it is incumbent on companies like Zipp to demonstrate that their pressure calculations are correct and that Silca, SwissSide, Marc Graveline, Premier, AeroCoach,… are wrong (as an example, Marc found that Sylvan Adams was fastest on a 23mm front tire during their testing for Master’s Worlds).
I think the real solution to the hookless issue is to reduce the stretch in the tire bead. If hookless tires stayed on at 7 bar there would be no debate that it was the way to go. Maybe we will see wire beads come back in style.
However, outdoor testing shows a whole lot of conditions (road surfaces) where pressures over 5 bar is faster. As the article points out most TT and triathlons are held on normal road surfaces as opposed to chipseal or cobbles.
In a previous Post I had suggested (tongue in cheek) that they should use a titanium wire bead, and eliminate the pressure issue.
Quote Ronan McLaughlin @ Escape Collective - "The dimensional conversation highlights one inherent design challenge with hookless road systems. For all the talk of the missing hook, rarely mentioned is the dimensional and customer-expectation hurdles manufacturers must scale in producing hookless road system that is both safe and easy to use from a tyre installation standpoint.
One could argue a truly safe hookless road system should consist of a steel-bead, stiff-walled, non-folding tyre. That tyre should be mounted on a rim with a BSD, flange height, and rim well depth all exactly to standard.
The only issue with such a system is that it would prove all but impossible to install a tyre at home, let alone do any roadside repair that required more than a plug, some sealant, and air. The claimed and debated benefits of hookless road system may exist, but if they do, they do not come for free. The cost is either a thumb-busting process for changing tyres, or a system that allows for easier tyre mounting but is perhaps more prone to tyre dismounts." unquote
…and since moving away from tubular tires, when was the last time you had to change the whole tire while out on the road?
Are there issues with pressure for hookless and mid-race flats? Seems like they have a fairly narrow pressure window (high enough to ride, low enough to not have blowoff risk), and inflating with a CO2 isn’t exactly science.
Is the rim brake track still in tact on the new super 9 like it was on the older version even for the disc brake version? It’s had to discern from the pictures.
I think this version is a little more expensive than its predecessor. Maybe $100-200 more.
Is there any aero data that can show the delta between the older (25mm optimized) vs newer (28mm optimized)?
Edit: Is this the first hookless disc? I’m a little surprised zipp came out with one before enve.
I have a question.
What was there first when designing hookless wheels.
The design and they, the manufacturers, found that the limit a tire stayed on safely was 5 bar max.
Or was the limit 5 bar rule already there and the design based on this existing rule of 5 bar?
I mean, is it technically not possible to create a hookless wheel that can hold a tire on at, lets say, 6 bar?
Why was it set on 5 bar at some point? Was this the result of testing after the design was finished and they found it couldn’t hold a tire safely beyond that pressure.
And started calculating optimal pressure to weight with that as a starting point?
Jeroen
i think what you might find in the future is that max pressures for hookless will scale with tire size. the 5 bar max was pretty arbitrary. i think that’ll get tuned. however, what i think you’re likely to find is that 5 bar for tires 28c and larger is plenty enough for almost all people in almost all use cases.
Would you care to share some bike count data from the last Kona and/or Nice? Or at least the pro bikes, please. We would clearly see how few of those pro riders rode anything more than 25mm in the front.
i will share any data i have. i wasn’t in kona or nice last year; i think i might be able to help get tire size counted. just, it’s hard to count. you have to almost just ask those taking their bikes in what tires they’re riding. or, if it’s just the pros ask them prior to or after their races via some other contact method.
However, outdoor testing shows a whole lot of conditions (road surfaces) where pressures over 5 bar is faster. As the article points out most TT and triathlons are held on normal road surfaces as opposed to chipseal or cobbles.
i’m not convinced of this. if you’re talking about 28c and up. i don’t think we’ve yet had that much testing on a 28c tire for TT applications. for Crr, that 28c tire in, for example, silca’s calculator swells to 30mm when you put it on a hookless road wheel, because those wheels have such wide bead widths and silca specifies measured width. you have to get to a very smooth road before you exceed 5 bar on a 30mm measured wheel. and that’s silca, which is going to yield higher pressures than what the manufacturers say their pro teams are using. i think this is one of those areas where we must agree to disagree pending some moment where those testing generate more agreement in their results.