Zipp 303 S for Disc Brakes Carbon Clincher = Hookless What did I miss?

Triathlon Forum
1

Looking for new wheels for a road build and found these after some research:

https://www.probikekit.com/...l?variation=12509799

https://mybikeshop.com/...incher-wheelset.html

Why do they call these wheels “clinchers”? They are hookless and therefore for tubeless. What did I miss? I still like a wheel that has the option to run clinchers or tubeless so has the “hook” or ridge. I do not need help finding this option, just wanted to get input on why Zipp calls these clinchers instead of Zipp 303 S for Tubeless or something to that effect.

Sorry if this has been covered.

Thx!

2

Why do they call these wheels “clinchers”?
Because, while “clincher” is sometimes used to imply inner tubes, it is often also used to refer purely to the scheme of retaining a tire through the use of beads within a rim center channel. So what you’re calling “clincher” can be called “tubed clincher”, as opposed to “tubeless clincher.”

In the same way, for tires that use a glue-on retention in the rim’s center channel it is possible to refer to “tubed tubulars” versus “tubeless tubulars.” The latter is obviously uncommon, but is not completely nonexistent.

They are hookless and therefore for tubeless.
While modern hookless rims are typically only rated for use with tubeless tires, this isn’t because there’s any inherent problem to running inner tubes on a rim without hooks. It’s just done as a response to the current state of standards: hookless rims have less safety margin for blow-offs, and tubeless-rated tires are theoretically more-guaranteed to meet that safety margin. Most hookless rims still “allow” you to employ inner tubes if you so desire.

Go back half a century, and it was the norm for clincher-equipped road bikes to use hookless rims and inner tubes.

3

hookless rims have less safety margin for blow-offs, and tubeless-rated tires are theoretically more-guaranteed to meet that safety margin.

I’m not here to debate specs, but I’ll offer my experience.

I have had a couple of experiences with traditional clincher tires blowing off. One was because of a loose-fitting Specialized tire. Anything over 90 PSI and it blow off the Mavic rim, it just didn’t engage the hook in the rim well enough. I’ve also had clincher’s blow off because of pinched (latex & butyl) tube. One time was after a flat when I wasn’t careful enough to check for it (butyl), and the other time it was pinched after it was aired up after being totally flat (latex).

I’ve not had any negative experiences on my 303S wheels, I’ve had them since mid 2020. Multiple sets of tires. No flats. No blowoff.

Overall, I suspect the removal of tube related problems may make blowoffs less common for the average tubeless user, even if the actual spec is less forgiving, assuming sensible pressures are used.

4

Hi KTM 250,

The 303 S is designed to be ridden with tubes or tubeless, but the caveat is that tubeless tires must be used. Tubeless tires have a stiffer bead, and tighter tolerances on fit, this guarantees the tire will stay on the hookless wheel. Tubes are absolutely usable if and only if you use them with a tubeless tire.

I hope this clears up your confusion.

best

Nathan
Zipp product manager.

Looking for new wheels for a road build and found these after some research:

https://www.probikekit.com/...l?variation=12509799

https://mybikeshop.com/...incher-wheelset.html

Why do they call these wheels “clinchers”? They are hookless and therefore for tubeless. What did I miss? I still like a wheel that has the option to run clinchers or tubeless so has the “hook” or ridge. I do not need help finding this option, just wanted to get input on why Zipp calls these clinchers instead of Zipp 303 S for Tubeless or something to that effect.

Sorry if this has been covered.

Thx!

5

Hi KTM 250,

The 303 S is designed to be ridden with tubes or tubeless, but the caveat is that tubeless tires must be used. Tubeless tires have a stiffer bead, and tighter tolerances on fit, this guarantees the tire will stay on the hookless wheel. Tubes are absolutely usable if and only if you use them with a tubeless tire.

I hope this clears up your confusion.

best

Nathan
Zipp product manager.

Looking for new wheels for a road build and found these after some research:

https://www.probikekit.com/...l?variation=12509799

https://mybikeshop.com/...incher-wheelset.html

Why do they call these wheels “clinchers”? They are hookless and therefore for tubeless. What did I miss? I still like a wheel that has the option to run clinchers or tubeless so has the “hook” or ridge. I do not need help finding this option, just wanted to get input on why Zipp calls these clinchers instead of Zipp 303 S for Tubeless or something to that effect.

Sorry if this has been covered.

Thx!

Thanks everyone. I understand it better now, but it is still a bit messy when coming at it from both sides of the equation (wheels & tires) and naming convention used by the makers.

Nathan,

As a PM I am sure you know your stuff, but this is what Zipp has on spec for this wheelset with regards to running tubes:

Note: The new Zipp 303 S are designed to be run as Tubeless. Zipp recommends to run tubes in emergency situation only.

Does not give me a warm fuzzy about it doing it. Is this statement from lack of testing or being conservative…?

6

Sorry to go in another direction but has anyone used the new 404 firecrests as a gravel wheel? I see the marketing for the 303s for gravel but are the internal/external diameters different? I would like to use a wheel set for road but also for gravel races.

7

Hi KTM 250,

The 303 S is designed to be ridden with tubes or tubeless, but the caveat is that tubeless tires must be used. Tubeless tires have a stiffer bead, and tighter tolerances on fit, this guarantees the tire will stay on the hookless wheel. Tubes are absolutely usable if and only if you use them with a tubeless tire.

I hope this clears up your confusion.

best

Nathan
Zipp product manager.

Looking for new wheels for a road build and found these after some research:

https://www.probikekit.com/...l?variation=12509799

https://mybikeshop.com/...incher-wheelset.html

Why do they call these wheels “clinchers”? They are hookless and therefore for tubeless. What did I miss? I still like a wheel that has the option to run clinchers or tubeless so has the “hook” or ridge. I do not need help finding this option, just wanted to get input on why Zipp calls these clinchers instead of Zipp 303 S for Tubeless or something to that effect.

Sorry if this has been covered.

Thx!

Thanks everyone. I understand it better now, but it is still a bit messy when coming at it from both sides of the equation (wheels & tires) and naming convention used by the makers.

Nathan,

As a PM I am sure you know your stuff, but this is what Zipp has on spec for this wheelset with regards to running tubes:

Note: The new Zipp 303 S are designed to be run as Tubeless. Zipp recommends to run tubes in emergency situation only.

Does not give me a warm fuzzy about it doing it. Is this statement from lack of testing or being conservative…?

you can have your fuzzy if you want it. this is a tubeless system, and it isn’t simply a case of running tubeless tires, it’s running tubeless tires that meet the ETRTO spec for hookless. and… in running the tires at a minimum given width. that rim has an inner bead width of 23mm, so, your tire needs to be 25mm or larger. (frankly, i think it’s kind of silly to run anything less than a 28mm tire on that wheel.)

this is my writeup of the new 303 series, from about 2yr ago when they first came out.
here’s subsequent wheels zipp made using this hookless motif.
i wrote about pressures for these new wheels here.
here’s the intro article to tire compatibility for these wheels.
here is the global hookless tire/wheel compatibility chart we publish.
here is zipp’s compatibility chart for its wheels, which should match what we publish, tho i omit wheels that i don’t think you guys are likely to ride.

for road i now ride exclusively hookless, and the two wheelsets i’m riding now are made by zipp and cadex. i don’t have a problem finding tires i like, and i have a sneaking suspicion something major may get intro’d in the next couple of months.

knock on wood, in the 2 years i’ve been riding hookless, several thousand miles, i’ve had to have a flat.

8

Upon reading Slowman’s reviews, I went in whole hog with a Caledonia 105 and then the 303s. Decided to go with Pirelli Cinturatos (28). No flats in a year of riding. I do gravel, crits, and group rides with this thing. Riding @ 65 psi is what you’d expect, plush & no drama, I’m the guy in the group ride who takes one for the team in the echelon on the gravel, broken glass, racoons, on the side of the road. Sure the Zipps are pricy, but are a solid all rounder that I never have to think about. Just wondering if I should go to 32s for my next set of tyres? Anyone?

9

Slowman,

Running a 28 on that wheel is going to put the measured width around or 32. The external is 27. Having the tire 15-20% wider significantly impacts aero gains.

I’m sure it’s comfy but I struggle why someone would spend a 2k on aero wheels and then ruin it with tire width.

I understand the guidance put out but in a year or two we will look back and laugh at these set ups. The wheels have to get wider for such tires or put hooks in and run narrower like HED does.

10

So whatchya saying Willis? 28s or 32s for my crirs?

11

There is no right answer within etrto standard. The wheel external should have been make wider or hooks should have been used so you can size down.

For example. Hed uses a 21 internal and 30 external. Put a 25 on that wheel and it’ll measure 28 but the rim extends out to 30. That is much much better.

Zipps hookless measuring 23/27 does not allow you to pair any tire with decent aerodynamics.

12

Slowman,

Running a 28 on that wheel is going to put the measured width around or 32. The external is 27. Having the tire 15-20% wider significantly impacts aero gains.

I’m sure it’s comfy but I struggle why someone would spend a 2k on aero wheels and then ruin it with tire width.

I understand the guidance put out but in a year or two we will look back and laugh at these set ups. The wheels have to get wider for such tires or put hooks in and run narrower like HED does.

i don’t think your math rings true. i don’t have that particular combo in my workshop, but i have a couple for comparison. i’m running 28mm tires on a set of zipp 353 NSW wheels in the pic below.

that tire, inflated, on the that wheel, is 1mm narrower in width than the wheel.

i’ve got another combo, which is a CADEX hookless wheel with a 22.4mm inner bead width, and i’ve got a 32mm road tire on there, which is pretty mambo. that tire measures exactly 15% more in width than the rim.

in the first case i have a 3mm differential between tire and inner bead width (28mm tire on a 25mm inner bead rim) and that gives me a tire narrower than the wheel. in the other case, i have an almost-10mm differential between tire and bead width, and that gives me a tire that’s 4.3mm wider than the rim.

so, if we look at a 28mm tire on a rim with a 23mm inner bead width, i suspect (based on the two set ups that i do have) a rim transitioning to a tire that has about the same width as that rim (or if the tire is wider than the rim the difference would be scant). further, what you see with hookless is a smoother transition from rim to tire, kind of like this:

perhaps i have a blind spot, but i don’t foresee a future when i would look back and laugh at these set ups.

353nsw.jpg
195306-largest_CADEX_WHEELTIRE.jpg

13

so, if we look at a 28mm tire on a rim with a 23mm inner bead width, i suspect (based on the two set ups that i do have) a rim transitioning to a tire that has about the same width as that rim

My worn out Schwalbe Pro One tires, in 25mm, on my 303S wheels, measure about .5mm wider than my rim.

14

so, if we look at a 28mm tire on a rim with a 23mm inner bead width, i suspect (based on the two set ups that i do have) a rim transitioning to a tire that has about the same width as that rim

My worn out Schwalbe Pro One tires, in 25mm, on my 303S wheels, measure about .5mm wider than my rim.

that sounds like a pretty nice set up. i would guess you run them at about 65 or 70 psi?

15

that sounds like a pretty nice set up. i would guess you run them at about 65 or 70 psi?

Thanks. Yes, 65-70 and I’m around 175 lbs.

A few of my ride buddies complain about the roads (rough chip) but my setup is very smooth. I think my wheel setup is a lot of the difference.

16

So a 25 pro1 runs 27.5 on your set up and back to the original 28 I’d say it’s going to run 30.

For the rule of 105 the right tire for that rim (aero wise) is 25.5. So both set ups are pretty far from ideal.

Nice set ups for sure. But if your spending 1500 bucks for tires and wheels these compromises shouldn’t happen. You can call this nit picky but the drag of getting this wrong is real.

17

rule of 105 questions:
is the rule 105% or more (if so, why wouldn’t manufacturers take that into account - too expensive/weight/manufacturing cost)?
if aero is optimized right around 105 and gets a little worse at less AND at more then one would assume almost 105 is still really close to best

does hookless and the ‘better’ tire rim interface change the calculation of 105 (i.e. with hookless is 100 just as good as 105 with latex tubes?)?

if 28 tire has so many performance advantages in grip comfort on anything less than perfect road (such that pro cyclists seem to only be using 28)
AND darn near the aero of the105 rule
does this mean that going all in on aero only makes sense for a TT (triathlon) - where the good ‘old’ 25 may still rule the day?

i’m likely to pick next wheels for optimal 28 tire performance (looks like 23 internal zipps OR enve 4.5ar to me) cuz i’m also old and performance/safety on descents figure pretty high on my wish list these days. thanks for letting me be a fly on the wall for these debates - sincerely, rick

18

Or some manufactures got it wrong. If you want to go that wide get a wheel that matches. But a 23/27 hookless design will never allow proper aero interface. There need to be a bigger difference between the two measurements. You can have 28s and the rule 105. Some manufactures already do this and that’s what everything will go to in the future, if people attention.

19

So a 25 pro1 runs 27.5 on your set up and back to the original 28 I’d say it’s going to run 30.

For the rule of 105 the right tire for that rim (aero wise) is 25.5. So both set ups are pretty far from ideal.

Nice set ups for sure. But if your spending 1500 bucks for tires and wheels these compromises shouldn’t happen. You can call this nit picky but the drag of getting this wrong is real.

well… not necessarily so. i’m measuring the rim at the distal edge. if it’s a toroidal wheel, the rim is still fatter than the tire.

beyond that, all of the data used to compile the hypothetical construct that is the rule of 105 were done on older wheels, thinner rims, and hooked beads. i’d like to see fresh data on current wheels before i stipulate to that as a hard fact on current road wheels. you’re right, drag is real. as is rolling resistance, mechanical vibration, muscle vibration, flat resistance, safety.

20

that sounds like a pretty nice set up. i would guess you run them at about 65 or 70 psi?

Thanks. Yes, 65-70 and I’m around 175 lbs.

A few of my ride buddies complain about the roads (rough chip) but my setup is very smooth. I think my wheel setup is a lot of the difference.

you’re right.