i, like you, have gone 2 years without a flat with tubes. but then the flats all come one atop the other, bam bam. at least, that's my experience. feast or famine.

here's my biggest remaining hurdle with all these new wheels and tires. every now and then you find a combo that just won't bead up. hooked or hookless. that's the problem with wider rims. but it's mostly limited to 25mm tires. if you're trying to put a 25mm tire on a 23mm or 23mm inner bead width rim - hooked or hookless - you may find it hard to get enough of the tire over the rim well. this is why i pointed out that sometimes a good option is a tire that's made by the wheel company. of course, it's got to be a good tire. but the wheel makers aren't going to produce a tire that can't easily, reliably mount on a wheel. in general if it's a 28mm tire or larger you're home free.

but as to this "difficulty about mounting tires," the difficulty is limited to this. i never really got behind road tubeless until the 2019 ETRTO manual was published, and the first tires came out that conformed to that spec. then the wheels started coming out. we're about to see the 2022 manual drop. over these 3 or 4 years a new generation of wheel and tire mean you don't have these fitment issues. almost every tire mounts hands-only, hooked or hookless. have the ETRTO step in to referee made all the difference.

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Dan Empfield
aka Slowman

very interesting on the data with clx 64 external width 30+ and different tire widths (on a 21? or 20mm? internal bead).
does this suggest the rule of 105% really should be 108% or 110% or another number?

my feeble brain says if 105 rule is consistent across wider internal/external widths then a great handling/feeling 28mm tires just needs a wider external rim. maybe the data referenced above says my feeble brain doesnt get it?

will gravel wheels go hookless eventually also? the tire/rim interface (and definitely the rule of 105) seem inconsequential compared to any vibration dampening efficiency that may be occurring (and the lower pressure/better handling which may also = even more vibration dampening).

it seems like there may be a race between supply chain issues/availability (when can we get some of this new tech) and
when will we have more definitive answers about the science.....

one piece of tech i'm definitely springing for is shimano 12 speed (ultegra) for big euro mountain climbs (11-34 sounds great!) and my old man declining ability.

It means that's the 105 "rule" isn't a rule. The 105 "rule" means follow it and you won't see a huge jump in drag. People took that to mean if you follow it and you can have no very little impact to drag which is not the case. Even if you go with a wider rim with a 28mm tire, you'll get more drag just due to more frontal area. See the latest zipp 404 refresh. They admitted by going super wide they made the 404/454 1/4 watts less aero. But they are assuming you're riding on dirt so the rolling resistance makes up for it. However they don't state that their numbers only apply for riding on dirt. This is what I mean by dishonest marketing.

I'm also not sure if wider tires will have more vibration damping assuming similar casing tensions and riding on good roads.

Anything not on the road is a good use case for hookless, and has been using hookless for a while.

I haven't read through all 20 pages...yet. Are the new tires and wheels compatible and "easy' to change? Some of the older ones were a bear.

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Mike

the problem in the past was a lack of an accepted standard. because of this sometimes the tire makers would make their products slightly small; the wheel makers slightly large; and if you got the wrong combo of tubes and tire boy were you in trouble.

i didn't start to get really animated and vocal about tubeless, in road and tri, until 2019, because that's when the ETRTO - the euro authority for all pneumatic tires of every type - published the first set of standards for tubeless, and that was both for "crotchet" style rims and hookless beaded rims. this meant that wheel makers could make products exactly to spec and didn't have to cheat large. tire makers, the same, and they didn't have to cheat small. all everyone had to do was build to the stated spec. building to the ETRTO spec was everyone's liability get out of jail free card. finally, with tires and wheels made to that spec the products were easy to get on and off. the first tires made to that spec were the schwalbe pro ones launched in 2019. since then conti made a tire and we're awaiting what vittoria will do. both schwalbe and conti now have tires that will go on rims with hookless beads.

it wasn't just major dimensions that were called out in the ETRTO's manual, for hookless beads it was contours and transitions in the rim. this meant that tire makers could really dial in the way their beads were made, and instantly the wheel/tire fitment got so good you could pump up a tubeless tire in a hookless beaded rim and that tire would keep that pressure for days or weeks, even without any sealant added.

when you read about bad histories with road tubeless, it's important to look at the vintages of the products. you're going to have a lot more crime in a society where you have no laws (or enforcement). that was road tubeless pre-2019.

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Dan Empfield
aka Slowman

The short answer is "mostly yes." It's probably still possible to find new wheel/new tire combos that don't work well together, but overall the industry is in a much better place than just 2-3 years ago.

About 2 years ago I had my first instance of putting a TL tire on with just my fingers and doing the initial inflation with just a regular floor pump. That's huge progress from 5 years ago.

This was one thing that bothered me about the original article. It's undeniable that on a given wheel width, a narrower tire is going to be more aerodynamic. This has been known since the days of BikeTechReview's Hed3/Zipp404 testing. The above chart is probably similar to the ~2004 aero testing. If my calculations are correct, that aero drag difference is about 1.4W @ 22.5mph between the 22mm and 28mm tires. (I picked that speed because it's close to my 1/2IM average these days.) That's not a dramatic difference, but it's noticeable.

The BRR data clearly shows 100-120psi as being *significantly* lower rolling resistance than 60-80psi. This is from his special Rim Width Test from last January. I haven't seen any data that suggests that, on typical pavement, 60psi is faster than 110psi. Maybe on cobbles or gravel it is, but on a road it is not. The difference is even more substantial, around 11.5W vs 8.75W. That's a 2.75W edge towards the higher pressure tires at 18mph or around 3.5W @ 22.5mph. Tom Anhalt's bumpy roller data from ~2007 showed higher pressures to be faster, and not by a small margin. It was dramatically higher at 80psi than at 120psi, on the order of 10W or more.

CRR of wider tires is lower, though. For example, BRR's data on the GP4000s a few years back had the 18mph/110psi drag at: 23mm = 12.8W; 25mm = 12.6W; 28mm = 11.8W. Scaled up to 22.5mph that is 16W, 15.75W, and 14.75W. That gives a 1.25W edge towards the 28mm tire, pretty much the same as the 1.4W aero advantage in the opposite direction. So probably aero vs crr is a wash.

Don't get me wrong, I like the idea of wider tires and tubeless and lower psi for comfort and flat resistance. I have a Mavic Comete Pro UST front that I'm experimenting with. My initial experience with tubeless was horrendous, literally fighting for over an hour to get the Vittoria Corsa Speed onto my rear FLO disc. I gave up at that point and went back to inner tubes. The newly purchased Comete was a bear with the Mavic Yksion Pro UST (gen1). It took two people and 3 levers to pop the bead back into the center recess. I am planning to try out the Comete front with either the Gen2 Yksion or other tires.

The summary of my gut feel is that narrow 100-120psi tires are going to be faster on a wide rim than 60-70psi tubeless. I'd love to see some science that says otherwise.

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You are correct in that wider narrower tires at higher psi are going to be faster than wider tires at lower psi assuming the pressures are scaled correctly and your road surface is good.

The thing all the tire width rolling resistance on rollers/drums miss out on is that when you increase tire size you also need to drop pressure to maintain the same casing tension to have a true comparison of rolling resistance of various tire sizes. Once you do so, the rolling resistance advantage of wider tires (on good roads goes away).
I would caution against inflating tires as high as they can go, as most of the roller testing is on perfectly smooth surfaces, which roads are not. Silica has some data on tire pressures in the real world, but I think many of his road surfaces are rough than I would like

Also unless your wide tires are super wide, the delta between pressures shouldn’t be 40 psi.

there's a number of factors that need to be introduced into the conversation, that bear on the data to which you refer.

1. according to some very smart people, some of whom we're be interviewing here in the coming weeks, the BRR test apparatus and protocols have limits. i think as we shine a light on this process we'll see where the data is reliable and where it isn't.

2. there is for lack of a better term legacy data. the testing on rim brake bikes, and on tubed wheels, and on bikes not optimized for larger wheels, is legacy data. if you go back 4 or 5 years to our discussions on this forum one of my arguments in favor of disc brake tri bikes is that you could build the frame in a way that anticipated no rim brake; you could build a wheel in a way that did not require a braking surface; and you could build an entire system with that in mind.

3. we haven't yet found a good vocabulary for organic energy losses that flow from unoptimized equipment. not just the impact of vibration on equipment, but on the body's ability to produce power.

4. let's say these new wheels/tires are no more aero, and they don't roll faster. let's say they just match the old wheels/tires in data-based performance. in that case i'm all in, because these systems are more comfortable and less likely to flat.

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Dan Empfield
aka Slowman

I'm not quite sure I understand you regarding pressure vs tire width, there's two parts to the arguments I've seen:

1) There's the argument that a wider rim makes for lower CRR. At a fixed tire width of 25mm the BRR data showed a very small improvement in CRR when going to a wider rim. The roller data averaged 9.93W / 9.88W / 9.45W going from 18 / 22 / 26C. That's with constant tire width of 25mm. I'd argue that the difference is insignificant, with a 5% difference in wattage vs a 45% difference in width. That's probably where the 105% argument comes in, so picking the optimum width aerodynamically is the best choice.

2) The other argument is that wider tires have lower Crr at their optimum pressure. BRR's roller data shows 23, 25 and 28mm tires with the same curves, just with a lower CRR for 28 vs 25 vs 23 at all pressures. You could look at it two ways: a wider tire always has lower CRR at any given pressure. This is true. It's also true that a 23mm tire at 120psi has the same CRR as a 28mm at about 80psi. Clearly the 28mm will be more comfortable at 80psi, and be equivalent from a rolling resistance perspective...but a watt or two worse from an aero perspective. You could also say that a 28mm tire at 120psi will be about 2.5W faster than at 60psi. On rollers that's true. That's where the Silca calculator comes in. Here's the BRR test for reference: https://www.bicyclerollingresistance.com/...-gp4000s-ii-23-25-28

But I think there is a disconnect on using the Silca calculator. It does not say which setup is the fastest for an application, it only attempts to find the "optimum pressure" for a given combo. For example, the Silca tire pressure calculator comes up with 114.5psi for 23mm tires on new pavement, 100.5psi for 25mm, 84psi for 28mm tires, and 68psi for 32mm. But that does not tell you which of the four combos is faster overall. There may be a big overall wattage difference between them. And it says nothing about the aero penalties of a 32mm tire vs a 20mm tire.

I'll have to look up the old "bumpy roller" data again. My recollection was that for a single 23mm tire on bumpy rollers, it was about 6W slower at 80psi than at 110psi.

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I'm all for some additional data and roller vs pavement comparisons. Every roller comparison I've seen shows decreasing CRR as psi goes up, but clearly there's an optimum in there somewhere. Heck, I used to ride 18mm Michelin HiLite SuperComp HD tires...I think I still have one in my closet of old random stuff.

Regarding #3 that's going to be hard to quantify. I've ridden the chipseal roads out at the Great Floridian course in Clermont a lot, and concluded that if I was moving fast (well above 20mph) a high psi tire was fine. I'd tend to "glide" over the tops of the chips at high speeds. But at lower speeds (under 20mph) it was bone-shakingly horrendous and tough to put down the power. That subject is horrendously complex.

To your point #4 I totally agree. If they are data-wise equivalent (or slightly better or a tiny bit worse) then I'm all for it. Based on what I've seen so far a 25-28mm tubeless setup on optimal width rims is aerodynamically a bit worse than a 20-23mm on a narrow rim, but better Crr. If those end up being a wash at my typical race speeds (or daily ride speeds) then I'll switch to tubeless as long as I can mount and unmount them. The sealant issue probably isn't too bad for me at the moment, I've been riding 5000-6000 miles/year. So I'll wear a tire out around the same time the sealant gets gunky. New tire...new sealant...ready to go!

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Regarding Crr vs pressure, I looked back at the Silca part 4B again. The super-rough graded data is interesting but not relevant to any real roads. Their "Coarse Intermediate" is similar to chipseal, and then the final paved surface looks pretty normal. The "optimum" tire pressure was around 90-100psi on chipseal and 110psi on fresh pavement. 2 years later that optimum pressure is still 110psi, but the Crr improvement at 110psi is pretty substantial compared to 60psi.

Looking at their "new pavement vs 2yr old pavement" shows a line that's pretty much expected. 90psi is about 42W with their 25mm GP4000sII tires. 110psi is only about 40W (my estimate from the below graph). 60psi is dramatically worse at 50W. For chipseal the optimum was 100psi with only a 1W penalty to 90si and 5W penalty to 60psi.

The unanswered question is...what's the same data at 23mm or 28mm or 32mm? Does it follow the same curves? Or are the breakpoints actually different? Theory says yes, but reality is not always so consistent...

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...into the wormhole I go...

This is such a fascinating subject from a technical perspective. However I'm struggling with a far more prosaic question for my tubeless setup:

Schwalbe Pro One measured width of 25.5mm on a 27mm external width rim (FYI tire nominal is 23mm) vs
Conti GP5000 measured 26.5mm on the same rim (tire nominal is 25mm).

The GP5000 has a better CRR (note: Schwalbe isn't the latest TLE/Addix but 2018-19 model), but
Schwalbe fits the 105% rule better

Use case: 70.3 at 22mph (36 kph); good road surface; yaw angle <10 degrees

Any can anyone explain why Conti has dropped the 23mm tubeless from its line-up?! It seems this tire is going to be too wide on many if not most sets already in use i.e. if you're going to make a fast CRR tire also aero optimise it, please !!!

Continental didn't drop a 23mm tire from its tubeless lineup.

Continental never produced a 23mm tubeless tire.

I wondered if it's possible to garner a consensus on the best 28mm tubeless tire for all round use on a road bike that's hookless compatible (the odd race, lots of training, mix of shitty and good roads)? Appreciate no tire will nail every criteria but wondered if there were any seen as the best all round options. I'm being suggested the Schwable One, is that a good shout?

I’ve put a lot of miles on 28’s from Conti, Schwable and Michelin. The Conti experience is all TL on hooked rims, but the other two have been on hookless Enve AR’s and Zipp 303FC. I’d be running the new Conti 5k TR except I have a supply of Pro Ones and Michelins to finish off first. I don’t find that any of them stand out that much better than another in use except the TL might be less flat prone. So if in doubt I’d say roll the fastest rubber.

interesting you ask that. if you go into bicyclerollingresistance and you set the filters in particular ways you get differing results. for example, if you want a 28mm or larger tire and you stipulate 60psi rolling resistance, and a flat resistance score of 50, it's a zipp tangente that wins. but i don't stipulate that brr is the for-certain best equipment/protocol for rolling resistance.

i've run a lot of schwalbe pro one in 28mm and 30mm and having nothing but good to report. currently i'm running a 32mm CADEX tire on a CADEX wheelset on my cervelo R5 and i just find that a brilliant combo. that tire comes in a 30mm as well. at 32mm i run it at 55psi and that's either correct or, if it's not, it's overhard by a few pounds.

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Dan Empfield
aka Slowman

I suggest you check the last paragraph of that post, somehow i think you left out a word. One sentence seems weird and very agressive to me, i feel like you missed an important "but". If i am wrong and you really do stand by that opinion on Schwalbe please feel free to remove this.

/Henrik

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Disclaimer: I have made a living in bike shops for more than 2 decades, so according to most people on this forum am not at all trust worthy

sorry. yes. you're right! thank you. my experience with schwalbe has been stellar, with this kind of tire. the tires i'm riding a lot lately on my road bikes are schwable and CADEX.

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Dan Empfield
aka Slowman

Just replying to the thread.

I think we all know that if you can get enough airlfow most every tire will seat so I recently went to Harbor Freight and picked up a blow gun for my air compressor (https://www.harborfreight.com/...-blow-gun-63568.html ) and slid a section of floor pump hose over the end and secured it with a hose clamp. The hose I used is slightly smaller diameter than a presta valve so when you push it on it will stay on without further retention required. I removed the valve core too hoping to remove one more airflow restriction (this may work with the core in but have not tried it yet). There is so much airflow it works ON THE FIRST TRY! I highly recommend this setup for anyone who has problem tires, the blow gun is only $5 but you may have to search around for appropriate size hose and of course you need an air compressor.

Rich

I have been trying to find gp5000 tubeless tires in 700x28c for months. Does anyone know where I can find these?

https://www.ebay.com/...id=711-127632-2357-0

I think you might have a small typo in the chart.
It is supposed to be 303 firecrest and you have 353 firecrest.

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Tiago
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Sponsors: : Blueseventy :

Some you win some you lose.

I had some Vittoria Terreno setup tubeless on a set of clincher Giant alloy road wheels but the new Gravelkings are so freaking loose in the bed of the rim that not sure I could put a whole roll of tape in there to get it tighter to pop onto the rim. Sadly perhaps will have to go tubes.

My tubeless rimset for the cross bike has the cross dedicated tires on it.

This super thread is too super for a neophyte. I’m converting the HED RC Pro Vanquish 6 and disc to tubeless. I have the tape, valves, and 25mm Conti TL. Should I have the 28mm? Should I anticipate any issue with the 25mm? Traveling with these wheels, any issues I should anticipate when compared to my regular tube experience? Once everything is installed, maintenance, any regular floor pump will do? Excuse the ignorance.