WhyFi

Because you're stuck in an old school way of thinking?

100psi over real-world roads is silly; feeling every little bump and crack isn't fast, it's wasted energy.

sumgy

I have read reports that suggest that too much pressure is actually as bad as too little for rolling resistance due to micro vibration at higher pressures.

For what it is worth, I run 80psi and am 85kg.

MoAlpha

There is a similar recommendation from Hed for their 21mm internal dia. rims. I am using about 65 psi in 25 mm tires and it works in terms of comfort—always a relative term—and handling.

This is with tubes.

sumgy

Oh, I am out then.
No idea, as even after many years of road tubeless being around, I still see it as a pointless gimmick.
The 80psi I mentioned is for tubed wheels and tyres.

burnthesheep

Oh yeah, there’s also the exploding Enve TL wheels if you don’t use the perfect rim tape and valve combo. Gotta love that for $2500 a pop.

It leaks into the “fairing” of the aero wheels and explodes them.

Sy Reene

Maybe I am, but it just seems a huge difference to go from (2-3yrs ago) advice to run 25mms at about 90-100psi to now 60psi Tubeless. I'm really just asking if there's a modern update to the (still available) tire inflation calculators that used the "15% drop" theory, but built or optimized for tubeless? From one article I came across, the chart below suggests that somewhere around 6 Bar seems to be optimum for speed on roads, which would presumably be the goal of someone investing this many $$ in a wheelset? 6 Bar = approx. 87psi. The chart was referenced in this article.. which mentions a "MyMavic" app.. Has anyone downloaded and played with this by chance? https://www.cyclingweekly.com/news/p...-answer-383174

WhyFi

Does the chart suggest that? I don't think that it does. I think that the chart reports what they saw in their study, but doesn't make any blanket suggestion. Note that there no references to rider weight, tire size and "rough" is rather vague, too. Even at the end of the article that you cite, they close with, "We reckon that the Mavic pressure recommendations are a bit higher than we’d normally ride. But then we do have especially bumpy road surfaces here in the UK."

The long and short is that there is no quick and dirty "15% drop is optimal." Track down that Cycling Tips podcast about tire pressures and give it a listen.

Ald1 

You mean like this?
After seating the bead with a Hot Shot, I used a hand pump and this happened at about 75 lbs pressure. In defense of ENVE they covered this under warranty and turned it around in less than a week. They DO now supply a "leaky" nut to secure the also supplied valve stem. This is designed to let air out of the chamber to prevent the above if your rim tape fails. They also supply rim tape which, BTW is the best I've ever used. There was also a caveate not to exceed 80 lbs or the rim could explode if the tape failed. Mine explode under 80lbs. Of course I did not use their nut, stem or tape. This particular wheel was a replacement under their crash protection at 1/2 price (Before they changed their policy to free AHHHHHH!). The original wheel did not come with a leaky nut so they are aware of the issue and have corrected it but as I pointed out to them they do not require you to use the supplied tape etc. Anyway combined with the Pro Ones the system seals perfectly without any sealant as I belive any rim tubless combo should. A great ride! I have longer stories with ENVE and it's a love hate relationship. Maybe another day and another post.

FlashBazbo

Except for UST wheels without rim tape, any tubeless wheel will blow its goop if the tape job doesn't hold up. I had it happen on a set of HEDs recently. Frustrating.

CarloM

Yikes! Well I ordered the official ENVE SES 5.6 tubeless kit (rim tape, valves, tool, etc.) and had my LBS who sells ENVE wheels do the install, so knock on wood I think they would have done a good job of it (they've done a great job on everything else I've needed them to do). Keeping my fingers crossed!

FlashBazbo

I've got a similar setup to the OP. I run 25mm Conti 5000TL tires tubeless on ENVE 3.4 Disc wheels. I weigh about 175 and I usually inflate the tires to 72psi front / 80 psi rear. If I'm expecting to ride a lot of chipseal on a given day, I'll reduce both tires to 70psi. 70 to 80 psi seems, to me, to be the breakover point between comfort (lower pressures) and improved rolling resistance (higher pressures). Below 70psi seems too squishy and sluggish to me. Above 80psi seems really harsh riding.

I'm accustomed to running tubeless at lower pressures. I run much lower pressures on my wider gravel bike tires. But road tubeless seems to get really sluggish, really suddenly, when you pass a certain pressure threshold.

Seattle Forrest

They asplode because they're crabon!

Seattle Forrest

I run about 60 psi in my 4.5 ARs with 28 mm tires. Or tyres if you're British. I put about 5 psi more in the rear.

Cypress

Anecdotal in a way, but I run the tubed GP5K on HED Ardennes Black wheels (21mm internal) and weigh 164 pounds. HED recommends 67 PSI for me. I run mine at 73F/75R and could probably stand to go lower. It isn't slowing me down in the least bit. It's common to run tubeless lower than tubed, and you're lighter than I am, so a lower pressure seems appropriate. Follow the rim manufacturers recommendation, as they will have a better idea of "optimal" for their designs than the tire manufacturer.

ThermionicScott 

~15% drop is the modern thinking, it's just that it takes roadies 20+ years to accept new ideas. (Frank Berto's original article came out in the late 1980s.) The only difference for tubeless is that you can run a bit less pressure if you want.

If anything, what the latest research is showing is that with good tires, there is a big sweet spot in the middle for optimal comfort and rolling resistance. Methinks you should be less dependent on charts and graphs, and just ride yer damn bike.

Spoonrobot 

It takes a very stiff tire (or an extremely lightweight rider) for 60psi to be 15% drop. 700cx25, speaking. For my combined bike+rider weight of 197 pounds using tubed 700cx25 measuring actual 26.6mm, GP4KS2 60psi would be ~45% drop.

redlude97

You think thats bad? I pinch flatted a new tubeless tubular, its a goner and I can't even patch the inside

Drew Eckhardt 

How much do you weigh?

I like 70 psi front and 80 psi rear with 135-150 pound rider weight on 25mm GP4000s with conventional tubes.

60/70 doesn't risk pinch flats, but feels squishy, slow, and vague.

YMMV.

CarloM

145lbs. It seems I've settled on 70psi as a minimum, and may try 70/75 F/R on my next ride. I don't feel that it's squishy, slow or vague, but I do notice at 70/70 it absorbs the road bumps much better than when I tested at 80/80, and didn't feel appreciably slower (set a few PRs on Strava segments on 70/70)

sumgy

This is what I don't get about the whole tubeless hype.
I run those sorts of pressures in my Vittoria Corsa tyres with tubes.
I weigh 85kg.
I rarely get flats and never get pinch flats.
What additional benefits are you getting?
Then again daily riding around on carbon rims choosing over $1000 makes no sense to me either.

WhyFi

So don't run tubeless. If I didn't get flats very frequently, I wouldn't. But I do. So I do.

sumgy

So how does tubeless help if you tear a sidewall or run over glass or a nail?

sumgy

But that didn't answer my question either.

WhyFi

Depends on the size of the resulting cut. In 3+ years of running tubeless, I've had three cuts that didn't permanently seal; two of those cuts totalled the tires. Tubeless obviously isn't going to help in these cases, but they're few and far between for me. What's a regular occurrence, though, are run of the mill punctures that would leave me changing a tube of the side of the road. Those have been essentially eliminated.

I don't understand why it didn't. For me, eliminating routine punctures is a huge benefit. If my experience were like yours, and flats were a rarity, there would be very little benefit and no motivation to go tubeless. So I wouldn't.

canklecat

Optimal tire pressure will always involve some guesswork.

Last week's urban group ride bashed across some unexpectedly rough railroad tracks. Two riders got pinch flats. One weighed no more than 110 lbs, probably less, on a lightweight carbon fiber bike with 700x23 tires, and said her tires were fully inflated. I checked the undamaged tire and it definitely wasn't low, especially for her size and weight. Classic snakebite tube pinch marks on the flat.

I weigh 150, was riding a 25 lb steel road bike, and had my 700x25 Conti Ultra Sport II (cheap but good) set to 75 psi front, 90 rear. No problems bashing across the same tracks. I can't bunny hop but may have unweighted the bike a bit at a crucial moment, I dunno.

In the past four years, typically running tires on the low side for comfort, I've had one pinch flat. And that was pretty extreme. I was squeezed between a parked truck and another oncoming truck that veered into my lane. I was focused on not getting squished and bashed across a brick I didn't notice. Classic snakebite, my first ever. I doubt any tire pressure would have helped in that case. I was just happy the tire and rim weren't damaged.