gregf83 

I'm 75kg and have had half a dozen or so pinch flats in the last 13 yrs. A 1" sharp rock will easily cause a pinch or a shallow chunk of missing pavement.

cxwrench

I've come up with pressures I like...my bike rolls very well, it's comfortable, and has plenty of cornering traction. I refuse to raise them to avoid a once or twice a year pinch flat. Anyone that claims that a 23 or 25mm tire at 115 is faster or has the same traction as the same tire are 90 or 100 is wrong. It's a fact backed up by physics. I am fine if that's just what you prefer but don't try to tell me that it's faster. The difference in traction should be obvious as well as the difference in comfort. How about CX racers? 33mm tires, most of the guys are always under 25psi at the rear. If it was that slow they wouldn't do it, would they. They benefit from an increase in traction as well. It's exactly the same with skateboard wheels...a 100 durometer park/street wheel won't roll anywhere near as well as a 70-80 cruiser wheel.

gregf83 

What do CX racers or MTB racers have to do with riding on smooth roads. Why don't you consider track racers. Do they race at 100psi?

Sy Reene

Silca's been referenced. Let's put this up there then:

Hiro11

Maybe I've been lucky, but I've personally never had all of the hassle others seem to have with tubeless. I have five bikes currently set up tubeless, including a fat bike, a gravel bike, a cross bike, a hardtail and a road bike. I ride a lot on all kinds of terrain and surfaces. I completed all of these tubeless setups myself. The first couple were rough but I soon learned what works and what doesn't, like any other skill. Maybe gear plays a role, I don't screw around with cobbled-together setups or processes. I have a $90 6 gallon Porter Cable compressor I got on sale from Amazon with a $60 Prestaflator gun, which together cost less than many of those absurd "pressurized chamber" bike pumps I see and works 10x better. I only use good quality tubeless ready tires, good quality tubeless ready rims and ridiculously overpriced genuine tubeless tape sized exactly for the rim I'm using. Maybe technique plays a factor as I follow a rigorous set of steps every time that I know will work. With all of that, I can confidently set up a bike with pre-taped rims (like most rims these days) tubeless in maybe 15 minutes reliably and then not have to worry about it for thousands of miles. I then get the benefit of no flats (I haven't flatted a tubeless tire requiring me to put a tube in ever on any bike, knock wood), lower pressures, more grip etc. These are real world benefits I've experienced for years. I will never ride tubed setups again on any bike, that's how much I personally like tubeless.

DaveSSS 

I used the Silca calculator with a 160lb rider + bike and 28mm tires and came up with 75 front, 77 rear. That's very close to what I've been using. I put 5 psi more in the rear tire than the front and I've run as low as 70 in the front.

Branko D

Well, I hit a pothole at speed just near home (heavy rain so it was more or less impossible to really see anything) and the front tire did a bang hisss which didn't seal. Vittoria speed tubeless are really slightly faster (just looking at some times uphill vs power confirms it) than tubed GP5000s but aren't exactly the ideal all weather all-arounder tire - it's got worse wet grip, too. Had the luck to have snow, heavy rain, mostly dry with wet patches and then torrential rain in the first rides on them and it shows.

Was a really good hit, though, the brifters slid down; normally I will at least unweigh the bars going over potholes or anything dodgy but it was hidden by a huge puddle of water so I just plowed into it, full force. Would've pinch flatted tubed tires, probably.
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tomato coupe

Not necessarily -- it depends on the surface.

rubiksoval

Absolutely not. I weigh 74 kg and have pinch flatted half a dozen times trying to ride anything at or below 90. Potholes are a real thing around here, as are rocks from washed-out driveways. 95 is about as low as i will knowingly risk.

Hiro11

The pressures I run on my primary bikes, all of which are set up tubeless. I weigh about 165. I check the pressure sometimes with an SKS digital gauge but I generally just go off the gauge on my pump (a Topeak Joe Blow Pro Digital, awesome pump BTW).

Road, currently 28mm GP5000TL: 75-80
Cross, currently 32mm Gravelking slicks (these on on fat hookless rims and measure out to 35mm): 40-45 (caveat: new bike, haven't ridden much)
MTB, current 2.25 Maxxis Ardents: 22-24
Gravel, currently 50mm Gravelking SKs: 30-35
Fat, currently 5" Jumbo Jims: 15 trail, 8ish snow.

The Silca tool's recommended pressures are significantly higher than I like to run, maybe they're talking tubed.

colnago62

Tire pressure on the track is usually much higher.

Sy Reene

Hmm, thought I'd take what you told us and check it out. Below has what I got using the Silca calculator (pro version) and 185lb total rider+bike weight. I indicated the surface types that I guessed. for reference, Silca's description of these are here: https://cdn.shopify.com/s/files/1/03...Guide.pdf?8341

Road, currently 28mm GP5000TL: 75-80; Silca = 77psi (using "Worn Pavement / Some Cracks)

Cross, currently 32mm Gravelking slicks (these on on fat hookless rims and measure out to 35mm): 40-45 (caveat: new bike, haven't ridden much); Silca = 41 psi using Type3 Gravel and 35mm WAM you provided

MTB, current 2.25 Maxxis Ardents: 22-24. Silca = 16 psi using 58mm on 26" wheel and Category 4 Gravel

Gravel, currently 50mm Gravelking SKs: 30-35 -- Silca = ~26psi; Using Type2 Gravel

Fat, currently 5" Jumbo Jims: 15 trail, 8ish snow. Not available in Silca tool

Psimet2001 

Man - not going to start the morning off with an argument but there's a lot of BS floating around in this thread. Stop with the "everyone", "no one", "never", etc. The longer you do this the more you'll watching things change and realize you were wrong before.

Flats - some people get them more than others. Period. This BS on pinch flats I've been seeing - I've ridden for years at or just below 100kg. I've done it one 23's at 116 psi and I've done it on 25's at 95 psi. without a single pinch flat. Yet I can fix 20 pinch flats a day in the shop. Some people just lead ass it over obstacles. I've went a couple of weeks trying to drop the pressure as low as I can until I have an issue....because I can. Finally tore the valve off a tube during a ride, "That was too low". That was roughly 80 psi.

Your data point and my data point aren't meaningful in the grand scheme.
For everyone saying someone is giving up just ton's of power by riding too high a pressure: I'll line of scores of riders who will run that higher pressure and still beat you. They will have their data and justification as to why they need to ride that pressure as well.

You should go back and find the pressure calculator I published out here like 13 years ago. I took data from Sheldon Brown and extrapolated some curves. A lot of people thought I was full of it at the time because the pressures were "too low". Now for the same size tire and rider those pressure would be considered too high. In 15 years we will all be headed back the other way. There's absolutely no point in getting bent out of shape over it. At the end of the day the pressure the rider is riding, if they are happy with it, is the correct pressure. I stopped answering "what pressure should I race on" questions at races a bunch of years back. Instead I simply start back with, "what pressure do you normally race on?" then I adjust what they reply with for the conditions.

There's exceptions to everything. If a rider shows up to cross and says they normally race on 50 psi....

I can still list a handful of riders who still win national championships on the track who will call you insane or tell you that you know nothing about racing on the track if you aren't running around 200 psi. That it's even "dangerous" to run less than that.

So stop.

Along the same lines as what I answer racers with - when it comes to tubeless, "how many flats do you have now? Do they bug you? meh - then give it a shot." or "oh not that many? not worth the hassle. It won't be life changing in the least."

At the end off the day none of this stuff doesn't make nearly as big of a difference as most of us hoped it would.

noodle soup

WTF does that mean?

Psimet2001 

I don't know. I am still trying to get my first coffee in.

DaveSSS 

With all this discussion about tire pressure, I decided to check the accuracy of my 30+ year old Silca pump. I have two brand new liquid filled 0-100 psi gauges on hand, so I made up a manifold with both gages on it and a presta valve stem. I found that both gages agreed within 2 psi at 80, but my pump mounted gage read about 8 psi low, so my 70 psi front tire was really only about 62. I now reference the 6 bar mark as 80. I'll now try an honest 70 front and 75 rear.

Hiro11

Thanks for doing my work for me, lol. I must have mistyped something previously, I only checked one bike. Looks like I'm in the range. OK, I officially like the Silca tool as it confirms what I've seen in my riding. One exception: there's no way in hell I would run 16psi in 2.25x27.5 tires on singletrack.

Hiro11

My old cheapo Performance Hurricane track pump (still has the best pump head ever) was probably 7-10 psi low compared to my SKS Airchecker gauge. My new Joe Blow is close enough to the SKS Airchecker that I just use its gauge.

Sy Reene

No worries.. I only double-checked because I feel Silca always comes in about 5% or so lower on PSI recommendation that I feel comfortable with, so to read a comment that it's higher had me curious.

I think they're taking their own findings (eg. the chart above in post 45), and building this finding into their calculator that eg. 10psi lower than ideal, only has a watt or 2 detrimental impact, and for most users they'll advise this. Maybe a TL bias assumption that pinch flatting is not a consideration as well. This is born out by entering in the test parameters that yielded that chart in the first place (190lb total weight, 26mm tire, new pavement), and you'll get a much lower returned value than the chart implies (eyeballing it looks like the low deflection point is about 110psi).

Hiro11

TLDR: Psimet doesn't like tubeless.

tomato coupe

Where did he say he doesn't like tubeless?

Hiro11

I'm reading between the lines. And being snarky.

jadocs

The SIlca website is bang on with the pressures I run.

Psimet2001 

Eh....

If I could actually say how I felt and not be labelled some sort of retro grouch or heretic then yes I would scream from the mountain tops that tubeless is immensely stupid... but even then I would have to preface that.

Tubeless is amazing and 100% worth it on fatbikes. The weight dropped, reduction of work involved in a flat, and the reliability makes it a perfect solution.

I can't imagine mtb with innertubes. Just doesn't make sense.

I feel the same about cross. If you can't figure out how to run tubulars then you need to be running tubeless.

It makes so much less sense for road that it's kinds ridiculous in my opinion. Sure everyone has their anecdotal justifications and reasonings that back up their own decisions on this. Keep them.

When someone who is enthusiast level or higher around here asks whether they should go tubeless it's always the same discussion, "you have a lot of flats now?" "No." "Then there's no reason."

Hiro11

I was just being snarky.

It's all personal preference. I personally like being able to run 28s at 77psi on a road bike without being slow, while enjoying what I perceive to be more comfort and more grip and without being worried about flats. I personally definitely would be worried about tubed 23s at 77psi on Illinois roads. I personally don't have hassles with getting a good tubeless setup quickly and find tubeless to be low maintenance once set up. These are all my opinions. Other opinions are just as valid as mine.