TiHabanero

In 1998 I had immediate need for a tire and 25mm was not available so a 28mm was installed on both wheels. Have been riding 28mm since that day. They are far more comfortable, wear better, and don't seem to affect top speed at all. Sprinting, yes, there is a weight difference that can "sorta" be felt, but mostly I think it is the increase in sidewall height causing more flex. 2000 was my last of racing so it simply does not matter anymore, and honestly it didn't then, either as I am a 230 pound wonder anyway.

caloso

The biggest that fits.

Sy Reene

It seems a lot of BF is now on a bandwagon that's claiming comfort is king. No longer is priority performance, but cushiness. 15% drop used to be determinant of 'proper'. Now we hear that 100psi for tubed 25mm tire is overkill? (though it probably is for a front tire, I think most 15% drop calculators ask for about 100psi for a ~160lb rider).

big john

The difference being that $70 could be a recurring expense due to flats. Don't know if these tubes can be patched but it's hard to patch the latex ones.

mstateglfr 

Yeah, not sure. I agree comfort is king is an often repeated mantra on here. But it's how I choose tires offline too.

I am typically the tallest and heaviest rider in any given group, so I cant say how tire pressure is figured for many riders. I usually overinflate compared to most anything I see here, but I chalk that up to weight difference.

If there rolling resistance between a thin and wide tire at proper pressures is basically zero and the wider tire weighs only 25g more, there really isnt a downside to using it. I think that's much of why this trend has been embraced so much.

ThermionicScott 

You are easily impressed by charts and graphs. Where is the one for energy lost in the rider's body at various pressures?

In other words, this is a classic "you manage what you measure" situation...

caloso

A 3mm wider tire might be the difference between being completely beat up or relatively fresh after 3 hours in the saddle. I know that's definitely the case on our NorCal pave'.

Sy Reene

But it's comments like these that I find interesting. 3 yrs ago, nobody was complaining about how beat up they were from their tires being inflated to 90+psi, now it seems like the BF wisdom is that pressures like this are insane.

ThermionicScott 

Sure they were! It was a major reason that the cycling market pivoted from road bikes in the 1970s to MTBs in the 1980s. Those hard skinny tires. The difference now is that the effect is finally being quantified and so it's not as "un-manly" to discuss comfort on the bike.

HTupolev

If a lack of compliance is resulting in discomfort, the energy being spent making you uncomfortable is coming out of your forward momentum. Even ignoring the performance affects of being fatigued, pumping tires comfortably isn't just about comfort for the sake of comfort.

Where are you getting those numbers? A 160lb road rider tends to me somewhere in the ballpark of a 180lb bike+rider. If we assume a 55/45 weight distribution, that's about 100lbs on the rear wheel and 80lbs on the front. If we target 15% drop by referencing the Berto chart for a 25mm tire, that's a little under 90PSI for the rear wheel and a little under 70PSI for the front wheel.

15% drop was never "proper", it was a rough rule of thumb to establish a starting point. Obviously some folks treated it like a hard rule, but that's not much different to how the same happens with any rule of thumb, like some people think that every bike should have the fore-aft set to exactly KOPS.

A lot of things played a role, including posture, gearing, and braking. Don't forget that in the early 80s it was still common for road bikes to fit tires over 30mm wide.

That was a time when everyone was stuck on single-pivot calipers even though vastly better brakes had been available for many decades, and if you wanted an upright road bike, your option was a racing bike with turkey levers and stem shifters. The technology of the day allowed road bicycles to be fantastic machines, but the fashion of the day resulted in no shortage of silly nonsense.

BengalCat

IMO for the majority of riders, the larger size is better when choosing between the same model of a road bike tire. Faster, softer ride, better traction, and cornering. As for PSI, don't trust forums general simply because as you will see if you read enough the pressure advice is all over the place. The best I have to offer on that subject is to stay within the minimum and maximum manufacturer specifications. Most people, I think would agree that whatever PSI you choose that has less in the front than the rear is usually optimal.

Jno

This site has data that is no longer completely current but I found it helpful a couple years ago, and maybe it or an equivalent one has been updated to reflect the move to wider rim widths https://www.bicyclerollingresistance...d-bike-reviews

Sy Reene

I think that as recent as this century's first decade, the hard skinny tires were indeed that.. ie. 23mm or less tires that were inflated to 120psi (or more) was very common

I don't disagree with the notion of comfort/fatigue eventually factoring into performance on longer rides. I think though that what I've noticed is that evidently many riders were always fatigued and beat up by their bike tires before the more recent notion to go wide and soft. For some reason though, it seems we're only hearing a lot about this now, because even a few short years ago, I don't recall as many talking about it.

FYI, I typically use the dorkypants calculator (the middle one on the linked page below). As a starting point, for myself I use the 45/55 result to set my front tire pressure and the 40/60 result to set my rear tire pressure. However, I do generally adjust to fit within tire sidewall ratings (example: calculator gives me 78psi front result at 45/55 for 25mm tire but my 25mm sidewalls indicate 100psi as minimum -- admittedly I do cheat a bit lower than this though.)

Bicycle tire pressure calculator

ThermionicScott 

Skinny high-pressure tires feel faster and tended to do well on drum tests, so they've long been assumed to be the best for performance bikes. People have still been muttering about the ride for a long time, even if you weren't aware of it.

Sy Reene

I know they complained... but the where the bar (no pun intended) is set keeps changing.. When many went to 25s and dropped their pressures by 20 psi, there was much rejoicing. And now that's still too much and the bar is lowered again.

FWIW, I think maybe much of this has to do with the wheel makers. I don't think they publish any performance results that back this up, so maybe this is because the recent wider carbon rims are just too weak to take higher inflations, or tires will blow off the rims if there's too much air in them?

I notice that HED's recommended inflation is a formula of Rider weight (kgs) x .90. IOW, a 165lb rider should start with 68psi inflation.

Enve is a little higher for their guidelines, but they max out at 95psi (25mm) as allowable for anyone 240lbs or heavier. (80psi for 28mm). These are way off from any tire drop calculator -- not even close

ThermionicScott 

Why do you assume there's "a" bar? Formulas and specs are nice for OCD folks, but the truth is that as long as the tire doesn't pinch flat or blow off the rim, you're good. For a lot of cycling history, most pumps didn't even have gauges. They didn't need them.

noodle soup

+1

A decade ago we didn't have a choice. There were no wide high-performance tires. Now that we have many wider options, I use 30mm Schwalbe G-One Speed tires @60/55psi.The ride is smoooth as buttah.

Carbonfiberboy 

Oh boy, oh boy, another tire pressure thread! I weigh 145 in summer, still run 23mm, mostly smooth roads, some chipseal, 80 front, 100 rear, 4000 IIs. I like the aero on 23mm outside deep-ish rims. Old carbon bike, don't notice vibration particularly. Definitely a fast, smooth combo, bike, tires (latex tubes), wheels.

The silly chart . . . People tend to look at the RR going straight across. But no one does that. Go diagonally - so 100, 80, 60, because that's what people of my weight run. If you run 100 in a 28, you'll get a worse ride than the same pressure in a 23. Duh. A major factor in a smooth ride is the length of the contact patch.

If you want to know what to run and have a PM, do an out-and-back on a bit of typical smooth and chipseal holding the same speed, watch your meter. Take a couple candidate tires, pump and pressure gauge. Always good to get more practice changing tires on the road.

noodle soup

I am curious to hear some of these reasons. Is the wheelset you are using incompatible with tubeless?

Gconan

28mm for sure. I have a 25/28 5000 combo on one bike and just put 32mm on another. Of course mine are tubeless and comfortable. Bigger is more comfortable, and so is tubeless.

noodle soup

Tubeless can be more comfortable, but the OP isn’t concerned about comfort.

FlashBazbo

"To simplify the thread" and to keep this thread from becoming a rabid anti-tubeless / anti-tube festival, I decided not to talk about the reasons. (There are plenty of those threads elsewhere.) I could anticipate the potential thread-jack.

But no, the wheelset is not incompatible. It's a Mavic UST wheelset.

noodle soup

It didn’t work. Now people are just talking about inflation.

Gconan

28mm. Tubed.

sfrider 

My experience with tubed GP4000S's though is that even slightly deflating 28C's made them noticeably draggy. I settled on 25C back when I did that test and the 28C's are still in a bin somewhere. I didn't try latex tubes, just plain butyl ones. I ended up going back and forth between 23C and 25C over the years. There was definitely a noticeable penalty running 25's at a lower pressure, but I think they rolled the same (and the 25's still felt more pliable, but trivially so) at the same 100psi or so. But running them at the same pressure also seemed pointless, why not just use 23's in that case... hence the going back and forth. *shrug*

This is very different from tubeless, where on GP5000TL 28C's reducing air pressure doesn't affect resistance nearly as much, at least if we're talking 10-20 psi around the 70 mark. The main difference I've noticed is they get louder when deflated but that's a very minor point. Same as tubed WRT to road noise.