Really? 57%?

I've got GP4000S's on my road bike and I don't think I notice any difference.

I think those are lab test, thus, no valid.

If you're trying to go fast, Schwalbe is probably a bad idea. These tires are very durable and puncture-resistant, but they're also heavy and infamously rigid. If you want fast and supple, try Panaracer.

I'm not convinced skinny tires are that much faster than fatter tires for commuting purposes. The rolling resistance of a 28 mm tire isn't going to be significantly greater than a 23 mm tire, all other factors being equal. I rode on 28 mm tires for a few years before going to 37 mm last year. I ride just as fast as I did before, only now the ride is a lot more comfortable, and I never get flats, possibly because of the lower tire pressure.

I doubt all Schalbe tires are slow and rough.

Tabarnak......

I've got 28C Vittoria Randonneurs on my bike - but they're super narrow as 28s go. I can't even use a 28C tube in them - I use a 23/25 tube and it fits perfectly. They're much narrower than the Kenda Kwests I used to have on the bike, even though those were also 28C.

Good tires - highly recommended. Extremely durable (not a single puncture since I started using them), and they also roll pretty darned well.

Don't forget to include the weight of the bike. If you're 140, the baggage is 20 and the bike is 25, that's 185. Around 60% of that (111) is on the rear wheel. So according to the chart, that 28mm tire should be at around 82 psi, which sounds totally reasonable to me. Pump it up to 85 or 90 if that makes you feel safer, but you'd be fine at 80.

+1

No. 1.

P.S., your wife doesn't read BF, right?

Thanks! I did forget to include the bicycle weight. That means, though, that the front gets about 75 lbs. According to the chart, that's less than 60 psi.

I currently have about 90 psi on both front and rear. I'm fairly comfortable with that setup, but should I lower the front?

If you want. I'm 160 lbs (bike: ~30) and use 65/80 in my 700x28s.

You mean you are 160 lbs excluding the bike? I'd be worried about a pinch flat if I had 65 on the front. Does it depend on the tyre, too?

Gator skins in a 700 / 28 give a nice ride an are on the shinny side of 28's . I have been riding them most of the summer in the city and ha be had no flats. But they are pricy

Yep, roughly 160 with my clothes and shoes on. The front tire feels a little squishy when I'm sprinting or climbing out of the saddle, but I haven't had a pinch flat for a long time. (And that was when I was brand-new to road bikes and didn't know to check the pressure often. )

P.S. That said, I wouldn't go any lower than what the chart in the BQ/Frank Berto article suggests. It's a minimum pressure for performance and comfort that works if you check your pressures often, and adjust upward if real-life experience suggests it.

Tire weight - makes a diff for me. besides the 'feel' of the tire, poppin up small rises, startups and any accels just go easier with a lighter tire.
Another effect of a lighter tire is generally a more supple casing. More supple from lighter weight, higher thread count, means less bouncing over road irregularities.
SOme times you can make a real find.
My first week on my new commuter/shopper/errand bike (replaced a very tired and now broken Fisher Tassajara convert)- '06 Spec Roubaix - was 2 days on the 23s I had on the Ritchey OCR Aero Pros I had on there... Fast, nice, but a bit too sporty once I got the rack and bags on it.
I had ordered a pr of Avenir Discovery 28c tires from Amazon, $18 ea, shipped free with 'prime', just to see what a wider tire on this bike might feel like.
So when they came in, I put them on a PerfBike Titan wheelset I had hangin around and slapped them onto the Roubaix. Rode the next 5 days on them, commute and shop. Very Nice! After experimenting with pressure, I ended up airing them at 70 lbs frnt and 75 rear, for a great compromise of feel and comfort. I'm 160 lbs. But even for much bigger riders I think these would ride very nice in the 80-85 lb range.
I weighed the Avenire Discovery at 296g - 20g lighter than the 'spec'. I believe this is the Kenda K176 tire with a 60tpi casing.
A great deal at $18 each - nice tire!
went back to amazon, today, to buy a few more - price went up to $23 ea in the 2 wks since I bought my first pr. Still a nice tire at a good price, but maybe I'll wait until they drop price back to the teens...

I bought a gatorskin 700x25 once and I really didn't like it, the most flats I ever got with a tire (by far) and I barely got 3000 kms out of it. I know a lot of people like the gatorskin so it must be me but still, never again...

I found another lbs about 20 kms from where I live and got there yesterday. I talked for a good half hour with the guy and I was very impressed. Very knowledgeable guy and when he didn't know he just said so. He gained a new custommer.

If the guy who sold me the schwalbe deltacruiser had take the time to ask me a few questions he probably wouldn't have sold me those tires in the first place. I finaly bought a vittoria rubino 700x25 (I already had a vittoria Rubino 700x23 on the front) that I will put on my rear wheel and I'll put back my previous tire on the front. So I'll be running on Vittoria Rubinos, 700x23 in the front and 700x25 in the back. Since I ride this bike it'll be the first time that I have the same tires on both wheels!!!

Was it the Hardshell gatorskin or regular? I keep hearing and reading how puncture resistant gatorskins are, but did you know the PRB only goes in the very center of the tread? Hardshell is shoulder to shoulder. So the standard version you will get punctures if you lean in you turns and ride over whatever.

Yah. Marathon Supreme and Kojak come to mind...

I ignore that chart. It doesn't take into consideration the type of tire. I got into a nice flame war with another poster over it because he felt that chart and his personal experience were superior to the tire manufacturers' knowledge. I have two sets of 700x28 tires;one marked 85psi max,the other marked 110min-125max. I use the 85's on a hybrid,I use the others on a road bike. If I followed that chart,my road bike would be pinch flatting and would handle like crap. FYI,I run 2" tires on my Safari pumped to the max @70psi,and have had no issues with handling,comfort,or failures. Different tires are made for different uses,even if they are the same size.

Chart doesn't take into consideration the tires, the rider, the road.
At your weight, riding most 28c tires at 60 would not be a big deal.
Ideally one wants the tire firm enough to not have too much flexing (hysterisis) which builds up internal heat, and not so firm that the tire boucnes thru road irregularities. The 'irregularities come into play even on seeemingly smooth road surfaces. SO pumping until the tire is rock hard is counterproductive and slow. You can do it by 'feel' if you have enough comparison to other wheels/tires or you can be very pragmatic and do coast-down tests at different pressures. And then makes decisions on speed VS comfort.
A 28 ridden at 70 lbs will feel very much like a 23 ridden at 90, given the same level of tire construction.
AT 160 lbs, I find th best balance on the 28 is 70frt75rr for me.
Pinch flats at normal pressures for a size can mostly be attributed to rider inattention. Not lightening when going over surface joints or other edges is all on the rider. If a rider is hitting an edge hard enough to cause a pinch flat, there's a good chance they;re also doing damage to the rim.

I don't know which one it was, I think it was the regular but still, I bought many tires at half the price of the gatorskin with better mileage and less flats.

Thanks for the info. Makes me wonder how the tyre manufacturers determine the minimum air pressure. Mine says 100, which is way higher than 60-70. I do feel the ride to be too harsh with 110 psi, which I used to have. I will try and experiment with different values to find the "sweet spot" for me.

The recommendations may be limited in their goals. Minimum is probably set to prevent dissatisfaction from under inflation. Maximum may be set for safety, but I read that the makers test their tires at twice their own recommended pressures. In other words, I don't know! :-)

That's always been my assumption, but if anyone has better info, I'm all ears. My aforementioned Pasela 700x28s have the commandment "Keep Inflated 735 kPa (7.4 bar 105 psi)" on them, which isn't super-clear as to whether it's the recommended minimum or maximum. Seems too high for my situation either way.

You changed the model from Durano to Delta Cruiser.
Durano is a tough but efficient training-grade tyre.
Delta Cruiser is an entry-level utility tyre, lower grade than Marathon.
DC 28mm almost twice the weight of Durano 28 mm and half the price and the thread count is 50EPI vs 67.

Given the same model of tyre, a wider tyre will be have lower rolling resistance AT CONSTANT PRESSURE.
Narrower tyres are usually run at higher pressure which can reduce rolling resistance.
Narrower tyres are lighter in weight which makes them accelerate better and have lower air resistance.
The dominance of rolling resistance (RR) vs air resistance (AR) is worthy of note.
On a graph of resistance vs speed, RR is a straight line, as speed doubles, RR doubles.
AR is proportional to speed squared, as you double speed, AR quadruples (x4).

When you are cruising along, RR is the dominant form of resistance and wider tyres are more efficient.
When you are pushing hard, like in a time trial, AR is the dominant drag force and narrower tyres are more efficient.

Jobst Brandt used to be active in rec.bicycles and was a wealth of information. He designed the Avocet FasGrip tires in the 80's (or was it the 90's?) which were made by IRC (a Japanese company). IRC stopped making bike tires a while ago. Jobst was the source where I heard that manufacturers test their tires at double their pressure, which is why it's probably safe to run them above their recommended maximum pressures. He didn't say it's a good idea, though.

Unfortunately, Jobst is now disabled by an aneurism or something like that. I don't remember. He's not able to post on the internet any more.

As I remember -- and someone please correct me if I'm wrong -- the FasGrip tire was the first smooth-tread tire. Jobst made a machine that tested rolling resistance and determined that tread pattern was unnecessary on bicycle tires where the bike was not going on loose surfaces.

MichaelW, I have read air resistance makes it such that power required on a bicycle is proportional to the CUBE of speed, unlike in a car. I saw the explanation for why it is, but I didn't understand it, not having enough engineering and fluid dynamics background. In any case, you make a good point about rolling resistance being important at low speeds and that eventually, air resistance becomes the dominant force at a certain speed. Of course, what that speed is is very variable.