Yes, I recall the utter horribleness of 35 mm Specialized Fatboy 26” slicks pumped to the 100 psi or so on the sidewall label. On smooth pavement they were fine, but cornering on bumpy pavement had the rear wheel skittering around. And I wondered at the time why Spec 26 X 1” Turbos at about 22-23 mm and 100 psi felt so much smoother.
On Mon, Nov 3, 2025 at 1:55 PM Guy Jett <[email protected]> wrote: > In the olden days I always pumped my tires to the max listed on the tire > sidewall. In my ignorance that seemed acceptable. And it often was for > the 1 to 1-1/4 inch tires run at the time. In general, the higher the > pressure the better. > > I first encountered the idea of running at lower pressures through the > work of Frank Berto. His work documented lower pressures in terms of a > percentage drop for the tire height. Lower pressures were often advocated > as the actual weight of the rider was less on the front of the bike than > on the rear. See "Tire Pressure Take-Home" > <https://www.renehersecycles.com/tire-pressure-take-home/> on the Rene > Herse website for a summary. > > After many years of real world testing Jan Heine of Rene Herse (formerly > Compass Bicycles) demonstrated that running tires at lower pressures > actually made the ride both more comfortable AND with either no loss of > speed or, indeed, some slight increase in speed. Many of the articles at > the Rene Herse website document the science and the statistics behind this > research. He eventually published a "Tire Pressure Calculator > <https://www.renehersecycles.com/tire-pressure-calculator/>" yielding a > "soft" pressure and a "firm" pressure that were very near equal in > performance allowing some user flexibility. In contrast to earlier low > pressure recommendations Hene advocated for using the same pressures front > and rear as, under braking, the weight on the front could exceed the weight > on the back. Note that inputs for calculating these tire pressures are > bike-rider-gear total weight and tire width. One limitation is that tires > less than 25 cm (1-inch) width are not considered. Jan also make clear > that the recommendations are just good starting points for experimentation. > > Silca also has their "SILCA Pro Tire Pressure Calculator > <https://silca.cc/pages/pro-tire-pressure-calculator>" which calculates > pressures for narrower tires down to 20 mm. The inputs are also much more > complex where, in addition to total weight and width, the user is also > asked to input surface conditions, a qualitative "average speed", a "tire > type", and your front and rear weight distribution. In general these > recommended pressures are slightly to significantly higher than the Rene > Herse recommendations. The science behind Silca's calculation is not clear. > > I currently use the Rene Herse calculator to run my AHH with 650B x 38 > tires at 40 psi, and my Raleigh Competition 27 x 1-inch fronts at 74 psi > and 27 x 1-1/4-inch rear tires at 47 psi. > > > On Mon, Nov 3, 2025 at 9:15 AM Patrick Moore <[email protected]> wrote: > >> I’ve been thinking about tire pressure recently, as I recently rode with >> a friend who insists on pumping his 38s to50 psi or more, while I pump my >> 28 mm (actual) Elk Passes to 55F/60 rear, my 32 mm Stampede Passes to >> 50/55, my 41 mm Naches Passes to 35/40, and my 54 mm Thunderburts at about >> 18 psi. I’ve been finding that the SPs might do better at 45/50 and the NPs >> at 30/35. I’m a bit more than 160 and the bikes with usual luggage weigh >> (guessing; first number ready to ride but no luggage, second is guestimate >> with usual luggage (Gofast: 18/19; Roadeo: 20.8/21.8; Errand with NPs >> 26/30; road bike for dirt 30.5/33.) >> >> So it was fun to enter the numbers into the RH pressure calculator and >> find the following; the second set is my actual range. Rider + clothes, >> let’s ballpark at 165. >> >> RH Historical Actual >> EPs: 60-75 / 55-60 >> SPs: 49-60/ 50-55 >> NPs: 35-43/ 30-40 (I often carry heavy loads on this bike, mostly on rear >> but sometimes adding weight in front). >> TBs: 27-33 / 17-20. >> >> Other pressures: 72 mm WTB Rangers: 13-15 psi; 22 mm Spec 26x1 Turbos, 22 >> mm Conti GPs, 22 mm Mich Pro Race: 80-90. >> >> I’ve been using these pressures for years on surfaces ranging from >> dinner-plate smooth to rough gravel and, on pavement, often over 8” or >> wider pavement expansion cracks. >> >> I *never, never, never, never* pinch flat; the only time I’ve pinch >> flatted in the last 40 years was when I deliberately ran a 22 mm actual >> Specialized 26 X 1 Turbo (200 grams) at 80 psi in front into a pile of >> large gravel to see what would happen. Yes, I got a pinch flat. >> >> I’m curious to hear from others what I’m doing wrong. >> >> https://www.renehersecycles.com/tire-pressure-calculator/ >> >> -- >> >> Patrick Moore >> Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum >> >> ------------------------------------------------------------------------------------------------------- >> >> Executive resumes, LinkedIn profiles, bios, letters, and other writing >> services >> >> >> ------------------------------------------------------------------------------------------------------- >> >> *When thou didst not, savage, k**now thine own meaning,* >> >> *But wouldst gabble like a** thing most brutish,* >> >> *I endowed thy purposes w**ith words that made them known.* >> >> -- >> You received this message because you are subscribed to the Google Groups >> "RBW Owners Bunch" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion visit >> https://groups.google.com/d/msgid/rbw-owners-bunch/CALuTfgsXeGfGUqPKkc%2BW7gt6kuGBVJ0VNLx2TgAr3xZAfmzk4Q%40mail.gmail.com >> <https://groups.google.com/d/msgid/rbw-owners-bunch/CALuTfgsXeGfGUqPKkc%2BW7gt6kuGBVJ0VNLx2TgAr3xZAfmzk4Q%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/rbw-owners-bunch/CAMHQv6UNBEbyx52XJbFWfHP1Anw1Nf-Qxgsa6S783KBGp%2BEssg%40mail.gmail.com > <https://groups.google.com/d/msgid/rbw-owners-bunch/CAMHQv6UNBEbyx52XJbFWfHP1Anw1Nf-Qxgsa6S783KBGp%2BEssg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- Patrick Moore Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum ------------------------------------------------------------------------------------------------------- Executive resumes, LinkedIn profiles, bios, letters, and other writing services ------------------------------------------------------------------------------------------------------- *When thou didst not, savage, k**now thine own meaning,* *But wouldst gabble like a** thing most brutish,* *I endowed thy purposes w**ith words that made them known.* -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/rbw-owners-bunch/CALuTfgtGWPjqo7vfXq81BBA5ZfNZVDuyhGAx0g2OZszHVZJCyQ%40mail.gmail.com.
