Patrick your story reminds me of how my brother would recount all his training in the Air Force to work on F-16's and later on commercial jetliners. When asked how such and such "really works", there some point when all you can say is "it's PFM". Pure f'n magic. Beyond explanation and reason. Ahahahaahahaaaa ! I love that term , as when it comes down to everything of this world and how "everything works", is to me ... P F M !!!! In a wondrous way !
On Monday, June 8, 2020 at 7:40:30 PM UTC-4, Patrick Moore wrote: > > The Franklin sounds intriguing; can you post a photo? > > Your experience may well be due to tubing differences; I know that my > Matthews, built from thinwall, heat treated stuff compared to the > excessively stout tubing of the original Fargo, and with a delicately > shaped "French" curve instead of the Fargo's girder legs, rolls smoother > over small bumps -- washboard, eg -- with the same wheels and tires. But > tires and casings and widths and pressures can also cause this sort of > difference. > > My own experience with tires fat and skinny -- from 19 mm (labeled; this > was at a time when I naively thought (1) skinnier was faster; (2) labeled > width was the actual width, and (3) labeled max press was the best press) > to 65 mm actual width (60 mm Big Apple regulars on 50 mm SnoCat SLs) -- is > that tire pressure, casing, and width all play a tortured, complex, and > often inscrutable ballet or fugue or minuet together, and that -- wala!! -- > sometimes fatter tires feel **harder** than skinnier tires, and sometimes > thinskin, supple tires feel **harder** than thickwall utility tires. I'll > explain. > > I'll start with an anecdote. For years I rode 26" X1" (559 X 22 mm actual > on my skinny rims) Specialized Turbos at 110 psi, later, wising up, > reducing that to 80/90 f/r. **These felt cushiony and smooth** as long as > you were riding over chipseal or small cracks and not our 6" to 8" > expansion cracks. OTOH, 35 mm Fatboys pumped to sidewall max (try that with > a Blackburn Airstick, 1990 model!) bounced you around on all but the > slickest pavement. Even reducing the Fatboys, and later similarly wide > Kojaks to 50 psi: sure, the 35s (32 actual) handled big cracks better, but > over rough, worn pavement? Nope, the 22s were at least as smooth if not > smoother. > > Reasons? Well, suppleness for one thing, but also, tire pressure tradeoff. > The 22s at ~90 were so skinny, as well as supple, that they "gave" at each > little bump. The downside? Pinch flat and rim damage if you hit something > too big too hard. I personally am a delicate rider and never got pinch > flats on those tires, even with 40 lb rear loads (broke a spoke or 2, > though, with aluminum nipples and Revolutions). The Kojaks were smoother > than the Fatboys, but to get the same cush, you had to reduce the pressure > to almost -- **almost** -- wallowy softenss. 32 mm Paselas, light 240 > grams, even worse; soft and they bounced; no bounce, and they jarred. > > I recall swapping the 60 mm Big Apples, thick stout things, for very > supple Furious Freds (60 mm/50 mm, 900 grams versus 360 grams. 800 grams > for the BA "lite" model) and being disappointed that the FFs seemed to be > as harsh over bumps as the BAs. The reason was that, with the paper-thin > sidewalls, I had to pump them to at least 18 psi, while I often rode the > BAs with thicker sidewalls at 15. The balance between "soggy" and "harsh" > was a difficult one to achieve. > > I switched to 60 mm Big Ones -- 90 grams heavier than the 50 mm FFs at 450 > grams. Again, pump them hard enough to not lose control on fastish pavement > corners, and they are surprisingly harsh over bumps -- the minimum is about > 18 psi, tho' I usually run them at 19-21 for less wallowing in pavement > corners. > > Upshot of all this driveling: you can put fat tires on a bike and pump > them to the minimum psi to prevent wallow or bouncing, and you may find > that this minimum pressure makes them harsher than you'd think, to the > point where, in certain situations, a 32 mm supple tire at a pressure just > high enough to avoid bouncing or pinch flats actually feels softer over > certain bumps than a fatter tire at a lower pressure. > > > -- 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 rbw-owners-bunch+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/2b485b0f-8b31-4dec-bd1c-303faacd5913o%40googlegroups.com.
