I do appreciate the pictures on Rivendells site that shows the calipers, tire and rim all in one shot, makes it a bit clealer and seems a simple system for at least having some baseline. On Jun 11, 2014 1:13 AM, "ted" <ted.ke...@comcast.net> wrote:
> More or less, and whether 2mm out of 32 should be called a 6% or a 12% > effect it is certainly 2mm and if that matters to you then it matters. > I tend to go overboard on wishing folks would provide more detail so maybe > I am nuts here, but I wish when tire widths were stated the rim they were > measured on was also given. I sort of wish the convention was to state bead > to bead separation with the tire flattened out instead of mounted width. > > On Tuesday, June 10, 2014 9:27:22 PM UTC-7, Anne Paulson wrote: >> >> So you're saying, then, that low-pressure tires compress not because the >> air pressure inside them changes, but because the tire deforms in response >> to a force and the air pressure inside it remains more or less the same. >> You say it behaves like a spring and we should analyze it like a spring. >> >> So then one would like a tall tire (with a lot of drop) because it would >> have lots of room to deform and soak up bumps, but then then the tall tire >> needs to be wide for good cornering. And one would like a tire with a >> supple sidewall because that would also contribute to the tire deforming >> instead of bouncing when it encounters bumps. >> >> That sounds convincing to me. >> >> But, to return to the issue of whether the Cypres is smaller than other >> tires made by Panaracer that are called 32 mm tires: I say yes, because (1) >> Panaracer marks Paselas as 32 mm tires and Cypres as 30 mm tires and (2) >> when brand new, flat folded Paselas are wider than flat folded Cypreses. >> >> >> On Tue, Jun 10, 2014 at 9:02 PM, ted <ted....@comcast.net> wrote: >> >>> The derivate of contact patch area with respect to "drop". >>> >>> I think the support force is roughly psi times contact patch area. I >>> think that though the internal pressure may increase slightly that effect >>> is negligible because the change in tire volume is a tiny fraction of the >>> total. I think the spring rate is psi times delta area divided by delta >>> drop. I think the relationships between contact patch area, tire width and >>> drop are a bit complicated. I suspect spring rate dependence on width is >>> closer to linear than the width squared dependence that is implied by >>> assuming it varies with cross sectional area (which is what I think you are >>> suggesting). So for cush I think it is closer to a linear linear dependence. >>> >>> For pinch flats I think you get a linear increase in spring rate from >>> the width and another linear increase in allowable deformation due to the >>> hight that goes with the width. So that would suggest a scale factor >>> squared dependance on that front. >>> >>> My experience of late has been that I pick the pressure based on ride >>> and handling. Pinch flats just haven't been a problem for me. Of course I >>> don't assume that is the case for everybody. >>> >>> >>> On Tuesday, June 10, 2014 7:14:42 PM UTC-7, Anne Paulson wrote: >>> >>>> The effective spring rate is going to depend on volume, isn't it, >>>> because the volume says how much air there is and that determines how much >>>> compression there can be? And the contact patch is going to depend on >>>> diameter, isn't it? >>>> >>>> The derivative of the contact patch with respect to what? >>>> >>>> >>>> On Tue, Jun 10, 2014 at 6:34 PM, ted <ted....@comcast.net> wrote: >>>> >>>>> I would think we care about effective spring rate (cush) and how much >>>>> additional travel is possible before getting a pinch flat. Aren't those >>>>> driven by the contact patch size, its derivative, and the height of the >>>>> tire? How does cross section area (or volume) drive those? >>>>> Are you sure this is a diameter squared dependency? >>>>> >>>>> On Tuesday, June 10, 2014 5:31:44 PM UTC-7, Anne Paulson wrote: >>>>> >>>>>> It's 6% in diameter, but that makes 12% difference in volume, which >>>>>> is what we care about. >>>>>> >>>>>> >>>>>> On Tue, Jun 10, 2014 at 4:56 PM, Deacon Patrick <lamon...@mac.com> >>>>>> wrote: >>>>>> >>>>>>> That's about a 6% discrepancy, which certainly seems reasonable >>>>>>> given different rim widths and tire stretch. >>>>>>> >>>>>>> With abandon, >>>>>>> Patrick >>>>>>> >>>>>>> >>>>>>> On Tuesday, June 10, 2014 4:52:31 PM UTC-6, Anne Paulson wrote: >>>>>>>> >>>>>>>> If you order some of Jan Heine's tires, be aware of a size >>>>>>>> discrepancy. >>>>>>>> >>>>>>>> I just got a couple of his Grand Bois tires, which are sold as 700 >>>>>>>> x 32mm. I knew they were made by Panaracer, and I have used the >>>>>>>> Panaracer >>>>>>>> Pasela 32mm and the Jack Brown 33mm tires, so I figured I knew what to >>>>>>>> expect. When the tires arrived, they looked narrower than I expected. >>>>>>>> Then, >>>>>>>> when I opened them up, they were labelled 700 x 30. Then, when I >>>>>>>> mounted >>>>>>>> them on my Mavic Open Pro rims, they measured 30mm wide. >>>>>>>> >>>>>>>> When I asked Jan, he explained that he has a different system of >>>>>>>> measurement, and according to his measurement system (mounting them on >>>>>>>> some >>>>>>>> rim or other) they measure 32mm. >>>>>>>> >>>>>>>> So, expect the Grand Bois tires to be narrower than other tires >>>>>>>> sold with the same width. >>>>>>>> >>>>>>>> -- >>>>>>>> -- Anne "Standards are good, everyone should have one" Paulson >>>>>>>> >>>>>>>> It isn't a contest. Enjoy the ride. >>>>>>>> >>>>>>> -- >>>>>>> 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-bun...@googlegroups.com. >>>>>>> To post to this group, send email to rbw-owne...@googlegroups.com. >>>>>>> >>>>>>> Visit this group at http://groups.google.com/group/rbw-owners-bunch. >>>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> -- Anne Paulson >>>>>> >>>>>> It isn't a contest. Enjoy the ride. >>>>>> >>>>> -- >>>>> 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-bun...@googlegroups.com. >>>>> To post to this group, send email to rbw-owne...@googlegroups.com. >>>>> Visit this group at http://groups.google.com/group/rbw-owners-bunch. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> >>>> >>>> >>>> -- >>>> -- Anne Paulson >>>> >>>> It isn't a contest. Enjoy the ride. >>>> >>> -- >>> 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-bun...@googlegroups.com. >>> To post to this group, send email to rbw-owne...@googlegroups.com. >>> Visit this group at http://groups.google.com/group/rbw-owners-bunch. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> >> >> -- >> -- Anne Paulson >> >> It isn't a contest. Enjoy the ride. >> > -- > 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 post to this group, send email to rbw-owners-bunch@googlegroups.com. > Visit this group at http://groups.google.com/group/rbw-owners-bunch. > For more options, visit https://groups.google.com/d/optout. > -- 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 post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
