Unless nobody ever looks at it, I'd argue that improving aesthetics **is** a practical purpose. I also suspect that in many situations an extra 1/2 lb in the total bike + rider + stuff (e.g. bags, tools, spares, cloths, water, food, etc) weight is imperceptible, and therefore not a practical (as opposed to theoretical) detriment.
On Tuesday, August 4, 2020 at 6:58:58 AM UTC-7, Patrick Moore wrote: > > You are right that a second top tube will do something structurally; > there's no avoiding that, and I overstated my own case. But my point is > that for anything but a very large frame, or for a frame to be ridden by > someone exceptionally heavy, there's no **practical** purposes served by > the added tube. > > Still, that Atlantis frame does look very pretty; far nicer IMO than the > other models with 2 top tubes; they got the mix of straight and curved just > right. > > On Tue, Aug 4, 2020 at 12:07 AM S <sbl...@gmail.com <javascript:>> wrote: > >> As is my habit, I overstated my case. What I said is technically true, >> because of physics, but I can believe the real world effect might be >> negligible. >> >> In the back of my mind was the side discussion on here or iBob about the >> supposed deadness of the Surly Cross Check frame. Some forum members -- me >> included -- insisted the frame was a dog, no question, while others >> disagreed. As it turned out, those in the former camp had the 56 and those >> in the latter camp larger sizes. The theory was floated that maybe the >> frame "opens up," that is, flexes more, in a good way, in the larger sizes >> -- and with generally heavier riders -- and that accounted for the >> difference. To me, this seems plausible. And if it's plausible that a frame >> could improve in this way, then it also seems plausible that, conversely, >> some frames could open up *too much* and become too flexy, in larger sizes, >> thus necessitating some modification to maintain the same relative >> stiffness as in the smaller sizes. >> >> Also in the back of my mind was the experience of my larger cycling >> friends who seem to break more frames than I ever have. But then, that's >> anecdotal. >> >> I don't know if Grant ran any numbers or did any testing before deciding >> to add the second tube to some bikes. Could just be for looks, or could be >> a belt and suspenders kind of thing. Or a mix. But I wouldn't say it's >> totally off base from an engineering point of view. >> >> Anyway, you've ridden more 60 (and maybe 60 plus?) size frames than I >> have, and if you say you don't feel a difference, then I can't argue. >> >> On Monday, August 3, 2020 at 8:27:15 PM UTC-7 Patrick Moore wrote: >> >>> Not true at all, unless -- perhaps -- you are well over 200 lb and carry >>> heavy loads. I owned and rode a 60 c-c frame extensively -- my best level >>> top tube size is 60 c-c -- and there was no more flex notiher 6- X 56 >>> c-cceable than with an 18" mountain bike frame. And this frame was made >>> from standard gauge, and not OS, tubes. >>> >>> I currently have another 60 X 56 c-c frame being refurbished; this is >>> also standard gauge, and it is *very* light: 5.9 lb for frame + fork + >>> steel Campy headset; I *do not* expect to need a second top tube. I'm >>> 175. >>> >>> And my best load carrier of all time, that happily and securely carried >>> 40+ in back (on an 11 oz rack!) was made from standard gauge, lightweight >>> 531 and was noticeably lighter than my 2003, 58 c-c Riv frame that weighed >>> 7 lb for frame + fork and Ultegra headset. This frame was a 58 c-c, IIRC. >>> >>> For anyone under say 250 lb who does not carry camping loads, a second >>> top tube is ornamental, not structural. Amen. >>> >>> Back when I lived in India and Pakistan and Kenya, you'd often see heavy >>> duty models of the stereotypical rod brake roadster wtih a second top tube >>> (and with heavy aftermarket fork braces), but these were bikes cheaply made >>> from cheap, weak tubing that carried 100 lb loads of firewood or 200 lb >>> loads of charcoal in gunny sacks, or a family of 4; even so, most Indian >>> and Pakistani made r b roadsters have single top tubes. >>> >>> Upshot: they look cool, but their benefit is purely aesthetic. >>> >>> On Mon, Aug 3, 2020 at 8:19 PM S <sbl...@gmail.com> wrote: >>> >>>> Yes, the extra tube strengthens the frame. Otherwise you would be left >>>> with a wobblier triangle and have to use thicker tubes and there goes at >>>> least some of your weight savings. I think it's a good solution and looks >>>> cool, so a double win. >>>> >>>> On Monday, August 3, 2020 at 11:42:08 AM UTC-7 Jason Fuller wrote: >>>> >>>>> I can imagine it's useful once you get into the 60cm range, since the >>>>> average rider weight is going up while the structural triangulation of >>>>> the >>>>> frame is going down. But I can't deny that I love the totally >>>>> unnecessary >>>>> extra tube on the Hunq so who am I to judge. >>>>> >>>>> The "unnecessary tube" I want, and would put on a Riv custom if I ever >>>>> got one, would be the lift handle from the Rosco's. I keep hoping for it >>>>> on >>>>> new models. >>>>> >>>>> On Monday, 3 August 2020 at 09:00:02 UTC-7 Patrick Moore wrote: >>>>> >>>>>> I don't want a second top tube on any bike I own because it would >>>>>> serve no real purpose and add needless weight (and also, perhaps, >>>>>> rigidity >>>>>> where I don't want it), but I do have to say that the curved second tube >>>>>> on >>>>>> those Atlantises looks wonderful *as sculpture.* In fact, merely >>>>>> aesthetically, I think that edition of the Atlantis is one of the >>>>>> prettiest >>>>>> bikes, if not the prettiest bike that Rivendell has made. >>>>>> >>>>>> In other, and very unrelated news -- but I opened the window at the >>>>>> same time as I opened the Blug window -- fenders are going >>>>>> road-mainstream: >>>>>> >>>>>> https://www.bikeradar.com/features/bikes-with-fender-mounts/ >>>>>> >>>>>> Patrick Moore, who would indeed install fenders on his Atlantis if he >>>>>> had an Atlantis. >>>>>> >>>>>> -- >>>>>> >>>>>> >>>>>> ----------------------------------------------------------------------- >>>>>> Patrick Moore >>>>>> Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum >>>>>> >>>>>> -- >>>> 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 view this discussion on the web visit >>>> https://groups.google.com/d/msgid/rbw-owners-bunch/eca5c5da-6b50-4e9d-8f49-b67f5cf68363n%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/rbw-owners-bunch/eca5c5da-6b50-4e9d-8f49-b67f5cf68363n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> >>> >>> -- >>> >>> ----------------------------------------------------------------------- >>> Patrick Moore >>> Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum >>> >>> -- >> 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-owne...@googlegroups.com <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/rbw-owners-bunch/37f7aaa9-adbd-4329-bf5c-eab5cba24d9en%40googlegroups.com >> >> <https://groups.google.com/d/msgid/rbw-owners-bunch/37f7aaa9-adbd-4329-bf5c-eab5cba24d9en%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > > > -- > > ----------------------------------------------------------------------- > Patrick Moore > Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. 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