Oh, I forgot to point out that for top tubes of the lengths in question here (60ish cm), every degree increase in TT slope raises the top of the head tube by about 1 cm. (Math solution is below.) This means that the 64 cm Atlantis and the 65 cm AHH put the handlebar at just about equal heights. By that logic, I guess the 60 cm Hillborne trails the other two in handlebar height by about 0.5 cm. (I'll have to get a stem riser.)
Math solution: Arc length = radius*angle where angle must be in radians. Arc length = extra head tube height obtained Radius = top tube length Angle = (# of degrees)*(3.14) divided by 180 Head tube height increase = (60 cm)(1)(3.14)/180 = approximately 1 cm Anybody want to do the prediction of how TT slope increases the effective TT length? On Jul 9, 2011, at 9:57 AM, James Warren wrote: > > > My Atlantis is 64 cm and has a 2.5 degree TT slope. > > My Hillborne is 60 cm and has a 6 degree TT slope. > > My AHH is 65 cm and has a 1.5 degree TT slope. > > The expanded frame geometry (with its 6 degree TT slope) was meant to allow > fewer sizes to fit more people. A 60 cm Hillborne fits me well, while that > size in AHH or Atlantis would be too small. (Most other companies, when > showing a bike with the 60 cm Hillborne's dimensions on the geometry page, > would actually name it a much larger size. Most of the companies that sell > sloping TT frames list a size name that is much longer than the actual seat > tube length. In my opinion, Rivendell's way of naming the frame size is far > more informative and clear.) > > This means that my Hillborne, has a headtube that is about as long as the > headtubes of the AHH and Atlantis in my sizes. So I would conclude from this > that for equivalent uses, these three models all would equally need or not > need a second top tube. > > Am I missing anything? > > Note: the reality of my uses of the frames don't match the above theoretical > considerations. My Hillborne is set up quite differently from my AHH. > > -Jim W. > > > On Jul 9, 2011, at 9:18 AM, Aaron Thomas wrote: > >> If the structural integrity issues produced by the 6 degree upsloping TT are >> such that Grant has to make a hard sell on 2TT or compromise on strength, >> why not go back to nearly horizontal top tubes? My Romulus and Bleriot both >> seem plenty stiff with their lesser 1-2 degree upsloping TTs. When the >> 6-degree upslope on the Sam was announced, it seemed to me to be something >> of solution in search of a problem. And I was never all that crazy about the >> aesthetics of the 6-degree upslope. Although it's grown on me somewhat, I >> still prefer the look of a horizontal (or nearly-so) TT. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "RBW Owners Bunch" group. >> To view this discussion on the web visit >> https://groups.google.com/d/msg/rbw-owners-bunch/-/MTL5kKe7pHoJ. >> To post to this group, send email to rbw-owners-bunch@googlegroups.com. >> To unsubscribe from this group, send email to >> rbw-owners-bunch+unsubscr...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/rbw-owners-bunch?hl=en. > > > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > To unsubscribe from this group, send email to > rbw-owners-bunch+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
