Here are some geometry comparisons of small touring bikes (Riv Atlantis, Surly LHT, Soma Saga). ETT = Effective Top Tube, SO = standover in mm, STA = seat tube angle.
Make-and-size ETT SO STA Atlantis-47cm 520 712 72.5 LHT-46cm 515 724 74.5 LHT-42cm 505 703 75 Saga-47cm 517 714 74.5 Saga-44cm 502 701 75 In this chart, note the difference in the seat tube angle (STA) on the Atlantis. To get the same saddle position relative to the pedals, you'd have to push the saddle back on the Surly and Soma bikes. Every degree of STA is worth a little over 10 mm of saddle position in a bike of this size (use your high school trig -- exact calculation depends on seat height). The correction is about 20 mm for a 74.5 degree STA and 25 mm for a 75 degree STA. So the equivalent ETT for the 46 cm LHT would be about 535 mm, and for the 42 cm LHT it would be 530. For the Soma Saga 47 cm the equivalent ETT would be 537, and for the 44 cm Saga it would be 527. Bottom line: the Atlantis' stated ETT measurement is the longest of the bunch, but because of the shallower seat tube angle, it has the shortest reach. Handlebar height and head tube angle also affect reach. This issue is addressed in more generality and detail here: http://www.rivbike.com/article/bicycle_making/the_top_tube_ruse Lisa PS: If the OP's friend's PBH is 670 mm, she won't be able to stand over any of these bikes. She may need a mixte, or a bike with 24" wheels. On Jul 27, 1:35 am, Ian Dickson <iandicks...@gmail.com> wrote: > > The bike is tiny, but with the small wheels and level top tube it > looks normal and nicely proportioned. A lot of small frames look like > they've been squashed. I haven't looked at the geometry, but I would > guess that the 46cm LHT is similar to a 47cm Atlantis, which would be > nicer if your friend is willing to spend the money. My wife is very > happy with the Surly, though. They are nice bikes. > > Ian > > On Jul 26, 8:43 pm, Ken Mattina <ken.matt...@gmail.com> wrote: > > > The soma buena vista comes in a 42cm size. The salsa vaya comes in a 50cm > > although according to the geometry chart, the seat tube measures 45cm. -- 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-bu...@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.
