Bill: Not that I'm likely to try this notion, but it would seem as long as you used a 650b tire that yielded the same OD as the 700c it replaced, the BB would not drop. 622 - 584 = 38 mm. Granted, that's a substantial increase in tire size, and most Atlantans are probable running something in the 35-45 mm width range already. Assuming a 40 mm tire on a 622 mm rim, the OD will be around 700 mm. So a comparable 650b would be around 60 mm. All of this is theoretical & ignores that tires are often not true to size.
Is my logic right on this? Or did I miss something important? dougP On Monday, November 27, 2017 at 12:31:52 PM UTC-8, Bill Lindsay wrote: > > William! asked "Can anyone comment on what geometry changes Rivendell made > to accommodate the smaller wheel size?" > > Obviously you are already looking at the Geometry Chart, right? > https://www.rivbike.com/pages/geometry > > The biggest difference to accommodate smaller diameter TIRES is BB drop. > The 650B Atlantis has 67mm of BB drop. The 700C Atlantis has 80mm of > drop. The 26" Atlantis has 48mm of drop. A 700C Atlantis has more BB drop > than any frameset I know of. Running smaller wheels on a bike with more > drop than 99.5% of bikes out there is a great recipe for pedal strikes. If > you don't worry about pedal strikes, go for it. > > Bill Lindsay > El Cerrito, CA > > On Monday, November 27, 2017 at 9:42:04 AM UTC-8, William! wrote: >> >> Somewhat off topic, but has anyone here converted an Atlantis to 650b? >> I've got a larger (61cm) Atlantis and I've been thinking of building a >> second set of wheels – mainly so that I can run knobby tires without >> hitting fender clearance issues. Can anyone comment on what geometry >> changes Rivendell made to accommodate the smaller wheel size? >> >> William >> >> On Monday, November 27, 2017 at 9:01:58 AM UTC-8, Max S wrote: >>> >>> So, anyone ride a 650b Atlantis yet?.. ride reports? >>> >>> I was tempted by the 58 cm b-nut Appaloosa for sale, but not digging the >>> double top tube aesthetic, and not completely sold on the super-long chain >>> stays. Now that I’m laid up with a freshly broken collarbone now and the >>> perennial “simplification” urge struck - sell a couple of bikes to replace >>> with a single 59 cm 650b Atlantis, run 2 wheelsets (42, 48/52/60mm if it >>> fits)?.. >>> >>> - Max >> >> -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
