Doug- The difference in radius between 700c and 650b wheels is 19 mm. (622 - 584)/2
So, any rim-brake bike can convert from 700c to 650b -- *if you can find brakes with 19 mm more reach*. The Sam H is already using "long-reach" Tektro R539 (55-73 mm) calipers, so you would need "very-long-reach" caliper brakes, which don't really exist. Weinmann/DiaCompe 750 centerpulls get to 75 mm reach, even the execrable Dia Compe 810 single pivots only reach to 79 mm. Also, changing wheel diameter can change geometry; it can lower the frame. If you fit a 19 mm wider (aka taller) 650 tire than the designed 700c tire, then you'd break even. But chain stays and fork legs are rarely wide enough to allow such a wide tire. So, you end up with a tire that is somewhere between 0 and 19 mm wider, and a commensurate compromise in geometry. Of course, you could have the frame modified with cantilever posts or disc brakes. That would solve the brake issue, but the geometry issue remains. I'm a 650-conversion skeptic because of experience; my Riv Road Standard went from 700x25 to 650x38. But the frame is noticeably lower; I'm very careful not to scrape pedals in turns. Just saying that it's a complex change that should be researched before pursuing. One of Grant's signatures is designing frames around proportional wheel sizes. Some of Rivendell's models come with 26" wheels (in small frames), 650b wheels (in med frames), and 700c wheels (in large frames). He puts a lot of thought into the right wheel/tire and right geometry for the intended use. If you choose to change that on your bike, don't do it cavalierly. On Wed, May 2, 2018 at 2:01 PM, Doug Bloch <dougbl...@gmail.com> wrote: > Nice bike. Not to hijack your FS thread, but can the Sam take 650bs? > > Doug > Alameda CA USA > > -- > 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 https://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 https://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
