SheldonBrown.com has an entire page devoted to seatpost sizes: https://www.sheldonbrown.com/seatpost-sizes.html
If you have an older bike, things get interesting. I have a ‘72 Cinelli (26.2mm) and a ‘71 Motobecane (26.4mm) that both require seatposts that can be somewhat difficult to find. --Eric N > On Nov 11, 2019, at 11:31 AM, Laing Conley <lcon...@brph.com> wrote: > > Seat post size is the inner diameter of top of the seat tube (usually single > butted - thin part at the top) - change the tube = change the seat post. When > the Sam got 0.2 thicker tubes (same outer diameter = same lugs), the seat > post got smaller -> 27.2 minus 2 x 0.2 = 26.8. > > > Laing Conley > > > -----Original Message----- > From: rbw-owners-bunch@googlegroups.com <rbw-owners-bunch@googlegroups.com> > On Behalf Of Joe Bernard > Sent: Monday, November 11, 2019 1:53 PM > To: RBW Owners Bunch <rbw-owners-bunch@googlegroups.com> > Subject: [RBW] Anyone elsed notice Rivendell's freaky, inconsistent seatpost > standards? > > I believe it's a matter of what seatlug is used for a particular model. 27.2 > was on the MUSA frames, 29.8 was the socket-style lug originally used on all > Clems and now only the big ones, 26.8 is the lug currently used on the > smaller Clems and all MIT fully-lugged bikes. > > -- > 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 view this discussion on the web visit > https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_msgid_rbw-2Downers-2Dbunch_ab572e71-2D3b22-2D4f3f-2Dae42-2De0bfbe0955b1-2540googlegroups.com&d=DwIFaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=fbpz-LhLhQnqxV9ePfEuoQ&m=zdOnZkL4-imZ2uJ9jNdVckdW6eHIum54VBbtRYEfZX4&s=IC6ULtQUHCeB8oelCIAYrk-8wx3ClbewZBhUNk-l_gQ&e=. > > -- > 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 view this discussion on the web visit > https://groups.google.com/d/msgid/rbw-owners-bunch/BN8PR14MB2883A8FFFDCFA7AF8A6D0680C3740%40BN8PR14MB2883.namprd14.prod.outlook.com. -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/7BF2B74C-606B-4747-9A91-3B20326C69B5%40me.com.
