Seems like the wall thickness that naturally corresponds to a 26.8 seat post would be 0.8 mm. So, if the 26.8 is not the result of sleaving or excessive reaming of a smaller diameter, then the frame is built with a straight guage 0.8 seat tube, like Columbus Gara (not sure what earlier versions might have been called) or perhaps with a double butted seat tube that was 0.8 at the top (I think this was done in some japanese tubing bikes in the 80's).
Or maybe there was a single butted seat tube around that was 0.8 or smaller at the top. I'm far from expert, but the heaviest I've heard about was 0.7/1.0, Columbus SP (and later, Thron). My 80's Team Miyata took a 26.8 seat post and proudly boasted of proprietary triple butted tubing, although I don't know details of the seat tube butting.
Kerrigan Bennett Pleasant Hill, CA
Archive-URL: http://search.bikelist.org/
At 03:23 PM 8/17/06 GMT, brianbaylis(AT)juno.com wrote:
>The reason some Italian bikes of old used 26.8 seat posts is because
>many of the seat tubes are sleeved.
Brian,
My Sutherland's 3rd Edition shows Italian frames with butted tubing as having seatpost diameters of 26.8, 27.0 and 27.2 mm. I wonder where that comes from. Would there have been other brands of butted tubes used with that i.d., or the sleeve you're talking about, or is it just wrong?
John Betmanis <johnb(AT)oxford.net>
Woodstock, ON Canada