Overwhelmingly 27.2mm for upper-tier Italian steel. Sometimes 27.0 for a tall frame size, and maybe some other exceptions. Take a bunch of measurements at different points around the opening; your 26.5 at the one point might be an outlier. But a caliper is not as good as the seatpost sizer rod that shops often have.
conanlikes on
We never sold these lower end basso frames but the Bianchi frames at this end of the market had a range of sizes 26.4, 26.8. Depends on the country of origin. I swear we sold a thousand Basso Gap frames but they were all 27.2. I can’t remember the importer maybe ten speed drive? Their catalog might say?
psyentologists on
Take it to your LBS and they’ll have a sizing rod that they’ll use to get you the exact measurement.
Typical-Violinist-49 on
I put a black carbon fiber seat post on my vintage bike. You can’t tell. I did it to avoid rusting and seizing.
micbanand on
the old europeans where not standart. but normal went from 26mm by 0,2mm increase.
so if yours is loose and round 26,5mm you want a 26,4mm seatpost 🙂
According-Regret-311 on
It isn’t possible to measure tube ID accurately with calipers. You need to try actual seat posts or use a cylindrical tube sizing gauge. 26.8, 27.0 and 27.2 are all real sizes.
7 Comments
26.8mm?
Overwhelmingly 27.2mm for upper-tier Italian steel. Sometimes 27.0 for a tall frame size, and maybe some other exceptions. Take a bunch of measurements at different points around the opening; your 26.5 at the one point might be an outlier. But a caliper is not as good as the seatpost sizer rod that shops often have.
We never sold these lower end basso frames but the Bianchi frames at this end of the market had a range of sizes 26.4, 26.8. Depends on the country of origin. I swear we sold a thousand Basso Gap frames but they were all 27.2. I can’t remember the importer maybe ten speed drive? Their catalog might say?
Take it to your LBS and they’ll have a sizing rod that they’ll use to get you the exact measurement.
I put a black carbon fiber seat post on my vintage bike. You can’t tell. I did it to avoid rusting and seizing.
the old europeans where not standart. but normal went from 26mm by 0,2mm increase.
so if yours is loose and round 26,5mm you want a 26,4mm seatpost 🙂
It isn’t possible to measure tube ID accurately with calipers. You need to try actual seat posts or use a cylindrical tube sizing gauge. 26.8, 27.0 and 27.2 are all real sizes.