Bike Forums - View Single Post - Estimating seatpost diameter

02-12-20, 08:15 AM

#7

Unca_Sam

The dropped

Join Date: Oct 2018

Location: Columbus, OH

Posts: 2,144

Bikes: Pake C'Mute Touring/Commuter Build, 1989 Kona Cinder Cone, 1995 Trek 5200, 1973 Raleigh Super Course FG, 1960/61 Montgomery Ward Hawthorne "thrift" 3 speed, by Hercules (sold) : 1966 Schwinn Deluxe Racer (sold)

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Quote:

Originally Posted by Wilfred Laurier

https://www.sheldonbrown.com/seatpost-sizes.html
Sheldon Brown's seatpost diameter database lists the 1995 Cinder Cone (the earliest one listed) as having a 26.6mm post. And a number of other pre-mid-'90s Kona bikes as 26.6.

I've seen that. He also stated that the measurements are volunteered and should not be blindly trusted because he can't verify them. There's an old thread about an early Trek MTB, and truing to use the tube specifications to figure the seatpost diameter. The consensus there was that (mostly brazed) bikes can have a .2mm tolerance for distortion. My frame is welded, but I don't know if that's better or worse for tolerances. .2mm is on the edge of what's considered an acceptable variance for a bicycle, isn't it?

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