Originally Posted by dck

I put a 25.4 mm seatpost in the UO8 after removing the sleeve.

Regarding all the discussion above about the wisdom of replacing the cottered crank, I'll offer my 2 cents.

If you like the cottered crank, by all means leave it on. I only replaced mine because someone gave me an Ultegra crank and I thought it would be fun to try to put it on the Pug. Once I did that I kinda got carried away and replaced everything else except the FD, the chain and the headset. It's kinda ironic however since I bought the bike new in 1972 and it's got a lot of sentimental value. Nontheless, it rode very well after all the upgrades, and weighed a heck of a lot less. I've since torn it back down to the frame and I'm putting all the parts on the UO18.