very thin seat post shims ?

[hoogerbooger]

Am building up a an 1977 mixte frame with mainly contemporaneous (ish) parts.

I have a 1980 ish SR laprade seat pin at 26.4mm that is too small . Have just tried a horrible modern 27mm seat pin and it's too big.....so the mummy bear I need must be a 26.8mm .

I will probably look out for a second hand one of suitable vintage and looks....but is there a safe way to use a shim with such a small gap to fill ? ( the SR laprade served me well in it's previous life, so it would be nice to use it)

googling I see some have used bits of coke can ? Ignoring the sharp edge issues ...could it mechanially work ok as a temporary or long term option. Any advice ?

( seat tube doesn't have a perpendicular cut top, so I'll have some fun trying to work out how to make it not show too much and not drop down the seat tube)

[Brucey]

could be 26.6mm you need. Coke can works OK but getting the right amount in there is not always easy.

It might be better to run a reamer in the frame first, and then to get a seat pin that fits, or to have someone with a lathe make the 27mm one the right size to fit the frame or something.

cheers

[hoogerbooger]

argh! I can't measure that close.

Any idea if 26.6mm would have been common on a 1977 531 butted seat tube ?

[De Sisti]

As a last resort a jubilee clip may help.

[Brucey]

argh! I can't measure that close.

Any idea if 26.6mm would have been common on a 1977 531 butted seat tube ?

yes, esp if it is a french frame

cheers

[scottg]

A Reynolds No.4 seat pin is 26.9mm
26.8mm is out there too.

Reaming is good, measuring the actual size of the seat pin is worthwhile.
Nitto is usually spot on, some others not so much.