seat post size?

[jim55]

any tips on finding out my seatpost internal dia(i dont have a set of calipers to measure) ?fyi its an old style531 frame with a 1" steerer and the seat post i have is too loose ,i know u can buy a shim but i dont know what size i need

 

[tyred]

Depends on what flavour of 531 but probably 27.2 or 26.8. Or maybe 27!

A coke tin makes a perfectly acceptable shim.

If you really want to do it properly, take the frame to a bike shop and ask them to measure it and supply a post to fit.

 

[HLaB]

If you are lucky remove the original seat post and it may be written on the post, given its too loose that'd only be a place to start. Btw with on post I had a regular shim would have been too much and I just had a coke can shim.

 

[biggs682]

27.2 is norm for 531 frames