A sad little 46cm Raleigh Rapide road bike was dumped on my doorstep a few months ago, and I just got around to rehabbing it. The problem is that the seat post in it is a 25.4, and the seat post it needs is a 25.8. The 25.4 will not fit snug enough to tighten up without doing damage to the seat tube. I have a pile of seat posts in the bin, but no 25.8's - a bunch of 25.4's, a 26.0 and a bunch that are bigger than that.

Can this be shimmed safely? Failing that, does anyone have a 25.8 post they can send/sell/trade me?

It can be shimmed. I'll check the parts bin today and see what I have.

WHAT! NO PICTURES!!!!

Let me check my collection of spares. It seems to me I've run into the same challenge, only in reverse, and I need a 25.4 and have a 25.8.

+1. It can be shimmed. But why not just get a 25.8mm from the LBS? They are still readily avialable and probably cheaper than shipping from a forum member. Or is this another Canada only deal, like those 11-28T freewheels? My supplier lists 25.8mm posts in steel for $4.00, aluminum for $5.50 and micro-adjust for as little as $8.50.

Duh - the obvious solution, right in front of me. Sometimes ya just don't see the forest for the trees.

Bob - if you need a 25.4 and have a 25.8 maybe we can trade. If not, the LBS opens tomorrow and I'll probably take T-Mars advice.

Well, I thought it was a 25.8 (the "5" has a scratch running through it). I put the calipers on it and I believe it is a 26.8 (I need digital calipers, Santa).