seatpost diameters

keanu122 said:

I know that you can't fit a 27.2 mm seatpost in a frame that is only 27.0 mm (I've tried). But my question is, do you think it would be okay to put a 27.0 mm seatpost in a frame that is designed for 27.2 mm seatposts? Thanks.

I think you can get spacers that "pad out" the difference. Not sure about this though.

I have two bikes, one of which has a 27.2 seat post and one which has 27.0.

You are quite right that the 27.2 will not go into the 27.0 frame (not very far anyway- I have tried too)!

The 27.0 post does (obviously) go in to the 27.2 frame but it does have a very slight wobble side to side unless the post is shoved quite a way in. I didn't try tightening the post/ riding but I imagine even such a slight size difference would result in noticeable slippage of the post and possible damage to post or frame.

Also, I doubt that a shim for such a small difference would be available. It would have to be 0.1mm in thickness which is probably slightly thinner than tin foil!

In short, I wouldn't risk doing it if I were you. Far easier to buy a 27.2 post to fit a 27.2 frame. (a 27.0 post for a 27.0 frame however is a bit more difficult to find these days).

darrenf said:

You are quite right that the 27.2 will not go into the 27.0 frame (not very far anyway- I have tried too)!

I've heard of them going in, but never coming out. 😉 You can get shim stock in 0.1mm thickness and a variety of materials here: www.mcmaster.com If this is a steel frame you don't even need to shim it. Just crank down on the clamp, and it should be ok.

darrenf said:

Also, I doubt that a shim for such a small difference would be available. It would have to be 0.1mm in thickness which is probably slightly thinner than tin foil!

In short, I wouldn't risk doing it if I were you. Far easier to buy a 27.2 post to fit a 27.2 frame. (a 27.0 post for a 27.0 frame however is a bit more difficult to find these days).

I'ts called a beer can shim and it will work.

I stand corrected