25.4 vs 25 mm seat post
 

I have an old Vitus with a short seat post. diameter is stamped 25mm. how much trouble do you suppose a 25.4mm post will give me? i have not been able to find 25mm.

It will give you plenty of trouble. I found a 25.0 from Performance on the first Google hit: https://www.performancebike.com/sunl...iABEgJPRfD_BwE

25.4 vs 25 mm seat post

.6 mm.

How much trouble will that give you? Do you have a very big hammer? Even with the very big hammer, it isn't going to work. I found a 25mm seat post in about four seconds by searching on amazon. Thompson makes one too.

There was a guy on this thread looking to trade some 25.0 post a long time ago. You could post you are looking for one and see what comes up.
https://www.bikeforums.net/classic-v...l#post22580135

so weird i was not able to find any. now seems they are coming out of my ears.

thanks all!

Great!

It will give you no trouble at all because there is no way, shape, or form for you to get that seat post into the frame.

i do appreciate your response, really i do. but wouldn't not being able to get the post into the frame be the definition of trouble?

i have a 25mm seat post just a day or two away now.

The implication is that you won’t unintentionally damage the frame, have a seatpost that forever slips, etc. so long as a hammer is not involved.

If this is a Vitus with a set screw to hold the seat post, know that removing the seat post can be a bit tricky if the screw gouges the post. I’ve seen others file a small flat so that any raised burrs don’t interfere with the frame on removal, though I’ve never needed to do that myself.

I own a Vitus 979; one of my favorite bikes, despite having a fleet of carbon things. It takes a 25.0 post. Attempting to install a 25.4 or larger may be possible if you have a pneumatic press capable of generating several tons of compressive force. Bike and post would be destroyed in the process. When it comes to seatposts, 0.2mm is the difference between the post sliding down with gravity, and being locked up tight.

Wait for the proper post to come, and be careful with installation. Your bike frame is irreplaceable. If you have the older 'ears' type seatpost lug, do not overcook the tension and crack the lug. If you have the newer grub screw, make sure the grub screw is greased and tight! Do NOT strip the grub screw!