Post slipping in 1992 Merlin despite being correct size

[Minifreak]

Hey guys, got a slight issue. I have a 1992 Merlin Titanium which I believe should take a 27.2mm seatpost. The frame is in good order and the clamp bolt does up tight with a small gap. The post is an NOS Syncros. I am using a normal amount of grease between the parts but a during riding it slips a small amount, 1.5cm over a 5 hour ride.

Anything I can do? Would you recommend trying a 27.4mm post, any idea if it would even fit?

Thanks for your help in advance, Tim

 

[Minifreak]

Anyone?

 

[Splatter Paint]

Re:

I had a frame do this before, the very top part of the seat tube had worn oval though repeated movement. I cured it by making a very small, maybe 1cm x 2cm shim made from an old foil food tray (fractionally thicker than baking foil). As I slid the post in I got to about 2cm above the insertion length I wanted and folded the foil around the front of the seat post and held in place with a little dab of grease. Then I gently applied pressure to post, pushing it backwards whilst at the same time holding the shim and pushing it into the seat tube. It actually wedged the post tightly after a few goes at trimming the shim smaller and smaller so that nothing protruded. The seat clamp went on and no more slippage. I know the post was the right size, because I tried a 0.2mm bigger one and it only went in ~3 cm.

The only trouble with this method is that raising and lowering the post is a pain as you have to re-fit the shim each time, hey ho.

SP

 

[Minifreak]

Re:

That's great, I'll give it a go. Thank you for that

 

[walleater]

Carbon friction paste is good in this scenario.

 

[Antstark]

Re:

That's really odd.....because most of the threads on here about Merlins and seatposts say 27.2 never seem to fit....to big not too small

 

[Harryburgundy]

Carbon friction paste is good in this scenario.

Agree...and you won't need much of it

 

[Minifreak]

Right I'll try the carbon friction paste prior to shim idea.

Antstark, my 1990 Merlin came with a 27.2mm seatpost from new. Which that wasn't the size though. Pain to find nice condition periods Syncros post in!

 

[raidan73]

Re:

Might sound stupid Tim but have you checked that your 27.2mm post is actually 27.2mm?

 

[Minifreak]

Not with callipers. Shall do.