Seatpost slipping down no matter what

[bikeworkshop]

Have it welded in place

Glue is cheaper.

 

[PanoIgano]

Are you 100% sure the seat post is the correct size?
It looks to be a Fat Chance yo eddy?
These use a specific size post, quite hard to find, 29.4 from memory.

It's a FAT TUBE seat post and the one that came with the bike when it was sold in 1991. In fact, it's a very interesting seat post in that its interior is not hollow but has a cross that goes throughout its length to reinforce it. I am not describing it too well. Will take a picture and you will get the idea.

Anyhow, the issue now that I removed the QR and replaced it with an allen screw seems to have been gone! Will see how it goes in bigger rides.

 

[1552]

Ah ok, well there is a good chance if it's the original quick release after all these years the cam action (egg shape) on the qr has worn so essentially it's just closing, not actually applying extra pressure as you push it closed, if that makes sense

 

[Elev12k]

I have 3 bikes with 29,4mm post: Yo, Verlicchi DH and Batavus. Today took delivery of two Kalloy SP 248 in silver and black for the Batavus. I do like the SP 248. It is period correct, 400mm long, but probably not fancy enough for a Yo.

 

[Black_puma]

With my three oldest GT's I found that the seatpost that came with the bikes were too small.

1992 GT Bravado now has 27.2mm seatpost, though initially had bought a 27.0 seatpost but was slipping and is now fitted to my 1992 Pantera.

My 1991 GT Avalanche came with a 26.8 Deore DX seatpost fitted (now sold to a fellow Retrobiker), but also came with the original seatpost in the sale which turned out to be the correct size! No more slipping.
Considering I ride my bikes daily I have to make sure to have the correct fit as not to damage my frames with ill fitting seatposts.

 

[bikeworkshop]

There's a time between "shiny and new" and "cool and collected" where things are undervalued - owners fit parts that aren't right and don't maintain adequately.
It was worse in the late 90s when frames took posts in multiple close sizes:
26, 26.2, 26.4, 26.6, 26.8, 27, 27.2
And plenty of others!
Modern bikes tend to be
27.2, 30.9, 31.8
These posts can't really be interchanged.