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PostPosted: Fri May 23, 2008 10:04 am 
MacRetro rider
MacRetro rider

Joined: Fri Feb 09, 2007 4:16 pm
Posts: 8658
What diameter is the seatpost for a Peugeot phantom as its smaller in diameter than the usual default 25.4mm.

I have a fly tipped Peugeot frame that i plan to turn into a 'Pub' Bike made of internally lugged Carbolite 103 steel which I know is cheapo high ten but is very neatly joined with the internal lugs. I thought the smallest diameter seatpost was 25.4mm but now it appears I am very much mistaken. I feel a bodged seatpost coming on as I doubt the size it requires exists anymore.

Cheers


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PostPosted: Mon May 26, 2008 3:58 pm 
Devout Dirtbag

Joined: Mon Mar 03, 2008 11:02 pm
Posts: 117
Location: Manchester
23.6 IIRC.

Get a cheap 25.00 Kalloy or summat & have a machine shop turn it down. Check it for cracks, EVERY TIME you ride it.

J


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PostPosted: Mon May 26, 2008 6:25 pm 
King of the Skip Monkeys
King of the Skip Monkeys
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Joined: Wed Nov 07, 2007 4:34 pm
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Location: Moomin Valley
http://cgi.ebay.co.uk/OLD-SCHOOL-24-mm- ... dZViewItem


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PostPosted: Mon May 26, 2008 9:43 pm 
King of the Skip Monkeys
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more appropriate:

http://cgi.ebay.co.uk/BANKRUPT-BIKE-BMX ... 18Q2el1247

I knew there was some very small BMX stuff but couldnt remember specifics....


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PostPosted: Tue May 27, 2008 10:53 am 
Old School Grand Master
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Location: Lost in Translation
legrandefromage wrote:
I knew there was some very small BMX stuff but couldnt remember specifics....

Tangential anecdote. I was shopping at the Bastille market one Sunday morning and I saw a weird little folding bike with a strange seatpost - really skinny at one end with a fat bulge in the middle, then tapering to really skinny again. I stared at it for a while, completely stumped. The bulge would stop the post sliding right down into the frame, but I couldn't figure out why you'd want that, especially on a folding bike.

Then it struck me. The original post must have been stolen or damaged, and someone had stuck an oversized (22.2mm - 31.8mm - 22.2mm) handlebar into the frame as a seatpost.

I guess you had to be there.


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PostPosted: Tue May 27, 2008 11:03 am 
King of the Skip Monkeys
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Location: Moomin Valley
well, theres your answer, if a 22.2 stem can be tightened up in the seatpost hole of your frame without movement, a set of handlebars will do the trick.

:shock: :lol:


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PostPosted: Tue May 27, 2008 2:08 pm 
MacRetro rider
MacRetro rider

Joined: Fri Feb 09, 2007 4:16 pm
Posts: 8658
Alternative way of sorting problem, fit a shim.

BMX seatpost is 22.2mm, actual seatpost required is 23.6mm so subtract smaller from larger you get 1.4mm.

Next divide 1.4 by 2 so that you get the thickness required of shim on either side of any point posts circumference which is........0.7mm !

Get hold of a shim of 0.7 wall thickness such as a USE 25mm - whatever size shim in this case 26.4mm.

Cut a wider gap than the one the shim will come with to prevent the shim overlapping itself when wrapped around the smaller diameter 22.2 mm BMX seatpost.

Fit to bike and tighten up clamp, post should hopefully not slip.

This idea should work although wrapping aluminium sheet from an old drinks can several times around the post might also work and be cheaper.

Thanks though for the seatpost diameter in the first place Team Lard, these individual manufacturers who think their ways better than the accepted norm do not half make us retrobikers life hard !

Cheers


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PostPosted: Wed May 28, 2008 11:05 am 
King of the Skip Monkeys
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Location: Moomin Valley
or just tighten seat clamp till seatpost dont move no more...?


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PostPosted: Wed May 28, 2008 12:06 pm 
MacRetro rider
MacRetro rider

Joined: Fri Feb 09, 2007 4:16 pm
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LeGrandeFromage,

Not keen to tighten a clamp that much, manufacturers specify a seat post diameter for a reason !

Probably going to pass frame onto local recycling charity now anyway.

Cheers for all help given,

Velomaniac :)


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