long seat post for folder?

Bodger

New Member
Does anyone know where I can get a long 25mm diameter seatpost for my folder - the one that it came with is too short. I'm guessing that it's going to need to be almost 70cm.
 

palinurus

Legendary Member
Location
Watford
What sort of folder? I can't think of anything that might fit. Dahon telescopic seatposts are 27.2 mm for the telescoping bit so the other bit must be wider. How much extra height do you need?
 
OP
B

Bodger

New Member
Hi, It's a raliegh something or other - fairly new and not the rebadged dahon. The current one is arounf 6 inches too short
 

RecordAceFromNew

Swinging Member
Location
West London
In the absence of better suggestions from others, it seems to me an achievable solution is to buy a 25mm straight steel or alloy tube (something like but probably not exactly this) and a saddle clamp. These saddle clamps are usually not very fussy about tube size but yours should have a lip (i.e. not like this one) to ensure it doesn't slip down if you are using a straight tube.

The tricky bit is to size a tube that is not too heavy yet stout/safe enough to withstand the huge bending moment such a long post will experience at the clamp on the frame. Obviously the rider's weight is an important determinant. For your reference a quick sample from my bike bits bin finds the wall thickness of an alloy post I have to be 3mm, while a steel one is 1.5mm. But they are your typical 350mm length posts. Without doing the maths (but since doubling the length doubles the bending moment) I would have thought as a starting point the wall thickness of your post would need to double these.
 
OP
B

Bodger

New Member
thanks I'll have a look out for tubing should I not be able to find a real seat post.
 

tyred

Legendary Member
Location
Ireland
Take two standard traditional chromed steel seat posts (the type which taper in to fit the saddle clamp. You will find that the tapered end fits into the end of the other post. Get it brazed together and you have one long seat post. It's what I did on my shopping bike which is really a bit too small for me.
 
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