Seat tube .

[Alf Tupper]

Hi all, help needed please, I have an old Claud Butler maybe a Cresta or a Majestic ? I'm not quite sure as I bought it second hand in the mid to late 80's, some of the decals had been removed although the rest of them remain many years later., my sun tour derailleur gave up on me few yrs ago, but apart from that, most of the original stuff is still functioning. The serial number is 0 1 4 0 8 3 I assume 83 is yr. of production ? and it's original gun metal grey paint.
My original seat post has given up the ghost and snapped is it a 26.4 straight post I need to replace the original ? so many variations.
Thanks for any replies.
On further research on this site, I now realise they only did gunmetal on a 1977/78 Cresta. but still unsure of seat post size

 

[billkilpatrick]

Get a caliper tool to gauge the diameter. If you decide to replace it with an aluminium seat post, be sure to choose one made with hardened aluminium alloy. I believe that with softer aluminium there's a risk of it sticking to the steel frame.

 

[ZG862]

When you say "snapped", I envisage a piece of seat pin still attached to a saddle and a fragment still stuck in the frame. I'd imagine that at some point you will remove the piece in the frame. There is a fairly high chance that this piece has the diameter stamped into it - although if it has snapped, this may be either because the pin was insufficiently inserted into the seat tube (in which case the markings at the base of the pin may have corroded away) or else the pin has otherwise corroded (in which case, when/if you can get the remaining piece out, the chance of reading any stamped markings may be small).
So, if you can get readings from the remaining bits of pin, Bill is absolutely right: Stick a caliper on it and measure - in more than one place as these things can become oval/otherwise distorted.

By far the worst way to establish the size is to base it on the model name, particularly if you cannot be 100% certain of the tubing type & year.

Good luck.

 

[Alf Tupper]

Thanks for the replies, yes it snapped , small section left in the saddle bracket. I was 20 miles from home when it snapped so the longest part of the tube went in a recycling bin on my way home, very difficult riding 20 miles with no saddle (ouch) so I had to jettison what I didn't need to carry. silly me, I didn't check the tube size .
Thanks any way.