Thanks for the feedback on the frame sizing thread. Wasn't sure to start a new thread or continue with the question there but figured this may lead to a whole new kettle of fish. Taking the advice of the thread I see that I will need to raise the seatpost past the maximum so wanted to change it around with another seatpost I had that was pretty similar, at least in age of bike. I then saw that it was too wide. There seems to be a standard today of seatpost diameter, was this not the case in days of old? Where would be the best place to find a seatpost that has the correct diameter? EBay?

ebay is your friend. what diameter do you need?

tarmenel, The seatpost usually has it's diameter marked near the bottom of the post. Depending on wear it may be hard to see.

Brad

Unfortunately Bradtx there is no marking except for the maximum extension that the seatpost can be extended. The bike is a Raleigh Winner and it seems that the seatpost itself is elliptical. Taking the measurements I came up with two figures, 25.2mm front to back and then 25.8mm left to right. Seems a bit weird and this is why I thought initially the seatpost from the LeJeune would fit as it is 25.6mm. Don't really know what to do?

While there are some aero posts, the degree of ellipticity you're measuring is more likely due to a post that has been distorted or an error inmeasurement. Errors in measurement can occur due to dirt in the caliper jaws, the caliper not being perpendiular to the post, foreign material on the post or a marred post. To avoid potential errors, it is best to measure well above the insertion point, where it is least likely to be marred or distorted. Also, clean the post and caliper jaws.

Based on the measurements it is probably a 25.4mm post. This is a very common size on entry level bicycles. You don't say what length the current post is, but posts up to 400mm long are readily available and quite inexpensive.

Range of seat post diameters depends on the OD of the seat tube , the wall thickness of the Tube ,
and whether the finished frames seat tube was reamed out when finished ,
a hand reamer is an adjustable cutting tool with straight sides..

so I for example , have enlarged my frame's ID to suit, have an RB1.. they ship as a 27.0,
so the fitting of a 27.2mm post required shaving out 0.2 mm from the upper portion of the seat tube..

Many light steel frames have a 27.2 ID when finished. abundant product choices in that size.

had a standard Diameter tube Aluminum AlAn, it used a 25.0 seat post..

some companys, like USE make just a few sizes of seat post, then Shims fill in the sizes in between.

a perfectly valid method .