Seat post size help

[nathanicola]

I am using an old Raleigh flyer frame with the gear change on the down tube to build a retro racer. Looking to replace the seat tube for an alloy one as the chrome is starting to rust but the closest measurment i can get from measuring the top of the frame with a tape measure is 26mm but its not very accurate and i dont have a micro meter (or whatever there called). The new stems seem to be 25.4, 26.4, 26.8 27.0, 27.2. Can anyone tell me is there a standard size that the old raleigh's used.

 

[Drago]

25.4 was a common old Raleigh size, but any decent LBS will latch the size if you take it in.

 

[smokeysmoo]

Or whip it out, (only the seatpost ), and the size is often stamped on it.

Not always TBH but worth a try.

 

[tyred]

It is probably either 25.4 or 26.4 but if in any doubt, take either the frame or the old seatpost to a decent bike shop.

Whatever you do, do not try to fit one that seems a little tight with a hammer...

 

[grumpyoldgit]

Cut a strip of paper about 1 inch wide by 5 inches long,wrap this around your seat post,mark a line where the full circumference would end.Now lay this out flat,measure the length with a ruler,in mm,divide this by 3.142 & you will have the size.
All this is easier than it sounds.

 

[KateK]

I've just had to replace an alloy seat post replacement for my old raleigh as the first one I bought was duff as it was actually smaller than it was marked and kept slipping. I ended up shearing a bolt trying to get it tight enough. The new replacement doesn't slip at all.

 

[nathanicola]

Cut a strip of paper about 1 inch wide by 5 inches long,wrap this around your seat post,mark a line where the full circumference would end.Now lay this out flat,measure the length with a ruler,in mm,divide this by 3.142 & you will have the size.
All this is easier than it sounds.

Of course why didn't i think of that lol. I'll try this later, thanks for replies chaps.

 

[sidevalve]

Just for interests sake you can buy a basic vernier caliper guage for less than a fiver [and an electronic one for about £12] and it will be usefull for other jobs besides,[ measuring chain wear etc].
PS unless you're into engineering a micrometer is, although very accurate, maybe not for the job.

 

[KateK]

Just for interests sake you can buy a basic vernier caliper guage for less than a fiver [and an electronic one for about £12] and it will be usefull for other jobs besides,[ measuring chain wear etc].
PS unless you're into engineering a micrometer is, although very accurate, maybe not for the job.

Less than a fiver? very tempting. i always end up using one of those screwup spanner thingys (sorry vocabulary malfunction) and measuring the distance.