Seat post diameter for Reynolds 531 ST frame?

I've finally got my 1985 Raleigh Classic 15 stripped down and ready to take for painting, which means I'm starting to think about what new parts to buy for it to build it back up with.

I'm definitely going to need a new seatpost, the old one had been bodged in there with sellotape.

Does anyone know whether I'll need one with a diameter of 27.0mm or 27.2? I know normal 531 tubing is usually 27.2 but I'd read that touring frames (mine is 531 ST) after often 27.0.

I'm afraid I don't have the tools to be able to check easily at the moment. I guess if anyone has a Raleigh Randonneur or Royal from the same era then it's likely to be similar?

And if it *is* 27.0, can anyone recommend one? I've looked on eBay but branded ones in that size seem to be pretty thin on the ground. Is it worth holding out until I can find a Cinelli or 3TTT or Campag seatpost, or would a generic modern one suffice? Is there much of a weight difference?

I've just checked Tony Oliver's book which says 531ST is 27.0 for brass brazed, 27.2 for a silver brazed frame done to the highest standards. The difference is ovalization distortion from heating.

For a really nice 27.0 post, try looking for a Thomson.

Re:

Cheers - so it's probably likely to brass brazed, would you say? It's a decent frame by Raleigh standards but I'd imagine it's not likely to be anything particularly fancy.

Correct. A good quality, volume manufactured frame.
Generally the only stuff siver brazed was 753 (which had to be to avoid destroying the heat treatment).

How about sanding down a scratched 27.2 by a tenth of a millimeter? A two birds, one stone sort of solution.

Thanks for the solutions guys. I'll hold out for a 27.0 seatpost in the first instance.

I don't suppose anyone happens to know what size headset i'd need for the sand frame? I'd have thought it's be standard English dimensions but I've also read that Raleigh had their own dimensions at one point.

Headset will be standard 1" English thread, way back before your Frame was made Raleigh had their own threadings but had succumbed to ISO by then LOL

Shaun