I've got an old Dawes road bike and like the frame so am upgrading all components to make things a bit lighter. The frame is Reynolds 500 tubing and I'm a bit stuck with the seatpost. As far as I can work out it is 25mm in diameter, but all the new ones that I see for sale are 27.2mm and upwards.

Have I measured the diameter incorrectly or can I still get one from somewhere that is lighter than the current cro-moly one that's in there.

Thanks,

Adrian

Adrian , have you taken your existing seatpost out and inspected it ? It could well have the sizing on it . Might I ask how you have measured it ?

Can't see any sizing on it at all.

Not having any calipers or micrometer, the best I could do was draw round the base of the seat post, allowing for the bevel at the bottom, then measure the diameter of the circle I'd drawn.

I'd better add that I haven't taken it to my LBS yet so perhaps that might be my best option.

If you can, use a vernier guage to measure the old post; it's probably 25.4 mm, but there were some old Raleigh seat posts that measure 25.8mm. You can still get forged alloy seat posts in those dimensions (RJ Chicken & sons) but I'm not so sure if you'll get the recent branded names.

Thanks for the info guys.

Managed to get to my LBS at lunch and they've sorted me out with one that's half the weight of the original one.

Cheers,