531 ST Dawes Galaxy: what diameter...

...seatpost? It looks like 26 and a bit mm, but (having misplaced every actual measuring device in the house) I thought I'd better check! The seatpost is missing so i need to get hold of a new one (or develop very strong thighs )

Cheers,

Luke

would guess at 26.4 - this was the size for plain gauge 531

Thanks very much- I'll take a punt on that!

I think it's unlikely to be a plain gauge seat tube on an ST tube set. My last Galaxy was 27.0mm, and I have a feeling my older Super Galaxy was 26.8mm

531ST was sold in different gauges. The only way to be sure is to measure your frame, or try a number of posts until you find the right one.

I can't check as I have leant my copy of Tony Oliver's book to a mate but I think he lists sizes there. i know that many 531's take a 27.2 but should really be reamed to 27.4 as thats the true size. try and find the book maybe? or search for Reynolds tubing on the web.

Bugger! What kind of sadist takes out a seat post anyway? Jim, do you know what ages your Galaxy and Super Glaxy were?

Cheers,

Luke

Goldie":axci9oxq said:

Jim, do you know what ages your Galaxy and Super Glaxy were?

Click to expand...

The Super Galaxy was a 1990 model - Post Office red with full LX. The Galaxy had been resprayed, but was mid nineties. I also built a late eighties Galaxy for a friend about ten years ago, and remember very clearly the 27.0mm Ritchey seatpost that went in snugly.

Have a look at this chart:

http://www.equusbicycle.com/bike/reynol ... -sizes.jpg

The standard 531ST set has a 0.2mm thicker seat-tube wall than 531c. That implies a 0.4mm smaller seatpost than a typical 531c frame. But again, there's often more variety to be found in real bikes than in the catalogues (or in the selection of catalogues that have found their way onto the web), and the only way to be sure is to measure, or try a few different posts. Your local bike shop might have a sizing gauge if you can't lay your hands on a Vernier caliper.

My 97 galaxy was a loose fit at 27.0 so I reamed it out to a snug 27.2. Try 27.0 first