Where they measured from? Is it the seat tube length? Thanks in advance.

top tube length

Cheers Samuri is that centre to centre?

yep

Samurai’s yanking your chain – the most important measure for fit on a road bike is top tube length.

However, the frames are sized on seat tube measurements. These vary (c2c, c2t, etc) as much as MTBs. There is no substitute for tring.

Well I have two, one 60cm(23 1/2″ actually) and the other 55.5cm (compact)and they both fit me. Varies so wildly between manufacturer you need to at least swing your leg over a half dozen to see what suits. Try to get a couple of test rides unless you’ve dropped on an unmissable bargain(the sort where you could sell on at a profit if it doesn’t suit).

Samurai’s yanking your chain – the most important measure for fit on a road bike is top tube length.

Pardon?

The original question was “Where they measured from?” and I’ve answered that correctly. Any road bike frame sizing given in a shop will be the top tube measurement. I agree though, there is no substitute for trying.