themidge wrote: ↑Mon Apr 02, 2018 4:36 pm
The numbers used to size frames (52, 54, 56, etc.) come from the length of the seat tube (and top tube as well, sometimes), so a frame with an
effective seat tube length of
about 54cm has a size of
about 54.
In the old days, when everything had straight top tubes and quill stems, yeah. Bikes are very different now, and ether real or effective seattube lengths are about the vaguest, least applicable to actual riding position measurements on the whole bike.
How else does one size a bike using those numbers?
How do you think Btwin decided your bike was a 52? Look at the geomerty charts and see if you can find out
(Actually, that's a bit unfair, the only Btwin geo charts I could see are very low on detail. Maybe look at some other geo charts, the Spesh ones are a lot better as are most big bike companies.)
I brought up the Allez Sprint because that is definitely what you would call a racing bike, and the 52 in that bike is way too low for me. I could get the same 'racing' position I have currently on my 'endurance' bike on a 54 or even 56 Allez Sprint (with varying degrees of slammage).
What length stem do you have on your Btwin? The ETT of the Allez 56 is 25mm longer than your 52. Do you think that means it's genuinely a comparably sized bike?
jekyll man wrote:and wingguy will always make sure he has the last word
........