Jamesh wrote:Just out of interest do the seat tube mesurements equate to a larger horizontal tope tube equivalent???
So a 53 might be a 55cm /22"
Seat tube C-T length minus 40mm = seat tube C-C
If you add 'top tube drop'/Sin(seat angle) to the seat tube C-C length then you will get the seat tube C-C length horizontal equivalent.
so for the 19" size
Seat tube C-C is 442.6mm
1/sin(74) = 1.04
TT drop is 55.01mm, x1.04 = 57.22 = seat tube correction
to be added to C-C measurement 442.6 + 57.22 ~ 500mm
so equivalent to a ~50cm C-C frame, (or 54cm C-T ) with horizontal top tube.
Simply because the head tube is ~34mm longer (C-C) in size 'L' so is the equivalent horizontal top tube size, so about 53.5cm (C-C) or 57.5cm (C-T).
Depending on whether you consider the seat tube and head tube protrusions as being structurally redundant or not, and depending how you like your ETT length (which differs by ~15mm on paper but effectively less than this because of the difference in seat angle), you could choose either M or L size if you would normally take a 22" C-T frame. As it happens this is about my size and since I prefer a 73deg seat angle, I don't need the bars super-low and the ETT measurements are not too long, a 'L' size frame is a better fit for me than 'M'.