Seat set back, why

[john903]

Well on today's ride I put my Brooks B17 on my Hampsten, I switch out seats for those long summer rides as opposed to my turbomatic 3. So my question is why are setback seat post needed? My brooks I can only push back so far so i need a set back post. Why 20 or 30 years ago we never heard of a setback seat post, maybe changed the stem is all. Has bike geometry changed that much? My Hampsten is pretty basic 57X57 73deg angles non sloping top tube. My 82 Torpado was 55x55 74deg fast crit bike I used a 120 stem and a old Concor on a record post. Just something I was thinking about and was wondering if anyone else was wondering as well.
Thanks

[false_Aest]

Tilapia has been engineered to live in the Salton Sea.
http://en.wikipedia.org/wiki/Tilapia

Tomatoes are engineered to have tobacco qualities.
http://en.wikipedia.org/wiki/Products_produced_from_The_Simpsons#Tomacco

Mice can hear with their backs.
http://declubz.com/blog/wp-content/uploads/2008/08/mouse-human-ear.jpg

I suspect people have kids just to make their femurs longer.
:beer:

[1centaur]

20-30 years ago is only 1990 to 1980. Set backs have been around a while.

http://imagecache6.allposters.com/LRG/7/799/NUKI000Z.jpg

Using glute muscles and having the rails in the middle of the clamp rather than slammed back would be two reasons. Sometimes I hear that pros have longer femurs than average.

[bobswire]

Maybe cause folks buy frames that are not sized correctly ?

http://velo-orange.blogspot.com/2010/06/that-frame-doesnt-fit.html

[oldpotatoe]

Well on today's ride I put my Brooks B17 on my Hampsten, I switch out seats for those long summer rides as opposed to my turbomatic 3. So my question is why are setback seat post needed? My brooks I can only push back so far so i need a set back post. Why 20 or 30 years ago we never heard of a setback seat post, maybe changed the stem is all. Has bike geometry changed that much? My Hampsten is pretty basic 57X57 73deg angles non sloping top tube. My 82 Torpado was 55x55 74deg fast crit bike I used a 120 stem and a old Concor on a record post. Just something I was thinking about and was wondering if anyone else was wondering as well.
Thanks

Seatback or no setback seatposts because frame seat tube angles vary as does rider's femur lengths...to get the small 'c' constant of KOPS..Knee Over Pedal Spindle.

30 years ago was 1980...Campagnolo and others had been making setback seatposts since 1960, catalog number 14.

[rugbysecondrow]

Maybe cause folks buy frames that are not sized correctly ?

http://velo-orange.blogspot.com/2010/06/that-frame-doesnt-fit.html

Seems like a lot of conclusion with no path on how they got there. Seems out of whack to state a conclusion in a fashion that will make an explaination of "simplified frame fit guidelines" pretty conveneint. This also seems to fit well with a push for their line of bikes.