Originally Posted by
Road Fan
Different opinions - I think it's for your balance on the bike - for me a sign of good balance is relaxed arms, low weight on the hands, and easy ability to raise up off the saddle. After that, adjust the reach with stem or bar reach adjustments.
I have to agree with noglider here. I see the BB-seat relationship as near sacred. Once I have that right, I can then rotate that relationship around the BB, to either seat back, a little lower and the seat more level or seat forward, up and a little more nose down. I have a CAD drafting program, so I just rotate the seat (and handlebars and levers) in the drawing. Many of my bikes I prefer more forward with real weight on my hands. A true blessing if I have to go 20 miles upwind, especially on the fix gears.
If I am starting from scratch, I put the bars where I can reach them, get the seat to the best first guess I can make and ride with all the seat adjust wrenches. Dial that in. Then I mess with dialing in the bars. Now, once I have the seat and bars dialed in, I can move the bars and rotate the seat position accordingly to change my aerodynamics and weight balance. But I have a lot of work I need to do first. (My theory on HB position ties in here also, but that is another thread.)
Ben