Since it’s snowing again, I’d like to set up my new (to me) tri-bike. My question is simply: should the seat height (seat to crank) be the same on my road bike (which fits very well) as it is on my tri-bike regardless of seat tube angle?
This seems to be the simplest way of determining seat position, because it lets me disregard all the other variables between the bikes (seat tube angle, 650 vs 700, saddle type, etc). Can I assume that since I’m rotating around the bottom bracket, that the leg position should stay the same? Should the measurement translate right over, keeping the same knee angle? Once I get the leg position set, then I can start playing with stems and drop and things like that.
I can’t speak for anyone else, but both my road and tri bikes have the same seat height.
Make sure to check your crank arm lengths and adjust accordingly. But they are pretty close otherwise.
Looks like it’s bike fitting day 
I thought most people raised the seat as the seat angle became steeper…I aslo thought this was covered in Dan’s fit pages.
Dave
I thought most people raised the seat as the seat angle became steeper…I aslo thought this was covered in Dan’s fit pages.
Dave
The seat is raised as the angle becomes steeper in order to maintain the same effective seat height, since, as the seat goes forward it becomes closer to the BB.
I am no expert but I would think you might want to raise it a little depending how large of an angle change you make. I think the important factor would be your knee angle.